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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>9.16. JSON Functions and Operators</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="functions-xml.html" title="9.15. XML Functions" /><link rel="next" href="functions-sequence.html" title="9.17. Sequence Manipulation Functions" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">9.16. JSON Functions and Operators</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="functions-xml.html" title="9.15. XML Functions">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="functions.html" title="Chapter 9. Functions and Operators">Up</a></td><th width="60%" align="center">Chapter 9. Functions and Operators</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="functions-sequence.html" title="9.17. Sequence Manipulation Functions">Next</a></td></tr></table><hr /></div><div class="sect1" id="FUNCTIONS-JSON"><div class="titlepage"><div><div><h2 class="title" style="clear: both">9.16. JSON Functions and Operators <a href="#FUNCTIONS-JSON" class="id_link">#</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="sect2"><a href="functions-json.html#FUNCTIONS-JSON-PROCESSING">9.16.1. Processing and Creating JSON Data</a></span></dt><dt><span class="sect2"><a href="functions-json.html#FUNCTIONS-SQLJSON-PATH">9.16.2. The SQL/JSON Path Language</a></span></dt></dl></div><a id="id-1.5.8.22.2" class="indexterm"></a><a id="id-1.5.8.22.3" class="indexterm"></a><p>
This section describes:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
functions and operators for processing and creating JSON data
</p></li><li class="listitem"><p>
the SQL/JSON path language
</p></li></ul></div><p>
</p><p>
To provide native support for JSON data types within the SQL environment,
<span class="productname">PostgreSQL</span> implements the
<em class="firstterm">SQL/JSON data model</em>.
This model comprises sequences of items. Each item can hold SQL scalar
values, with an additional SQL/JSON null value, and composite data structures
that use JSON arrays and objects. The model is a formalization of the implied
data model in the JSON specification
<a class="ulink" href="https://datatracker.ietf.org/doc/html/rfc7159" target="_top">RFC 7159</a>.
</p><p>
SQL/JSON allows you to handle JSON data alongside regular SQL data,
with transaction support, including:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
Uploading JSON data into the database and storing it in
regular SQL columns as character or binary strings.
</p></li><li class="listitem"><p>
Generating JSON objects and arrays from relational data.
</p></li><li class="listitem"><p>
Querying JSON data using SQL/JSON query functions and
SQL/JSON path language expressions.
</p></li></ul></div><p>
</p><p>
To learn more about the SQL/JSON standard, see
<a class="xref" href="biblio.html#SQLTR-19075-6" title="SQL Technical Report">[sqltr-19075-6]</a>. For details on JSON types
supported in <span class="productname">PostgreSQL</span>,
see <a class="xref" href="datatype-json.html" title="8.14. JSON Types">Section 8.14</a>.
</p><div class="sect2" id="FUNCTIONS-JSON-PROCESSING"><div class="titlepage"><div><div><h3 class="title">9.16.1. Processing and Creating JSON Data <a href="#FUNCTIONS-JSON-PROCESSING" class="id_link">#</a></h3></div></div></div><p>
<a class="xref" href="functions-json.html#FUNCTIONS-JSON-OP-TABLE" title="Table 9.45. json and jsonb Operators">Table 9.45</a> shows the operators that
are available for use with JSON data types (see <a class="xref" href="datatype-json.html" title="8.14. JSON Types">Section 8.14</a>).
In addition, the usual comparison operators shown in <a class="xref" href="functions-comparison.html#FUNCTIONS-COMPARISON-OP-TABLE" title="Table 9.1. Comparison Operators">Table 9.1</a> are available for
<code class="type">jsonb</code>, though not for <code class="type">json</code>. The comparison
operators follow the ordering rules for B-tree operations outlined in
<a class="xref" href="datatype-json.html#JSON-INDEXING" title="8.14.4. jsonb Indexing">Section 8.14.4</a>.
See also <a class="xref" href="functions-aggregate.html" title="9.21. Aggregate Functions">Section 9.21</a> for the aggregate
function <code class="function">json_agg</code> which aggregates record
values as JSON, the aggregate function
<code class="function">json_object_agg</code> which aggregates pairs of values
into a JSON object, and their <code class="type">jsonb</code> equivalents,
<code class="function">jsonb_agg</code> and <code class="function">jsonb_object_agg</code>.
</p><div class="table" id="FUNCTIONS-JSON-OP-TABLE"><p class="title"><strong>Table 9.45. <code class="type">json</code> and <code class="type">jsonb</code> Operators</strong></p><div class="table-contents"><table class="table" summary="json and jsonb Operators" border="1"><colgroup><col /></colgroup><thead><tr><th class="func_table_entry"><p class="func_signature">
Operator
</p>
<p>
Description
</p>
<p>
Example(s)
</p></th></tr></thead><tbody><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">json</code> <code class="literal">-></code> <code class="type">integer</code>
→ <code class="returnvalue">json</code>
</p>
<p class="func_signature">
<code class="type">jsonb</code> <code class="literal">-></code> <code class="type">integer</code>
→ <code class="returnvalue">jsonb</code>
</p>
<p>
Extracts <em class="parameter"><code>n</code></em>'th element of JSON array
(array elements are indexed from zero, but negative integers count
from the end).
</p>
<p>
<code class="literal">'[{"a":"foo"},{"b":"bar"},{"c":"baz"}]'::json -> 2</code>
→ <code class="returnvalue">{"c":"baz"}</code>
</p>
<p>
<code class="literal">'[{"a":"foo"},{"b":"bar"},{"c":"baz"}]'::json -> -3</code>
→ <code class="returnvalue">{"a":"foo"}</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">json</code> <code class="literal">-></code> <code class="type">text</code>
→ <code class="returnvalue">json</code>
</p>
<p class="func_signature">
<code class="type">jsonb</code> <code class="literal">-></code> <code class="type">text</code>
→ <code class="returnvalue">jsonb</code>
</p>
<p>
Extracts JSON object field with the given key.
</p>
<p>
<code class="literal">'{"a": {"b":"foo"}}'::json -> 'a'</code>
→ <code class="returnvalue">{"b":"foo"}</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">json</code> <code class="literal">->></code> <code class="type">integer</code>
→ <code class="returnvalue">text</code>
</p>
<p class="func_signature">
<code class="type">jsonb</code> <code class="literal">->></code> <code class="type">integer</code>
→ <code class="returnvalue">text</code>
</p>
<p>
Extracts <em class="parameter"><code>n</code></em>'th element of JSON array,
as <code class="type">text</code>.
</p>
<p>
<code class="literal">'[1,2,3]'::json ->> 2</code>
→ <code class="returnvalue">3</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">json</code> <code class="literal">->></code> <code class="type">text</code>
→ <code class="returnvalue">text</code>
</p>
<p class="func_signature">
<code class="type">jsonb</code> <code class="literal">->></code> <code class="type">text</code>
→ <code class="returnvalue">text</code>
</p>
<p>
Extracts JSON object field with the given key, as <code class="type">text</code>.
</p>
<p>
<code class="literal">'{"a":1,"b":2}'::json ->> 'b'</code>
→ <code class="returnvalue">2</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">json</code> <code class="literal">#></code> <code class="type">text[]</code>
→ <code class="returnvalue">json</code>
</p>
<p class="func_signature">
<code class="type">jsonb</code> <code class="literal">#></code> <code class="type">text[]</code>
→ <code class="returnvalue">jsonb</code>
</p>
<p>
Extracts JSON sub-object at the specified path, where path elements
can be either field keys or array indexes.
</p>
<p>
<code class="literal">'{"a": {"b": ["foo","bar"]}}'::json #> '{a,b,1}'</code>
→ <code class="returnvalue">"bar"</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">json</code> <code class="literal">#>></code> <code class="type">text[]</code>
→ <code class="returnvalue">text</code>
</p>
<p class="func_signature">
<code class="type">jsonb</code> <code class="literal">#>></code> <code class="type">text[]</code>
→ <code class="returnvalue">text</code>
</p>
<p>
Extracts JSON sub-object at the specified path as <code class="type">text</code>.
</p>
<p>
<code class="literal">'{"a": {"b": ["foo","bar"]}}'::json #>> '{a,b,1}'</code>
→ <code class="returnvalue">bar</code>
</p></td></tr></tbody></table></div></div><br class="table-break" /><div class="note"><h3 class="title">Note</h3><p>
The field/element/path extraction operators return NULL, rather than
failing, if the JSON input does not have the right structure to match
the request; for example if no such key or array element exists.
</p></div><p>
Some further operators exist only for <code class="type">jsonb</code>, as shown
in <a class="xref" href="functions-json.html#FUNCTIONS-JSONB-OP-TABLE" title="Table 9.46. Additional jsonb Operators">Table 9.46</a>.
<a class="xref" href="datatype-json.html#JSON-INDEXING" title="8.14.4. jsonb Indexing">Section 8.14.4</a>
describes how these operators can be used to effectively search indexed
<code class="type">jsonb</code> data.
</p><div class="table" id="FUNCTIONS-JSONB-OP-TABLE"><p class="title"><strong>Table 9.46. Additional <code class="type">jsonb</code> Operators</strong></p><div class="table-contents"><table class="table" summary="Additional jsonb Operators" border="1"><colgroup><col /></colgroup><thead><tr><th class="func_table_entry"><p class="func_signature">
Operator
</p>
<p>
Description
</p>
<p>
Example(s)
</p></th></tr></thead><tbody><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">jsonb</code> <code class="literal">@></code> <code class="type">jsonb</code>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Does the first JSON value contain the second?
(See <a class="xref" href="datatype-json.html#JSON-CONTAINMENT" title="8.14.3. jsonb Containment and Existence">Section 8.14.3</a> for details about containment.)
</p>
<p>
<code class="literal">'{"a":1, "b":2}'::jsonb @> '{"b":2}'::jsonb</code>
→ <code class="returnvalue">t</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">jsonb</code> <code class="literal"><@</code> <code class="type">jsonb</code>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Is the first JSON value contained in the second?
</p>
<p>
<code class="literal">'{"b":2}'::jsonb <@ '{"a":1, "b":2}'::jsonb</code>
→ <code class="returnvalue">t</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">jsonb</code> <code class="literal">?</code> <code class="type">text</code>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Does the text string exist as a top-level key or array element within
the JSON value?
</p>
<p>
<code class="literal">'{"a":1, "b":2}'::jsonb ? 'b'</code>
→ <code class="returnvalue">t</code>
</p>
<p>
<code class="literal">'["a", "b", "c"]'::jsonb ? 'b'</code>
→ <code class="returnvalue">t</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">jsonb</code> <code class="literal">?|</code> <code class="type">text[]</code>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Do any of the strings in the text array exist as top-level keys or
array elements?
</p>
<p>
<code class="literal">'{"a":1, "b":2, "c":3}'::jsonb ?| array['b', 'd']</code>
→ <code class="returnvalue">t</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">jsonb</code> <code class="literal">?&</code> <code class="type">text[]</code>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Do all of the strings in the text array exist as top-level keys or
array elements?
</p>
<p>
<code class="literal">'["a", "b", "c"]'::jsonb ?& array['a', 'b']</code>
→ <code class="returnvalue">t</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">jsonb</code> <code class="literal">||</code> <code class="type">jsonb</code>
→ <code class="returnvalue">jsonb</code>
</p>
<p>
Concatenates two <code class="type">jsonb</code> values.
Concatenating two arrays generates an array containing all the
elements of each input. Concatenating two objects generates an
object containing the union of their
keys, taking the second object's value when there are duplicate keys.
All other cases are treated by converting a non-array input into a
single-element array, and then proceeding as for two arrays.
Does not operate recursively: only the top-level array or object
structure is merged.
</p>
<p>
<code class="literal">'["a", "b"]'::jsonb || '["a", "d"]'::jsonb</code>
→ <code class="returnvalue">["a", "b", "a", "d"]</code>
</p>
<p>
<code class="literal">'{"a": "b"}'::jsonb || '{"c": "d"}'::jsonb</code>
→ <code class="returnvalue">{"a": "b", "c": "d"}</code>
</p>
<p>
<code class="literal">'[1, 2]'::jsonb || '3'::jsonb</code>
→ <code class="returnvalue">[1, 2, 3]</code>
</p>
<p>
<code class="literal">'{"a": "b"}'::jsonb || '42'::jsonb</code>
→ <code class="returnvalue">[{"a": "b"}, 42]</code>
</p>
<p>
To append an array to another array as a single entry, wrap it
in an additional layer of array, for example:
</p>
<p>
<code class="literal">'[1, 2]'::jsonb || jsonb_build_array('[3, 4]'::jsonb)</code>
→ <code class="returnvalue">[1, 2, [3, 4]]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">jsonb</code> <code class="literal">-</code> <code class="type">text</code>
→ <code class="returnvalue">jsonb</code>
</p>
<p>
Deletes a key (and its value) from a JSON object, or matching string
value(s) from a JSON array.
</p>
<p>
<code class="literal">'{"a": "b", "c": "d"}'::jsonb - 'a'</code>
→ <code class="returnvalue">{"c": "d"}</code>
</p>
<p>
<code class="literal">'["a", "b", "c", "b"]'::jsonb - 'b'</code>
→ <code class="returnvalue">["a", "c"]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">jsonb</code> <code class="literal">-</code> <code class="type">text[]</code>
→ <code class="returnvalue">jsonb</code>
</p>
<p>
Deletes all matching keys or array elements from the left operand.
</p>
<p>
<code class="literal">'{"a": "b", "c": "d"}'::jsonb - '{a,c}'::text[]</code>
→ <code class="returnvalue">{}</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">jsonb</code> <code class="literal">-</code> <code class="type">integer</code>
→ <code class="returnvalue">jsonb</code>
</p>
<p>
Deletes the array element with specified index (negative
integers count from the end). Throws an error if JSON value
is not an array.
</p>
<p>
<code class="literal">'["a", "b"]'::jsonb - 1 </code>
→ <code class="returnvalue">["a"]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">jsonb</code> <code class="literal">#-</code> <code class="type">text[]</code>
→ <code class="returnvalue">jsonb</code>
</p>
<p>
Deletes the field or array element at the specified path, where path
elements can be either field keys or array indexes.
</p>
<p>
<code class="literal">'["a", {"b":1}]'::jsonb #- '{1,b}'</code>
→ <code class="returnvalue">["a", {}]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">jsonb</code> <code class="literal">@?</code> <code class="type">jsonpath</code>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Does JSON path return any item for the specified JSON value?
</p>
<p>
<code class="literal">'{"a":[1,2,3,4,5]}'::jsonb @? '$.a[*] ? (@ > 2)'</code>
→ <code class="returnvalue">t</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">jsonb</code> <code class="literal">@@</code> <code class="type">jsonpath</code>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Returns the result of a JSON path predicate check for the
specified JSON value. Only the first item of the result is taken into
account. If the result is not Boolean, then <code class="literal">NULL</code>
is returned.
</p>
<p>
<code class="literal">'{"a":[1,2,3,4,5]}'::jsonb @@ '$.a[*] > 2'</code>
→ <code class="returnvalue">t</code>
</p></td></tr></tbody></table></div></div><br class="table-break" /><div class="note"><h3 class="title">Note</h3><p>
The <code class="type">jsonpath</code> operators <code class="literal">@?</code>
and <code class="literal">@@</code> suppress the following errors: missing object
field or array element, unexpected JSON item type, datetime and numeric
errors. The <code class="type">jsonpath</code>-related functions described below can
also be told to suppress these types of errors. This behavior might be
helpful when searching JSON document collections of varying structure.
</p></div><p>
<a class="xref" href="functions-json.html#FUNCTIONS-JSON-CREATION-TABLE" title="Table 9.47. JSON Creation Functions">Table 9.47</a> shows the functions that are
available for constructing <code class="type">json</code> and <code class="type">jsonb</code> values.
Some functions in this table have a <code class="literal">RETURNING</code> clause,
which specifies the data type returned. It must be one of <code class="type">json</code>,
<code class="type">jsonb</code>, <code class="type">bytea</code>, a character string type (<code class="type">text</code>,
<code class="type">char</code>, or <code class="type">varchar</code>), or a type
for which there is a cast from <code class="type">json</code> to that type.
By default, the <code class="type">json</code> type is returned.
</p><div class="table" id="FUNCTIONS-JSON-CREATION-TABLE"><p class="title"><strong>Table 9.47. JSON Creation Functions</strong></p><div class="table-contents"><table class="table" summary="JSON Creation Functions" border="1"><colgroup><col /></colgroup><thead><tr><th class="func_table_entry"><p class="func_signature">
Function
</p>
<p>
Description
</p>
<p>
Example(s)
</p></th></tr></thead><tbody><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.9.2.2.1.1.1.1" class="indexterm"></a>
<code class="function">to_json</code> ( <code class="type">anyelement</code> )
→ <code class="returnvalue">json</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.9.2.2.1.1.2.1" class="indexterm"></a>
<code class="function">to_jsonb</code> ( <code class="type">anyelement</code> )
→ <code class="returnvalue">jsonb</code>
</p>
<p>
Converts any SQL value to <code class="type">json</code> or <code class="type">jsonb</code>.
Arrays and composites are converted recursively to arrays and
objects (multidimensional arrays become arrays of arrays in JSON).
Otherwise, if there is a cast from the SQL data type
to <code class="type">json</code>, the cast function will be used to perform the
conversion;<a href="#ftn.id-1.5.8.22.8.9.2.2.1.1.3.4" class="footnote"><sup class="footnote" id="id-1.5.8.22.8.9.2.2.1.1.3.4">[a]</sup></a>
otherwise, a scalar JSON value is produced. For any scalar other than
a number, a Boolean, or a null value, the text representation will be
used, with escaping as necessary to make it a valid JSON string value.
</p>
<p>
<code class="literal">to_json('Fred said "Hi."'::text)</code>
→ <code class="returnvalue">"Fred said \"Hi.\""</code>
</p>
<p>
<code class="literal">to_jsonb(row(42, 'Fred said "Hi."'::text))</code>
→ <code class="returnvalue">{"f1": 42, "f2": "Fred said \"Hi.\""}</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.9.2.2.2.1.1.1" class="indexterm"></a>
<code class="function">array_to_json</code> ( <code class="type">anyarray</code> [<span class="optional">, <code class="type">boolean</code> </span>] )
→ <code class="returnvalue">json</code>
</p>
<p>
Converts an SQL array to a JSON array. The behavior is the same
as <code class="function">to_json</code> except that line feeds will be added
between top-level array elements if the optional boolean parameter is
true.
</p>
<p>
<code class="literal">array_to_json('{{1,5},{99,100}}'::int[])</code>
→ <code class="returnvalue">[[1,5],[99,100]]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.9.2.2.3.1.1.1" class="indexterm"></a>
<code class="function">json_array</code> (
[<span class="optional"> { <em class="replaceable"><code>value_expression</code></em> [<span class="optional"> <code class="literal">FORMAT JSON</code> </span>] } [<span class="optional">, ...</span>] </span>]
[<span class="optional"> { <code class="literal">NULL</code> | <code class="literal">ABSENT</code> } <code class="literal">ON NULL</code> </span>]
[<span class="optional"> <code class="literal">RETURNING</code> <em class="replaceable"><code>data_type</code></em> [<span class="optional"> <code class="literal">FORMAT JSON</code> [<span class="optional"> <code class="literal">ENCODING UTF8</code> </span>] </span>] </span>])
</p>
<p class="func_signature">
<code class="function">json_array</code> (
[<span class="optional"> <em class="replaceable"><code>query_expression</code></em> </span>]
[<span class="optional"> <code class="literal">RETURNING</code> <em class="replaceable"><code>data_type</code></em> [<span class="optional"> <code class="literal">FORMAT JSON</code> [<span class="optional"> <code class="literal">ENCODING UTF8</code> </span>] </span>] </span>])
</p>
<p>
Constructs a JSON array from either a series of
<em class="replaceable"><code>value_expression</code></em> parameters or from the results
of <em class="replaceable"><code>query_expression</code></em>,
which must be a SELECT query returning a single column. If
<code class="literal">ABSENT ON NULL</code> is specified, NULL values are ignored.
This is always the case if a
<em class="replaceable"><code>query_expression</code></em> is used.
</p>
<p>
<code class="literal">json_array(1,true,json '{"a":null}')</code>
→ <code class="returnvalue">[1, true, {"a":null}]</code>
</p>
<p>
<code class="literal">json_array(SELECT * FROM (VALUES(1),(2)) t)</code>
→ <code class="returnvalue">[1, 2]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.9.2.2.4.1.1.1" class="indexterm"></a>
<code class="function">row_to_json</code> ( <code class="type">record</code> [<span class="optional">, <code class="type">boolean</code> </span>] )
→ <code class="returnvalue">json</code>
</p>
<p>
Converts an SQL composite value to a JSON object. The behavior is the
same as <code class="function">to_json</code> except that line feeds will be
added between top-level elements if the optional boolean parameter is
true.
</p>
<p>
<code class="literal">row_to_json(row(1,'foo'))</code>
→ <code class="returnvalue">{"f1":1,"f2":"foo"}</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.9.2.2.5.1.1.1" class="indexterm"></a>
<code class="function">json_build_array</code> ( <code class="literal">VARIADIC</code> <code class="type">"any"</code> )
→ <code class="returnvalue">json</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.9.2.2.5.1.2.1" class="indexterm"></a>
<code class="function">jsonb_build_array</code> ( <code class="literal">VARIADIC</code> <code class="type">"any"</code> )
→ <code class="returnvalue">jsonb</code>
</p>
<p>
Builds a possibly-heterogeneously-typed JSON array out of a variadic
argument list. Each argument is converted as
per <code class="function">to_json</code> or <code class="function">to_jsonb</code>.
</p>
<p>
<code class="literal">json_build_array(1, 2, 'foo', 4, 5)</code>
→ <code class="returnvalue">[1, 2, "foo", 4, 5]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.9.2.2.6.1.1.1" class="indexterm"></a>
<code class="function">json_build_object</code> ( <code class="literal">VARIADIC</code> <code class="type">"any"</code> )
→ <code class="returnvalue">json</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.9.2.2.6.1.2.1" class="indexterm"></a>
<code class="function">jsonb_build_object</code> ( <code class="literal">VARIADIC</code> <code class="type">"any"</code> )
→ <code class="returnvalue">jsonb</code>
</p>
<p>
Builds a JSON object out of a variadic argument list. By convention,
the argument list consists of alternating keys and values. Key
arguments are coerced to text; value arguments are converted as
per <code class="function">to_json</code> or <code class="function">to_jsonb</code>.
</p>
<p>
<code class="literal">json_build_object('foo', 1, 2, row(3,'bar'))</code>
→ <code class="returnvalue">{"foo" : 1, "2" : {"f1":3,"f2":"bar"}}</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.9.2.2.7.1.1.1" class="indexterm"></a>
<code class="function">json_object</code> (
[<span class="optional"> { <em class="replaceable"><code>key_expression</code></em> { <code class="literal">VALUE</code> | ':' }
<em class="replaceable"><code>value_expression</code></em> [<span class="optional"> <code class="literal">FORMAT JSON</code> [<span class="optional"> <code class="literal">ENCODING UTF8</code> </span>] </span>] }[<span class="optional">, ...</span>] </span>]
[<span class="optional"> { <code class="literal">NULL</code> | <code class="literal">ABSENT</code> } <code class="literal">ON NULL</code> </span>]
[<span class="optional"> { <code class="literal">WITH</code> | <code class="literal">WITHOUT</code> } <code class="literal">UNIQUE</code> [<span class="optional"> <code class="literal">KEYS</code> </span>] </span>]
[<span class="optional"> <code class="literal">RETURNING</code> <em class="replaceable"><code>data_type</code></em> [<span class="optional"> <code class="literal">FORMAT JSON</code> [<span class="optional"> <code class="literal">ENCODING UTF8</code> </span>] </span>] </span>])
</p>
<p>
Constructs a JSON object of all the key/value pairs given,
or an empty object if none are given.
<em class="replaceable"><code>key_expression</code></em> is a scalar expression
defining the <acronym class="acronym">JSON</acronym> key, which is
converted to the <code class="type">text</code> type.
It cannot be <code class="literal">NULL</code> nor can it
belong to a type that has a cast to the <code class="type">json</code> type.
If <code class="literal">WITH UNIQUE KEYS</code> is specified, there must not
be any duplicate <em class="replaceable"><code>key_expression</code></em>.
Any pair for which the <em class="replaceable"><code>value_expression</code></em>
evaluates to <code class="literal">NULL</code> is omitted from the output
if <code class="literal">ABSENT ON NULL</code> is specified;
if <code class="literal">NULL ON NULL</code> is specified or the clause
omitted, the key is included with value <code class="literal">NULL</code>.
</p>
<p>
<code class="literal">json_object('code' VALUE 'P123', 'title': 'Jaws')</code>
→ <code class="returnvalue">{"code" : "P123", "title" : "Jaws"}</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.9.2.2.8.1.1.1" class="indexterm"></a>
<code class="function">json_object</code> ( <code class="type">text[]</code> )
→ <code class="returnvalue">json</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.9.2.2.8.1.2.1" class="indexterm"></a>
<code class="function">jsonb_object</code> ( <code class="type">text[]</code> )
→ <code class="returnvalue">jsonb</code>
</p>
<p>
Builds a JSON object out of a text array. The array must have either
exactly one dimension with an even number of members, in which case
they are taken as alternating key/value pairs, or two dimensions
such that each inner array has exactly two elements, which
are taken as a key/value pair. All values are converted to JSON
strings.
</p>
<p>
<code class="literal">json_object('{a, 1, b, "def", c, 3.5}')</code>
→ <code class="returnvalue">{"a" : "1", "b" : "def", "c" : "3.5"}</code>
</p>
<p><code class="literal">json_object('{{a, 1}, {b, "def"}, {c, 3.5}}')</code>
→ <code class="returnvalue">{"a" : "1", "b" : "def", "c" : "3.5"}</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="function">json_object</code> ( <em class="parameter"><code>keys</code></em> <code class="type">text[]</code>, <em class="parameter"><code>values</code></em> <code class="type">text[]</code> )
→ <code class="returnvalue">json</code>
</p>
<p class="func_signature">
<code class="function">jsonb_object</code> ( <em class="parameter"><code>keys</code></em> <code class="type">text[]</code>, <em class="parameter"><code>values</code></em> <code class="type">text[]</code> )
→ <code class="returnvalue">jsonb</code>
</p>
<p>
This form of <code class="function">json_object</code> takes keys and values
pairwise from separate text arrays. Otherwise it is identical to
the one-argument form.
</p>
<p>
<code class="literal">json_object('{a,b}', '{1,2}')</code>
→ <code class="returnvalue">{"a": "1", "b": "2"}</code>
</p></td></tr></tbody><tbody class="footnotes"><tr><td colspan="1"><div id="ftn.id-1.5.8.22.8.9.2.2.1.1.3.4" class="footnote"><p><a href="#id-1.5.8.22.8.9.2.2.1.1.3.4" class="para"><sup class="para">[a] </sup></a>
For example, the <a class="xref" href="hstore.html" title="F.18. hstore — hstore key/value datatype">hstore</a> extension has a cast
from <code class="type">hstore</code> to <code class="type">json</code>, so that
<code class="type">hstore</code> values converted via the JSON creation functions
will be represented as JSON objects, not as primitive string values.
</p></div></td></tr></tbody></table></div></div><br class="table-break" /><p>
<a class="xref" href="functions-json.html#FUNCTIONS-SQLJSON-MISC" title="Table 9.48. SQL/JSON Testing Functions">Table 9.48</a> details SQL/JSON
facilities for testing JSON.
</p><div class="table" id="FUNCTIONS-SQLJSON-MISC"><p class="title"><strong>Table 9.48. SQL/JSON Testing Functions</strong></p><div class="table-contents"><table class="table" summary="SQL/JSON Testing Functions" border="1"><colgroup><col /></colgroup><thead><tr><th class="func_table_entry"><p class="func_signature">
Function signature
</p>
<p>
Description
</p>
<p>
Example(s)
</p></th></tr></thead><tbody><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.11.2.2.1.1.1.1" class="indexterm"></a>
<em class="replaceable"><code>expression</code></em> <code class="literal">IS</code> [<span class="optional"> <code class="literal">NOT</code> </span>] <code class="literal">JSON</code>
[<span class="optional"> { <code class="literal">VALUE</code> | <code class="literal">SCALAR</code> | <code class="literal">ARRAY</code> | <code class="literal">OBJECT</code> } </span>]
[<span class="optional"> { <code class="literal">WITH</code> | <code class="literal">WITHOUT</code> } <code class="literal">UNIQUE</code> [<span class="optional"> <code class="literal">KEYS</code> </span>] </span>]
</p>
<p>
This predicate tests whether <em class="replaceable"><code>expression</code></em> can be
parsed as JSON, possibly of a specified type.
If <code class="literal">SCALAR</code> or <code class="literal">ARRAY</code> or
<code class="literal">OBJECT</code> is specified, the
test is whether or not the JSON is of that particular type. If
<code class="literal">WITH UNIQUE KEYS</code> is specified, then any object in the
<em class="replaceable"><code>expression</code></em> is also tested to see if it
has duplicate keys.
</p>
<p>
</p><pre class="programlisting">
SELECT js,
js IS JSON "json?",
js IS JSON SCALAR "scalar?",
js IS JSON OBJECT "object?",
js IS JSON ARRAY "array?"
FROM (VALUES
('123'), ('"abc"'), ('{"a": "b"}'), ('[1,2]'),('abc')) foo(js);
js | json? | scalar? | object? | array?
------------+-------+---------+---------+--------
123 | t | t | f | f
"abc" | t | t | f | f
{"a": "b"} | t | f | t | f
[1,2] | t | f | f | t
abc | f | f | f | f
</pre><p>
</p>
<p>
</p><pre class="programlisting">
SELECT js,
js IS JSON OBJECT "object?",
js IS JSON ARRAY "array?",
js IS JSON ARRAY WITH UNIQUE KEYS "array w. UK?",
js IS JSON ARRAY WITHOUT UNIQUE KEYS "array w/o UK?"
FROM (VALUES ('[{"a":"1"},
{"b":"2","b":"3"}]')) foo(js);
-[ RECORD 1 ]-+--------------------
js | [{"a":"1"}, +
| {"b":"2","b":"3"}]
object? | f
array? | t
array w. UK? | f
array w/o UK? | t
</pre><p>
</p></td></tr></tbody></table></div></div><br class="table-break" /><p>
<a class="xref" href="functions-json.html#FUNCTIONS-JSON-PROCESSING-TABLE" title="Table 9.49. JSON Processing Functions">Table 9.49</a> shows the functions that
are available for processing <code class="type">json</code> and <code class="type">jsonb</code> values.
</p><div class="table" id="FUNCTIONS-JSON-PROCESSING-TABLE"><p class="title"><strong>Table 9.49. JSON Processing Functions</strong></p><div class="table-contents"><table class="table" summary="JSON Processing Functions" border="1"><colgroup><col /></colgroup><thead><tr><th class="func_table_entry"><p class="func_signature">
Function
</p>
<p>
Description
</p>
<p>
Example(s)
</p></th></tr></thead><tbody><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.1.1.1.1" class="indexterm"></a>
<code class="function">json_array_elements</code> ( <code class="type">json</code> )
→ <code class="returnvalue">setof json</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.1.1.2.1" class="indexterm"></a>
<code class="function">jsonb_array_elements</code> ( <code class="type">jsonb</code> )
→ <code class="returnvalue">setof jsonb</code>
</p>
<p>
Expands the top-level JSON array into a set of JSON values.
</p>
<p>
<code class="literal">select * from json_array_elements('[1,true, [2,false]]')</code>
→ <code class="returnvalue"></code>
</p><pre class="programlisting">
value
-----------
1
true
[2,false]
</pre><p>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.2.1.1.1" class="indexterm"></a>
<code class="function">json_array_elements_text</code> ( <code class="type">json</code> )
→ <code class="returnvalue">setof text</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.2.1.2.1" class="indexterm"></a>
<code class="function">jsonb_array_elements_text</code> ( <code class="type">jsonb</code> )
→ <code class="returnvalue">setof text</code>
</p>
<p>
Expands the top-level JSON array into a set of <code class="type">text</code> values.
</p>
<p>
<code class="literal">select * from json_array_elements_text('["foo", "bar"]')</code>
→ <code class="returnvalue"></code>
</p><pre class="programlisting">
value
-----------
foo
bar
</pre><p>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.3.1.1.1" class="indexterm"></a>
<code class="function">json_array_length</code> ( <code class="type">json</code> )
→ <code class="returnvalue">integer</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.3.1.2.1" class="indexterm"></a>
<code class="function">jsonb_array_length</code> ( <code class="type">jsonb</code> )
→ <code class="returnvalue">integer</code>
</p>
<p>
Returns the number of elements in the top-level JSON array.
</p>
<p>
<code class="literal">json_array_length('[1,2,3,{"f1":1,"f2":[5,6]},4]')</code>
→ <code class="returnvalue">5</code>
</p>
<p>
<code class="literal">jsonb_array_length('[]')</code>
→ <code class="returnvalue">0</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.4.1.1.1" class="indexterm"></a>
<code class="function">json_each</code> ( <code class="type">json</code> )
→ <code class="returnvalue">setof record</code>
( <em class="parameter"><code>key</code></em> <code class="type">text</code>,
<em class="parameter"><code>value</code></em> <code class="type">json</code> )
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.4.1.2.1" class="indexterm"></a>
<code class="function">jsonb_each</code> ( <code class="type">jsonb</code> )
→ <code class="returnvalue">setof record</code>
( <em class="parameter"><code>key</code></em> <code class="type">text</code>,
<em class="parameter"><code>value</code></em> <code class="type">jsonb</code> )
</p>
<p>
Expands the top-level JSON object into a set of key/value pairs.
</p>
<p>
<code class="literal">select * from json_each('{"a":"foo", "b":"bar"}')</code>
→ <code class="returnvalue"></code>
</p><pre class="programlisting">
key | value
-----+-------
a | "foo"
b | "bar"
</pre><p>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.5.1.1.1" class="indexterm"></a>
<code class="function">json_each_text</code> ( <code class="type">json</code> )
→ <code class="returnvalue">setof record</code>
( <em class="parameter"><code>key</code></em> <code class="type">text</code>,
<em class="parameter"><code>value</code></em> <code class="type">text</code> )
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.5.1.2.1" class="indexterm"></a>
<code class="function">jsonb_each_text</code> ( <code class="type">jsonb</code> )
→ <code class="returnvalue">setof record</code>
( <em class="parameter"><code>key</code></em> <code class="type">text</code>,
<em class="parameter"><code>value</code></em> <code class="type">text</code> )
</p>
<p>
Expands the top-level JSON object into a set of key/value pairs.
The returned <em class="parameter"><code>value</code></em>s will be of
type <code class="type">text</code>.
</p>
<p>
<code class="literal">select * from json_each_text('{"a":"foo", "b":"bar"}')</code>
→ <code class="returnvalue"></code>
</p><pre class="programlisting">
key | value
-----+-------
a | foo
b | bar
</pre><p>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.6.1.1.1" class="indexterm"></a>
<code class="function">json_extract_path</code> ( <em class="parameter"><code>from_json</code></em> <code class="type">json</code>, <code class="literal">VARIADIC</code> <em class="parameter"><code>path_elems</code></em> <code class="type">text[]</code> )
→ <code class="returnvalue">json</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.6.1.2.1" class="indexterm"></a>
<code class="function">jsonb_extract_path</code> ( <em class="parameter"><code>from_json</code></em> <code class="type">jsonb</code>, <code class="literal">VARIADIC</code> <em class="parameter"><code>path_elems</code></em> <code class="type">text[]</code> )
→ <code class="returnvalue">jsonb</code>
</p>
<p>
Extracts JSON sub-object at the specified path.
(This is functionally equivalent to the <code class="literal">#></code>
operator, but writing the path out as a variadic list can be more
convenient in some cases.)
</p>
<p>
<code class="literal">json_extract_path('{"f2":{"f3":1},"f4":{"f5":99,"f6":"foo"}}', 'f4', 'f6')</code>
→ <code class="returnvalue">"foo"</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.7.1.1.1" class="indexterm"></a>
<code class="function">json_extract_path_text</code> ( <em class="parameter"><code>from_json</code></em> <code class="type">json</code>, <code class="literal">VARIADIC</code> <em class="parameter"><code>path_elems</code></em> <code class="type">text[]</code> )
→ <code class="returnvalue">text</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.7.1.2.1" class="indexterm"></a>
<code class="function">jsonb_extract_path_text</code> ( <em class="parameter"><code>from_json</code></em> <code class="type">jsonb</code>, <code class="literal">VARIADIC</code> <em class="parameter"><code>path_elems</code></em> <code class="type">text[]</code> )
→ <code class="returnvalue">text</code>
</p>
<p>
Extracts JSON sub-object at the specified path as <code class="type">text</code>.
(This is functionally equivalent to the <code class="literal">#>></code>
operator.)
</p>
<p>
<code class="literal">json_extract_path_text('{"f2":{"f3":1},"f4":{"f5":99,"f6":"foo"}}', 'f4', 'f6')</code>
→ <code class="returnvalue">foo</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.8.1.1.1" class="indexterm"></a>
<code class="function">json_object_keys</code> ( <code class="type">json</code> )
→ <code class="returnvalue">setof text</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.8.1.2.1" class="indexterm"></a>
<code class="function">jsonb_object_keys</code> ( <code class="type">jsonb</code> )
→ <code class="returnvalue">setof text</code>
</p>
<p>
Returns the set of keys in the top-level JSON object.
</p>
<p>
<code class="literal">select * from json_object_keys('{"f1":"abc","f2":{"f3":"a", "f4":"b"}}')</code>
→ <code class="returnvalue"></code>
</p><pre class="programlisting">
json_object_keys
------------------
f1
f2
</pre><p>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.9.1.1.1" class="indexterm"></a>
<code class="function">json_populate_record</code> ( <em class="parameter"><code>base</code></em> <code class="type">anyelement</code>, <em class="parameter"><code>from_json</code></em> <code class="type">json</code> )
→ <code class="returnvalue">anyelement</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.9.1.2.1" class="indexterm"></a>
<code class="function">jsonb_populate_record</code> ( <em class="parameter"><code>base</code></em> <code class="type">anyelement</code>, <em class="parameter"><code>from_json</code></em> <code class="type">jsonb</code> )
→ <code class="returnvalue">anyelement</code>
</p>
<p>
Expands the top-level JSON object to a row having the composite type
of the <em class="parameter"><code>base</code></em> argument. The JSON object
is scanned for fields whose names match column names of the output row
type, and their values are inserted into those columns of the output.
(Fields that do not correspond to any output column name are ignored.)
In typical use, the value of <em class="parameter"><code>base</code></em> is just
<code class="literal">NULL</code>, which means that any output columns that do
not match any object field will be filled with nulls. However,
if <em class="parameter"><code>base</code></em> isn't <code class="literal">NULL</code> then
the values it contains will be used for unmatched columns.
</p>
<p>
To convert a JSON value to the SQL type of an output column, the
following rules are applied in sequence:
</p><div class="itemizedlist"><ul class="itemizedlist compact" style="list-style-type: disc; "><li class="listitem"><p>
A JSON null value is converted to an SQL null in all cases.
</p></li><li class="listitem"><p>
If the output column is of type <code class="type">json</code>
or <code class="type">jsonb</code>, the JSON value is just reproduced exactly.
</p></li><li class="listitem"><p>
If the output column is a composite (row) type, and the JSON value
is a JSON object, the fields of the object are converted to columns
of the output row type by recursive application of these rules.
</p></li><li class="listitem"><p>
Likewise, if the output column is an array type and the JSON value
is a JSON array, the elements of the JSON array are converted to
elements of the output array by recursive application of these
rules.
</p></li><li class="listitem"><p>
Otherwise, if the JSON value is a string, the contents of the
string are fed to the input conversion function for the column's
data type.
</p></li><li class="listitem"><p>
Otherwise, the ordinary text representation of the JSON value is
fed to the input conversion function for the column's data type.
</p></li></ul></div><p>
</p>
<p>
While the example below uses a constant JSON value, typical use would
be to reference a <code class="type">json</code> or <code class="type">jsonb</code> column
laterally from another table in the query's <code class="literal">FROM</code>
clause. Writing <code class="function">json_populate_record</code> in
the <code class="literal">FROM</code> clause is good practice, since all of the
extracted columns are available for use without duplicate function
calls.
</p>
<p>
<code class="literal">create type subrowtype as (d int, e text);</code>
<code class="literal">create type myrowtype as (a int, b text[], c subrowtype);</code>
</p>
<p>
<code class="literal">select * from json_populate_record(null::myrowtype,
'{"a": 1, "b": ["2", "a b"], "c": {"d": 4, "e": "a b c"}, "x": "foo"}')</code>
→ <code class="returnvalue"></code>
</p><pre class="programlisting">
a | b | c
---+-----------+-------------
1 | {2,"a b"} | (4,"a b c")
</pre><p>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.10.1.1.1" class="indexterm"></a>
<code class="function">json_populate_recordset</code> ( <em class="parameter"><code>base</code></em> <code class="type">anyelement</code>, <em class="parameter"><code>from_json</code></em> <code class="type">json</code> )
→ <code class="returnvalue">setof anyelement</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.10.1.2.1" class="indexterm"></a>
<code class="function">jsonb_populate_recordset</code> ( <em class="parameter"><code>base</code></em> <code class="type">anyelement</code>, <em class="parameter"><code>from_json</code></em> <code class="type">jsonb</code> )
→ <code class="returnvalue">setof anyelement</code>
</p>
<p>
Expands the top-level JSON array of objects to a set of rows having
the composite type of the <em class="parameter"><code>base</code></em> argument.
Each element of the JSON array is processed as described above
for <code class="function">json[b]_populate_record</code>.
</p>
<p>
<code class="literal">create type twoints as (a int, b int);</code>
</p>
<p>
<code class="literal">select * from json_populate_recordset(null::twoints, '[{"a":1,"b":2}, {"a":3,"b":4}]')</code>
→ <code class="returnvalue"></code>
</p><pre class="programlisting">
a | b
---+---
1 | 2
3 | 4
</pre><p>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.11.1.1.1" class="indexterm"></a>
<code class="function">json_to_record</code> ( <code class="type">json</code> )
→ <code class="returnvalue">record</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.11.1.2.1" class="indexterm"></a>
<code class="function">jsonb_to_record</code> ( <code class="type">jsonb</code> )
→ <code class="returnvalue">record</code>
</p>
<p>
Expands the top-level JSON object to a row having the composite type
defined by an <code class="literal">AS</code> clause. (As with all functions
returning <code class="type">record</code>, the calling query must explicitly
define the structure of the record with an <code class="literal">AS</code>
clause.) The output record is filled from fields of the JSON object,
in the same way as described above
for <code class="function">json[b]_populate_record</code>. Since there is no
input record value, unmatched columns are always filled with nulls.
</p>
<p>
<code class="literal">create type myrowtype as (a int, b text);</code>
</p>
<p>
<code class="literal">select * from json_to_record('{"a":1,"b":[1,2,3],"c":[1,2,3],"e":"bar","r": {"a": 123, "b": "a b c"}}') as x(a int, b text, c int[], d text, r myrowtype)</code>
→ <code class="returnvalue"></code>
</p><pre class="programlisting">
a | b | c | d | r
---+---------+---------+---+---------------
1 | [1,2,3] | {1,2,3} | | (123,"a b c")
</pre><p>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.12.1.1.1" class="indexterm"></a>
<code class="function">json_to_recordset</code> ( <code class="type">json</code> )
→ <code class="returnvalue">setof record</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.12.1.2.1" class="indexterm"></a>
<code class="function">jsonb_to_recordset</code> ( <code class="type">jsonb</code> )
→ <code class="returnvalue">setof record</code>
</p>
<p>
Expands the top-level JSON array of objects to a set of rows having
the composite type defined by an <code class="literal">AS</code> clause. (As
with all functions returning <code class="type">record</code>, the calling query
must explicitly define the structure of the record with
an <code class="literal">AS</code> clause.) Each element of the JSON array is
processed as described above
for <code class="function">json[b]_populate_record</code>.
</p>
<p>
<code class="literal">select * from json_to_recordset('[{"a":1,"b":"foo"}, {"a":"2","c":"bar"}]') as x(a int, b text)</code>
→ <code class="returnvalue"></code>
</p><pre class="programlisting">
a | b
---+-----
1 | foo
2 |
</pre><p>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.13.1.1.1" class="indexterm"></a>
<code class="function">jsonb_set</code> ( <em class="parameter"><code>target</code></em> <code class="type">jsonb</code>, <em class="parameter"><code>path</code></em> <code class="type">text[]</code>, <em class="parameter"><code>new_value</code></em> <code class="type">jsonb</code> [<span class="optional">, <em class="parameter"><code>create_if_missing</code></em> <code class="type">boolean</code> </span>] )
→ <code class="returnvalue">jsonb</code>
</p>
<p>
Returns <em class="parameter"><code>target</code></em>
with the item designated by <em class="parameter"><code>path</code></em>
replaced by <em class="parameter"><code>new_value</code></em>, or with
<em class="parameter"><code>new_value</code></em> added if
<em class="parameter"><code>create_if_missing</code></em> is true (which is the
default) and the item designated by <em class="parameter"><code>path</code></em>
does not exist.
All earlier steps in the path must exist, or
the <em class="parameter"><code>target</code></em> is returned unchanged.
As with the path oriented operators, negative integers that
appear in the <em class="parameter"><code>path</code></em> count from the end
of JSON arrays.
If the last path step is an array index that is out of range,
and <em class="parameter"><code>create_if_missing</code></em> is true, the new
value is added at the beginning of the array if the index is negative,
or at the end of the array if it is positive.
</p>
<p>
<code class="literal">jsonb_set('[{"f1":1,"f2":null},2,null,3]', '{0,f1}', '[2,3,4]', false)</code>
→ <code class="returnvalue">[{"f1": [2, 3, 4], "f2": null}, 2, null, 3]</code>
</p>
<p>
<code class="literal">jsonb_set('[{"f1":1,"f2":null},2]', '{0,f3}', '[2,3,4]')</code>
→ <code class="returnvalue">[{"f1": 1, "f2": null, "f3": [2, 3, 4]}, 2]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.14.1.1.1" class="indexterm"></a>
<code class="function">jsonb_set_lax</code> ( <em class="parameter"><code>target</code></em> <code class="type">jsonb</code>, <em class="parameter"><code>path</code></em> <code class="type">text[]</code>, <em class="parameter"><code>new_value</code></em> <code class="type">jsonb</code> [<span class="optional">, <em class="parameter"><code>create_if_missing</code></em> <code class="type">boolean</code> [<span class="optional">, <em class="parameter"><code>null_value_treatment</code></em> <code class="type">text</code> </span>]</span>] )
→ <code class="returnvalue">jsonb</code>
</p>
<p>
If <em class="parameter"><code>new_value</code></em> is not <code class="literal">NULL</code>,
behaves identically to <code class="literal">jsonb_set</code>. Otherwise behaves
according to the value
of <em class="parameter"><code>null_value_treatment</code></em> which must be one
of <code class="literal">'raise_exception'</code>,
<code class="literal">'use_json_null'</code>, <code class="literal">'delete_key'</code>, or
<code class="literal">'return_target'</code>. The default is
<code class="literal">'use_json_null'</code>.
</p>
<p>
<code class="literal">jsonb_set_lax('[{"f1":1,"f2":null},2,null,3]', '{0,f1}', null)</code>
→ <code class="returnvalue">[{"f1": null, "f2": null}, 2, null, 3]</code>
</p>
<p>
<code class="literal">jsonb_set_lax('[{"f1":99,"f2":null},2]', '{0,f3}', null, true, 'return_target')</code>
→ <code class="returnvalue">[{"f1": 99, "f2": null}, 2]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.15.1.1.1" class="indexterm"></a>
<code class="function">jsonb_insert</code> ( <em class="parameter"><code>target</code></em> <code class="type">jsonb</code>, <em class="parameter"><code>path</code></em> <code class="type">text[]</code>, <em class="parameter"><code>new_value</code></em> <code class="type">jsonb</code> [<span class="optional">, <em class="parameter"><code>insert_after</code></em> <code class="type">boolean</code> </span>] )
→ <code class="returnvalue">jsonb</code>
</p>
<p>
Returns <em class="parameter"><code>target</code></em>
with <em class="parameter"><code>new_value</code></em> inserted. If the item
designated by the <em class="parameter"><code>path</code></em> is an array
element, <em class="parameter"><code>new_value</code></em> will be inserted before
that item if <em class="parameter"><code>insert_after</code></em> is false (which
is the default), or after it
if <em class="parameter"><code>insert_after</code></em> is true. If the item
designated by the <em class="parameter"><code>path</code></em> is an object
field, <em class="parameter"><code>new_value</code></em> will be inserted only if
the object does not already contain that key.
All earlier steps in the path must exist, or
the <em class="parameter"><code>target</code></em> is returned unchanged.
As with the path oriented operators, negative integers that
appear in the <em class="parameter"><code>path</code></em> count from the end
of JSON arrays.
If the last path step is an array index that is out of range, the new
value is added at the beginning of the array if the index is negative,
or at the end of the array if it is positive.
</p>
<p>
<code class="literal">jsonb_insert('{"a": [0,1,2]}', '{a, 1}', '"new_value"')</code>
→ <code class="returnvalue">{"a": [0, "new_value", 1, 2]}</code>
</p>
<p>
<code class="literal">jsonb_insert('{"a": [0,1,2]}', '{a, 1}', '"new_value"', true)</code>
→ <code class="returnvalue">{"a": [0, 1, "new_value", 2]}</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.16.1.1.1" class="indexterm"></a>
<code class="function">json_strip_nulls</code> ( <code class="type">json</code> )
→ <code class="returnvalue">json</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.16.1.2.1" class="indexterm"></a>
<code class="function">jsonb_strip_nulls</code> ( <code class="type">jsonb</code> )
→ <code class="returnvalue">jsonb</code>
</p>
<p>
Deletes all object fields that have null values from the given JSON
value, recursively. Null values that are not object fields are
untouched.
</p>
<p>
<code class="literal">json_strip_nulls('[{"f1":1, "f2":null}, 2, null, 3]')</code>
→ <code class="returnvalue">[{"f1":1},2,null,3]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.17.1.1.1" class="indexterm"></a>
<code class="function">jsonb_path_exists</code> ( <em class="parameter"><code>target</code></em> <code class="type">jsonb</code>, <em class="parameter"><code>path</code></em> <code class="type">jsonpath</code> [<span class="optional">, <em class="parameter"><code>vars</code></em> <code class="type">jsonb</code> [<span class="optional">, <em class="parameter"><code>silent</code></em> <code class="type">boolean</code> </span>]</span>] )
→ <code class="returnvalue">boolean</code>
</p>
<p>
Checks whether the JSON path returns any item for the specified JSON
value.
If the <em class="parameter"><code>vars</code></em> argument is specified, it must
be a JSON object, and its fields provide named values to be
substituted into the <code class="type">jsonpath</code> expression.
If the <em class="parameter"><code>silent</code></em> argument is specified and
is <code class="literal">true</code>, the function suppresses the same errors
as the <code class="literal">@?</code> and <code class="literal">@@</code> operators do.
</p>
<p>
<code class="literal">jsonb_path_exists('{"a":[1,2,3,4,5]}', '$.a[*] ? (@ >= $min && @ <= $max)', '{"min":2, "max":4}')</code>
→ <code class="returnvalue">t</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.18.1.1.1" class="indexterm"></a>
<code class="function">jsonb_path_match</code> ( <em class="parameter"><code>target</code></em> <code class="type">jsonb</code>, <em class="parameter"><code>path</code></em> <code class="type">jsonpath</code> [<span class="optional">, <em class="parameter"><code>vars</code></em> <code class="type">jsonb</code> [<span class="optional">, <em class="parameter"><code>silent</code></em> <code class="type">boolean</code> </span>]</span>] )
→ <code class="returnvalue">boolean</code>
</p>
<p>
Returns the result of a JSON path predicate check for the specified
JSON value. Only the first item of the result is taken into account.
If the result is not Boolean, then <code class="literal">NULL</code> is returned.
The optional <em class="parameter"><code>vars</code></em>
and <em class="parameter"><code>silent</code></em> arguments act the same as
for <code class="function">jsonb_path_exists</code>.
</p>
<p>
<code class="literal">jsonb_path_match('{"a":[1,2,3,4,5]}', 'exists($.a[*] ? (@ >= $min && @ <= $max))', '{"min":2, "max":4}')</code>
→ <code class="returnvalue">t</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.19.1.1.1" class="indexterm"></a>
<code class="function">jsonb_path_query</code> ( <em class="parameter"><code>target</code></em> <code class="type">jsonb</code>, <em class="parameter"><code>path</code></em> <code class="type">jsonpath</code> [<span class="optional">, <em class="parameter"><code>vars</code></em> <code class="type">jsonb</code> [<span class="optional">, <em class="parameter"><code>silent</code></em> <code class="type">boolean</code> </span>]</span>] )
→ <code class="returnvalue">setof jsonb</code>
</p>
<p>
Returns all JSON items returned by the JSON path for the specified
JSON value.
The optional <em class="parameter"><code>vars</code></em>
and <em class="parameter"><code>silent</code></em> arguments act the same as
for <code class="function">jsonb_path_exists</code>.
</p>
<p>
<code class="literal">select * from jsonb_path_query('{"a":[1,2,3,4,5]}', '$.a[*] ? (@ >= $min && @ <= $max)', '{"min":2, "max":4}')</code>
→ <code class="returnvalue"></code>
</p><pre class="programlisting">
jsonb_path_query
------------------
2
3
4
</pre><p>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.20.1.1.1" class="indexterm"></a>
<code class="function">jsonb_path_query_array</code> ( <em class="parameter"><code>target</code></em> <code class="type">jsonb</code>, <em class="parameter"><code>path</code></em> <code class="type">jsonpath</code> [<span class="optional">, <em class="parameter"><code>vars</code></em> <code class="type">jsonb</code> [<span class="optional">, <em class="parameter"><code>silent</code></em> <code class="type">boolean</code> </span>]</span>] )
→ <code class="returnvalue">jsonb</code>
</p>
<p>
Returns all JSON items returned by the JSON path for the specified
JSON value, as a JSON array.
The optional <em class="parameter"><code>vars</code></em>
and <em class="parameter"><code>silent</code></em> arguments act the same as
for <code class="function">jsonb_path_exists</code>.
</p>
<p>
<code class="literal">jsonb_path_query_array('{"a":[1,2,3,4,5]}', '$.a[*] ? (@ >= $min && @ <= $max)', '{"min":2, "max":4}')</code>
→ <code class="returnvalue">[2, 3, 4]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.21.1.1.1" class="indexterm"></a>
<code class="function">jsonb_path_query_first</code> ( <em class="parameter"><code>target</code></em> <code class="type">jsonb</code>, <em class="parameter"><code>path</code></em> <code class="type">jsonpath</code> [<span class="optional">, <em class="parameter"><code>vars</code></em> <code class="type">jsonb</code> [<span class="optional">, <em class="parameter"><code>silent</code></em> <code class="type">boolean</code> </span>]</span>] )
→ <code class="returnvalue">jsonb</code>
</p>
<p>
Returns the first JSON item returned by the JSON path for the
specified JSON value. Returns <code class="literal">NULL</code> if there are no
results.
The optional <em class="parameter"><code>vars</code></em>
and <em class="parameter"><code>silent</code></em> arguments act the same as
for <code class="function">jsonb_path_exists</code>.
</p>
<p>
<code class="literal">jsonb_path_query_first('{"a":[1,2,3,4,5]}', '$.a[*] ? (@ >= $min && @ <= $max)', '{"min":2, "max":4}')</code>
→ <code class="returnvalue">2</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.22.1.1.1" class="indexterm"></a>
<code class="function">jsonb_path_exists_tz</code> ( <em class="parameter"><code>target</code></em> <code class="type">jsonb</code>, <em class="parameter"><code>path</code></em> <code class="type">jsonpath</code> [<span class="optional">, <em class="parameter"><code>vars</code></em> <code class="type">jsonb</code> [<span class="optional">, <em class="parameter"><code>silent</code></em> <code class="type">boolean</code> </span>]</span>] )
→ <code class="returnvalue">boolean</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.22.1.2.1" class="indexterm"></a>
<code class="function">jsonb_path_match_tz</code> ( <em class="parameter"><code>target</code></em> <code class="type">jsonb</code>, <em class="parameter"><code>path</code></em> <code class="type">jsonpath</code> [<span class="optional">, <em class="parameter"><code>vars</code></em> <code class="type">jsonb</code> [<span class="optional">, <em class="parameter"><code>silent</code></em> <code class="type">boolean</code> </span>]</span>] )
→ <code class="returnvalue">boolean</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.22.1.3.1" class="indexterm"></a>
<code class="function">jsonb_path_query_tz</code> ( <em class="parameter"><code>target</code></em> <code class="type">jsonb</code>, <em class="parameter"><code>path</code></em> <code class="type">jsonpath</code> [<span class="optional">, <em class="parameter"><code>vars</code></em> <code class="type">jsonb</code> [<span class="optional">, <em class="parameter"><code>silent</code></em> <code class="type">boolean</code> </span>]</span>] )
→ <code class="returnvalue">setof jsonb</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.22.1.4.1" class="indexterm"></a>
<code class="function">jsonb_path_query_array_tz</code> ( <em class="parameter"><code>target</code></em> <code class="type">jsonb</code>, <em class="parameter"><code>path</code></em> <code class="type">jsonpath</code> [<span class="optional">, <em class="parameter"><code>vars</code></em> <code class="type">jsonb</code> [<span class="optional">, <em class="parameter"><code>silent</code></em> <code class="type">boolean</code> </span>]</span>] )
→ <code class="returnvalue">jsonb</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.22.1.5.1" class="indexterm"></a>
<code class="function">jsonb_path_query_first_tz</code> ( <em class="parameter"><code>target</code></em> <code class="type">jsonb</code>, <em class="parameter"><code>path</code></em> <code class="type">jsonpath</code> [<span class="optional">, <em class="parameter"><code>vars</code></em> <code class="type">jsonb</code> [<span class="optional">, <em class="parameter"><code>silent</code></em> <code class="type">boolean</code> </span>]</span>] )
→ <code class="returnvalue">jsonb</code>
</p>
<p>
These functions act like their counterparts described above without
the <code class="literal">_tz</code> suffix, except that these functions support
comparisons of date/time values that require timezone-aware
conversions. The example below requires interpretation of the
date-only value <code class="literal">2015-08-02</code> as a timestamp with time
zone, so the result depends on the current
<a class="xref" href="runtime-config-client.html#GUC-TIMEZONE">TimeZone</a> setting. Due to this dependency, these
functions are marked as stable, which means these functions cannot be
used in indexes. Their counterparts are immutable, and so can be used
in indexes; but they will throw errors if asked to make such
comparisons.
</p>
<p>
<code class="literal">jsonb_path_exists_tz('["2015-08-01 12:00:00-05"]', '$[*] ? (@.datetime() < "2015-08-02".datetime())')</code>
→ <code class="returnvalue">t</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.23.1.1.1" class="indexterm"></a>
<code class="function">jsonb_pretty</code> ( <code class="type">jsonb</code> )
→ <code class="returnvalue">text</code>
</p>
<p>
Converts the given JSON value to pretty-printed, indented text.
</p>
<p>
<code class="literal">jsonb_pretty('[{"f1":1,"f2":null}, 2]')</code>
→ <code class="returnvalue"></code>
</p><pre class="programlisting">
[
{
"f1": 1,
"f2": null
},
2
]
</pre><p>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.24.1.1.1" class="indexterm"></a>
<code class="function">json_typeof</code> ( <code class="type">json</code> )
→ <code class="returnvalue">text</code>
</p>
<p class="func_signature">
<a id="id-1.5.8.22.8.13.2.2.24.1.2.1" class="indexterm"></a>
<code class="function">jsonb_typeof</code> ( <code class="type">jsonb</code> )
→ <code class="returnvalue">text</code>
</p>
<p>
Returns the type of the top-level JSON value as a text string.
Possible types are
<code class="literal">object</code>, <code class="literal">array</code>,
<code class="literal">string</code>, <code class="literal">number</code>,
<code class="literal">boolean</code>, and <code class="literal">null</code>.
(The <code class="literal">null</code> result should not be confused
with an SQL NULL; see the examples.)
</p>
<p>
<code class="literal">json_typeof('-123.4')</code>
→ <code class="returnvalue">number</code>
</p>
<p>
<code class="literal">json_typeof('null'::json)</code>
→ <code class="returnvalue">null</code>
</p>
<p>
<code class="literal">json_typeof(NULL::json) IS NULL</code>
→ <code class="returnvalue">t</code>
</p></td></tr></tbody></table></div></div><br class="table-break" /></div><div class="sect2" id="FUNCTIONS-SQLJSON-PATH"><div class="titlepage"><div><div><h3 class="title">9.16.2. The SQL/JSON Path Language <a href="#FUNCTIONS-SQLJSON-PATH" class="id_link">#</a></h3></div></div></div><a id="id-1.5.8.22.9.2" class="indexterm"></a><p>
SQL/JSON path expressions specify the items to be retrieved
from the JSON data, similar to XPath expressions used
for SQL access to XML. In <span class="productname">PostgreSQL</span>,
path expressions are implemented as the <code class="type">jsonpath</code>
data type and can use any elements described in
<a class="xref" href="datatype-json.html#DATATYPE-JSONPATH" title="8.14.7. jsonpath Type">Section 8.14.7</a>.
</p><p>
JSON query functions and operators
pass the provided path expression to the <em class="firstterm">path engine</em>
for evaluation. If the expression matches the queried JSON data,
the corresponding JSON item, or set of items, is returned.
Path expressions are written in the SQL/JSON path language
and can include arithmetic expressions and functions.
</p><p>
A path expression consists of a sequence of elements allowed
by the <code class="type">jsonpath</code> data type.
The path expression is normally evaluated from left to right, but
you can use parentheses to change the order of operations.
If the evaluation is successful, a sequence of JSON items is produced,
and the evaluation result is returned to the JSON query function
that completes the specified computation.
</p><p>
To refer to the JSON value being queried (the
<em class="firstterm">context item</em>), use the <code class="literal">$</code> variable
in the path expression. It can be followed by one or more
<a class="link" href="datatype-json.html#TYPE-JSONPATH-ACCESSORS" title="Table 8.25. jsonpath Accessors">accessor operators</a>,
which go down the JSON structure level by level to retrieve sub-items
of the context item. Each operator that follows deals with the
result of the previous evaluation step.
</p><p>
For example, suppose you have some JSON data from a GPS tracker that you
would like to parse, such as:
</p><pre class="programlisting">
{
"track": {
"segments": [
{
"location": [ 47.763, 13.4034 ],
"start time": "2018-10-14 10:05:14",
"HR": 73
},
{
"location": [ 47.706, 13.2635 ],
"start time": "2018-10-14 10:39:21",
"HR": 135
}
]
}
}
</pre><p>
</p><p>
To retrieve the available track segments, you need to use the
<code class="literal">.<em class="replaceable"><code>key</code></em></code> accessor
operator to descend through surrounding JSON objects:
</p><pre class="programlisting">
$.track.segments
</pre><p>
</p><p>
To retrieve the contents of an array, you typically use the
<code class="literal">[*]</code> operator. For example,
the following path will return the location coordinates for all
the available track segments:
</p><pre class="programlisting">
$.track.segments[*].location
</pre><p>
</p><p>
To return the coordinates of the first segment only, you can
specify the corresponding subscript in the <code class="literal">[]</code>
accessor operator. Recall that JSON array indexes are 0-relative:
</p><pre class="programlisting">
$.track.segments[0].location
</pre><p>
</p><p>
The result of each path evaluation step can be processed
by one or more <code class="type">jsonpath</code> operators and methods
listed in <a class="xref" href="functions-json.html#FUNCTIONS-SQLJSON-PATH-OPERATORS" title="9.16.2.2. SQL/JSON Path Operators and Methods">Section 9.16.2.2</a>.
Each method name must be preceded by a dot. For example,
you can get the size of an array:
</p><pre class="programlisting">
$.track.segments.size()
</pre><p>
More examples of using <code class="type">jsonpath</code> operators
and methods within path expressions appear below in
<a class="xref" href="functions-json.html#FUNCTIONS-SQLJSON-PATH-OPERATORS" title="9.16.2.2. SQL/JSON Path Operators and Methods">Section 9.16.2.2</a>.
</p><p>
When defining a path, you can also use one or more
<em class="firstterm">filter expressions</em> that work similarly to the
<code class="literal">WHERE</code> clause in SQL. A filter expression begins with
a question mark and provides a condition in parentheses:
</p><pre class="programlisting">
? (<em class="replaceable"><code>condition</code></em>)
</pre><p>
</p><p>
Filter expressions must be written just after the path evaluation step
to which they should apply. The result of that step is filtered to include
only those items that satisfy the provided condition. SQL/JSON defines
three-valued logic, so the condition can be <code class="literal">true</code>, <code class="literal">false</code>,
or <code class="literal">unknown</code>. The <code class="literal">unknown</code> value
plays the same role as SQL <code class="literal">NULL</code> and can be tested
for with the <code class="literal">is unknown</code> predicate. Further path
evaluation steps use only those items for which the filter expression
returned <code class="literal">true</code>.
</p><p>
The functions and operators that can be used in filter expressions are
listed in <a class="xref" href="functions-json.html#FUNCTIONS-SQLJSON-FILTER-EX-TABLE" title="Table 9.51. jsonpath Filter Expression Elements">Table 9.51</a>. Within a
filter expression, the <code class="literal">@</code> variable denotes the value
being filtered (i.e., one result of the preceding path step). You can
write accessor operators after <code class="literal">@</code> to retrieve component
items.
</p><p>
For example, suppose you would like to retrieve all heart rate values higher
than 130. You can achieve this using the following expression:
</p><pre class="programlisting">
$.track.segments[*].HR ? (@ > 130)
</pre><p>
</p><p>
To get the start times of segments with such values, you have to
filter out irrelevant segments before returning the start times, so the
filter expression is applied to the previous step, and the path used
in the condition is different:
</p><pre class="programlisting">
$.track.segments[*] ? (@.HR > 130)."start time"
</pre><p>
</p><p>
You can use several filter expressions in sequence, if required. For
example, the following expression selects start times of all segments that
contain locations with relevant coordinates and high heart rate values:
</p><pre class="programlisting">
$.track.segments[*] ? (@.location[1] < 13.4) ? (@.HR > 130)."start time"
</pre><p>
</p><p>
Using filter expressions at different nesting levels is also allowed.
The following example first filters all segments by location, and then
returns high heart rate values for these segments, if available:
</p><pre class="programlisting">
$.track.segments[*] ? (@.location[1] < 13.4).HR ? (@ > 130)
</pre><p>
</p><p>
You can also nest filter expressions within each other:
</p><pre class="programlisting">
$.track ? (exists(@.segments[*] ? (@.HR > 130))).segments.size()
</pre><p>
This expression returns the size of the track if it contains any
segments with high heart rate values, or an empty sequence otherwise.
</p><p>
<span class="productname">PostgreSQL</span>'s implementation of the SQL/JSON path
language has the following deviations from the SQL/JSON standard:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
A path expression can be a Boolean predicate, although the SQL/JSON
standard allows predicates only in filters. This is necessary for
implementation of the <code class="literal">@@</code> operator. For example,
the following <code class="type">jsonpath</code> expression is valid in
<span class="productname">PostgreSQL</span>:
</p><pre class="programlisting">
$.track.segments[*].HR < 70
</pre><p>
</p></li><li class="listitem"><p>
There are minor differences in the interpretation of regular
expression patterns used in <code class="literal">like_regex</code> filters, as
described in <a class="xref" href="functions-json.html#JSONPATH-REGULAR-EXPRESSIONS" title="9.16.2.3. SQL/JSON Regular Expressions">Section 9.16.2.3</a>.
</p></li></ul></div><div class="sect3" id="STRICT-AND-LAX-MODES"><div class="titlepage"><div><div><h4 class="title">9.16.2.1. Strict and Lax Modes <a href="#STRICT-AND-LAX-MODES" class="id_link">#</a></h4></div></div></div><p>
When you query JSON data, the path expression may not match the
actual JSON data structure. An attempt to access a non-existent
member of an object or element of an array results in a
structural error. SQL/JSON path expressions have two modes
of handling structural errors:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
lax (default) — the path engine implicitly adapts
the queried data to the specified path.
Any remaining structural errors are suppressed and converted
to empty SQL/JSON sequences.
</p></li><li class="listitem"><p>
strict — if a structural error occurs, an error is raised.
</p></li></ul></div><p>
The lax mode facilitates matching of a JSON document structure and path
expression if the JSON data does not conform to the expected schema.
If an operand does not match the requirements of a particular operation,
it can be automatically wrapped as an SQL/JSON array or unwrapped by
converting its elements into an SQL/JSON sequence before performing
this operation. Besides, comparison operators automatically unwrap their
operands in the lax mode, so you can compare SQL/JSON arrays
out-of-the-box. An array of size 1 is considered equal to its sole element.
Automatic unwrapping is not performed only when:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
The path expression contains <code class="literal">type()</code> or
<code class="literal">size()</code> methods that return the type
and the number of elements in the array, respectively.
</p></li><li class="listitem"><p>
The queried JSON data contain nested arrays. In this case, only
the outermost array is unwrapped, while all the inner arrays
remain unchanged. Thus, implicit unwrapping can only go one
level down within each path evaluation step.
</p></li></ul></div><p>
</p><p>
For example, when querying the GPS data listed above, you can
abstract from the fact that it stores an array of segments
when using the lax mode:
</p><pre class="programlisting">
lax $.track.segments.location
</pre><p>
</p><p>
In the strict mode, the specified path must exactly match the structure of
the queried JSON document to return an SQL/JSON item, so using this
path expression will cause an error. To get the same result as in
the lax mode, you have to explicitly unwrap the
<code class="literal">segments</code> array:
</p><pre class="programlisting">
strict $.track.segments[*].location
</pre><p>
</p><p>
The <code class="literal">.**</code> accessor can lead to surprising results
when using the lax mode. For instance, the following query selects every
<code class="literal">HR</code> value twice:
</p><pre class="programlisting">
lax $.**.HR
</pre><p>
This happens because the <code class="literal">.**</code> accessor selects both
the <code class="literal">segments</code> array and each of its elements, while
the <code class="literal">.HR</code> accessor automatically unwraps arrays when
using the lax mode. To avoid surprising results, we recommend using
the <code class="literal">.**</code> accessor only in the strict mode. The
following query selects each <code class="literal">HR</code> value just once:
</p><pre class="programlisting">
strict $.**.HR
</pre><p>
</p></div><div class="sect3" id="FUNCTIONS-SQLJSON-PATH-OPERATORS"><div class="titlepage"><div><div><h4 class="title">9.16.2.2. SQL/JSON Path Operators and Methods <a href="#FUNCTIONS-SQLJSON-PATH-OPERATORS" class="id_link">#</a></h4></div></div></div><p>
<a class="xref" href="functions-json.html#FUNCTIONS-SQLJSON-OP-TABLE" title="Table 9.50. jsonpath Operators and Methods">Table 9.50</a> shows the operators and
methods available in <code class="type">jsonpath</code>. Note that while the unary
operators and methods can be applied to multiple values resulting from a
preceding path step, the binary operators (addition etc.) can only be
applied to single values.
</p><div class="table" id="FUNCTIONS-SQLJSON-OP-TABLE"><p class="title"><strong>Table 9.50. <code class="type">jsonpath</code> Operators and Methods</strong></p><div class="table-contents"><table class="table" summary="jsonpath Operators and Methods" border="1"><colgroup><col /></colgroup><thead><tr><th class="func_table_entry"><p class="func_signature">
Operator/Method
</p>
<p>
Description
</p>
<p>
Example(s)
</p></th></tr></thead><tbody><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>number</code></em> <code class="literal">+</code> <em class="replaceable"><code>number</code></em>
→ <code class="returnvalue"><em class="replaceable"><code>number</code></em></code>
</p>
<p>
Addition
</p>
<p>
<code class="literal">jsonb_path_query('[2]', '$[0] + 3')</code>
→ <code class="returnvalue">5</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="literal">+</code> <em class="replaceable"><code>number</code></em>
→ <code class="returnvalue"><em class="replaceable"><code>number</code></em></code>
</p>
<p>
Unary plus (no operation); unlike addition, this can iterate over
multiple values
</p>
<p>
<code class="literal">jsonb_path_query_array('{"x": [2,3,4]}', '+ $.x')</code>
→ <code class="returnvalue">[2, 3, 4]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>number</code></em> <code class="literal">-</code> <em class="replaceable"><code>number</code></em>
→ <code class="returnvalue"><em class="replaceable"><code>number</code></em></code>
</p>
<p>
Subtraction
</p>
<p>
<code class="literal">jsonb_path_query('[2]', '7 - $[0]')</code>
→ <code class="returnvalue">5</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="literal">-</code> <em class="replaceable"><code>number</code></em>
→ <code class="returnvalue"><em class="replaceable"><code>number</code></em></code>
</p>
<p>
Negation; unlike subtraction, this can iterate over
multiple values
</p>
<p>
<code class="literal">jsonb_path_query_array('{"x": [2,3,4]}', '- $.x')</code>
→ <code class="returnvalue">[-2, -3, -4]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>number</code></em> <code class="literal">*</code> <em class="replaceable"><code>number</code></em>
→ <code class="returnvalue"><em class="replaceable"><code>number</code></em></code>
</p>
<p>
Multiplication
</p>
<p>
<code class="literal">jsonb_path_query('[4]', '2 * $[0]')</code>
→ <code class="returnvalue">8</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>number</code></em> <code class="literal">/</code> <em class="replaceable"><code>number</code></em>
→ <code class="returnvalue"><em class="replaceable"><code>number</code></em></code>
</p>
<p>
Division
</p>
<p>
<code class="literal">jsonb_path_query('[8.5]', '$[0] / 2')</code>
→ <code class="returnvalue">4.2500000000000000</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>number</code></em> <code class="literal">%</code> <em class="replaceable"><code>number</code></em>
→ <code class="returnvalue"><em class="replaceable"><code>number</code></em></code>
</p>
<p>
Modulo (remainder)
</p>
<p>
<code class="literal">jsonb_path_query('[32]', '$[0] % 10')</code>
→ <code class="returnvalue">2</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>value</code></em> <code class="literal">.</code> <code class="literal">type()</code>
→ <code class="returnvalue"><em class="replaceable"><code>string</code></em></code>
</p>
<p>
Type of the JSON item (see <code class="function">json_typeof</code>)
</p>
<p>
<code class="literal">jsonb_path_query_array('[1, "2", {}]', '$[*].type()')</code>
→ <code class="returnvalue">["number", "string", "object"]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>value</code></em> <code class="literal">.</code> <code class="literal">size()</code>
→ <code class="returnvalue"><em class="replaceable"><code>number</code></em></code>
</p>
<p>
Size of the JSON item (number of array elements, or 1 if not an
array)
</p>
<p>
<code class="literal">jsonb_path_query('{"m": [11, 15]}', '$.m.size()')</code>
→ <code class="returnvalue">2</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>value</code></em> <code class="literal">.</code> <code class="literal">double()</code>
→ <code class="returnvalue"><em class="replaceable"><code>number</code></em></code>
</p>
<p>
Approximate floating-point number converted from a JSON number or
string
</p>
<p>
<code class="literal">jsonb_path_query('{"len": "1.9"}', '$.len.double() * 2')</code>
→ <code class="returnvalue">3.8</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>number</code></em> <code class="literal">.</code> <code class="literal">ceiling()</code>
→ <code class="returnvalue"><em class="replaceable"><code>number</code></em></code>
</p>
<p>
Nearest integer greater than or equal to the given number
</p>
<p>
<code class="literal">jsonb_path_query('{"h": 1.3}', '$.h.ceiling()')</code>
→ <code class="returnvalue">2</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>number</code></em> <code class="literal">.</code> <code class="literal">floor()</code>
→ <code class="returnvalue"><em class="replaceable"><code>number</code></em></code>
</p>
<p>
Nearest integer less than or equal to the given number
</p>
<p>
<code class="literal">jsonb_path_query('{"h": 1.7}', '$.h.floor()')</code>
→ <code class="returnvalue">1</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>number</code></em> <code class="literal">.</code> <code class="literal">abs()</code>
→ <code class="returnvalue"><em class="replaceable"><code>number</code></em></code>
</p>
<p>
Absolute value of the given number
</p>
<p>
<code class="literal">jsonb_path_query('{"z": -0.3}', '$.z.abs()')</code>
→ <code class="returnvalue">0.3</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>string</code></em> <code class="literal">.</code> <code class="literal">datetime()</code>
→ <code class="returnvalue"><em class="replaceable"><code>datetime_type</code></em></code>
(see note)
</p>
<p>
Date/time value converted from a string
</p>
<p>
<code class="literal">jsonb_path_query('["2015-8-1", "2015-08-12"]', '$[*] ? (@.datetime() < "2015-08-2".datetime())')</code>
→ <code class="returnvalue">"2015-8-1"</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>string</code></em> <code class="literal">.</code> <code class="literal">datetime(<em class="replaceable"><code>template</code></em>)</code>
→ <code class="returnvalue"><em class="replaceable"><code>datetime_type</code></em></code>
(see note)
</p>
<p>
Date/time value converted from a string using the
specified <code class="function">to_timestamp</code> template
</p>
<p>
<code class="literal">jsonb_path_query_array('["12:30", "18:40"]', '$[*].datetime("HH24:MI")')</code>
→ <code class="returnvalue">["12:30:00", "18:40:00"]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>object</code></em> <code class="literal">.</code> <code class="literal">keyvalue()</code>
→ <code class="returnvalue"><em class="replaceable"><code>array</code></em></code>
</p>
<p>
The object's key-value pairs, represented as an array of objects
containing three fields: <code class="literal">"key"</code>,
<code class="literal">"value"</code>, and <code class="literal">"id"</code>;
<code class="literal">"id"</code> is a unique identifier of the object the
key-value pair belongs to
</p>
<p>
<code class="literal">jsonb_path_query_array('{"x": "20", "y": 32}', '$.keyvalue()')</code>
→ <code class="returnvalue">[{"id": 0, "key": "x", "value": "20"}, {"id": 0, "key": "y", "value": 32}]</code>
</p></td></tr></tbody></table></div></div><br class="table-break" /><div class="note"><h3 class="title">Note</h3><p>
The result type of the <code class="literal">datetime()</code> and
<code class="literal">datetime(<em class="replaceable"><code>template</code></em>)</code>
methods can be <code class="type">date</code>, <code class="type">timetz</code>, <code class="type">time</code>,
<code class="type">timestamptz</code>, or <code class="type">timestamp</code>.
Both methods determine their result type dynamically.
</p><p>
The <code class="literal">datetime()</code> method sequentially tries to
match its input string to the ISO formats
for <code class="type">date</code>, <code class="type">timetz</code>, <code class="type">time</code>,
<code class="type">timestamptz</code>, and <code class="type">timestamp</code>. It stops on
the first matching format and emits the corresponding data type.
</p><p>
The <code class="literal">datetime(<em class="replaceable"><code>template</code></em>)</code>
method determines the result type according to the fields used in the
provided template string.
</p><p>
The <code class="literal">datetime()</code> and
<code class="literal">datetime(<em class="replaceable"><code>template</code></em>)</code> methods
use the same parsing rules as the <code class="literal">to_timestamp</code> SQL
function does (see <a class="xref" href="functions-formatting.html" title="9.8. Data Type Formatting Functions">Section 9.8</a>), with three
exceptions. First, these methods don't allow unmatched template
patterns. Second, only the following separators are allowed in the
template string: minus sign, period, solidus (slash), comma, apostrophe,
semicolon, colon and space. Third, separators in the template string
must exactly match the input string.
</p><p>
If different date/time types need to be compared, an implicit cast is
applied. A <code class="type">date</code> value can be cast to <code class="type">timestamp</code>
or <code class="type">timestamptz</code>, <code class="type">timestamp</code> can be cast to
<code class="type">timestamptz</code>, and <code class="type">time</code> to <code class="type">timetz</code>.
However, all but the first of these conversions depend on the current
<a class="xref" href="runtime-config-client.html#GUC-TIMEZONE">TimeZone</a> setting, and thus can only be performed
within timezone-aware <code class="type">jsonpath</code> functions.
</p></div><p>
<a class="xref" href="functions-json.html#FUNCTIONS-SQLJSON-FILTER-EX-TABLE" title="Table 9.51. jsonpath Filter Expression Elements">Table 9.51</a> shows the available
filter expression elements.
</p><div class="table" id="FUNCTIONS-SQLJSON-FILTER-EX-TABLE"><p class="title"><strong>Table 9.51. <code class="type">jsonpath</code> Filter Expression Elements</strong></p><div class="table-contents"><table class="table" summary="jsonpath Filter Expression Elements" border="1"><colgroup><col /></colgroup><thead><tr><th class="func_table_entry"><p class="func_signature">
Predicate/Value
</p>
<p>
Description
</p>
<p>
Example(s)
</p></th></tr></thead><tbody><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>value</code></em> <code class="literal">==</code> <em class="replaceable"><code>value</code></em>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Equality comparison (this, and the other comparison operators, work on
all JSON scalar values)
</p>
<p>
<code class="literal">jsonb_path_query_array('[1, "a", 1, 3]', '$[*] ? (@ == 1)')</code>
→ <code class="returnvalue">[1, 1]</code>
</p>
<p>
<code class="literal">jsonb_path_query_array('[1, "a", 1, 3]', '$[*] ? (@ == "a")')</code>
→ <code class="returnvalue">["a"]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>value</code></em> <code class="literal">!=</code> <em class="replaceable"><code>value</code></em>
→ <code class="returnvalue">boolean</code>
</p>
<p class="func_signature">
<em class="replaceable"><code>value</code></em> <code class="literal"><></code> <em class="replaceable"><code>value</code></em>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Non-equality comparison
</p>
<p>
<code class="literal">jsonb_path_query_array('[1, 2, 1, 3]', '$[*] ? (@ != 1)')</code>
→ <code class="returnvalue">[2, 3]</code>
</p>
<p>
<code class="literal">jsonb_path_query_array('["a", "b", "c"]', '$[*] ? (@ <> "b")')</code>
→ <code class="returnvalue">["a", "c"]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>value</code></em> <code class="literal"><</code> <em class="replaceable"><code>value</code></em>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Less-than comparison
</p>
<p>
<code class="literal">jsonb_path_query_array('[1, 2, 3]', '$[*] ? (@ < 2)')</code>
→ <code class="returnvalue">[1]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>value</code></em> <code class="literal"><=</code> <em class="replaceable"><code>value</code></em>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Less-than-or-equal-to comparison
</p>
<p>
<code class="literal">jsonb_path_query_array('["a", "b", "c"]', '$[*] ? (@ <= "b")')</code>
→ <code class="returnvalue">["a", "b"]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>value</code></em> <code class="literal">></code> <em class="replaceable"><code>value</code></em>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Greater-than comparison
</p>
<p>
<code class="literal">jsonb_path_query_array('[1, 2, 3]', '$[*] ? (@ > 2)')</code>
→ <code class="returnvalue">[3]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>value</code></em> <code class="literal">>=</code> <em class="replaceable"><code>value</code></em>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Greater-than-or-equal-to comparison
</p>
<p>
<code class="literal">jsonb_path_query_array('[1, 2, 3]', '$[*] ? (@ >= 2)')</code>
→ <code class="returnvalue">[2, 3]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="literal">true</code>
→ <code class="returnvalue">boolean</code>
</p>
<p>
JSON constant <code class="literal">true</code>
</p>
<p>
<code class="literal">jsonb_path_query('[{"name": "John", "parent": false}, {"name": "Chris", "parent": true}]', '$[*] ? (@.parent == true)')</code>
→ <code class="returnvalue">{"name": "Chris", "parent": true}</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="literal">false</code>
→ <code class="returnvalue">boolean</code>
</p>
<p>
JSON constant <code class="literal">false</code>
</p>
<p>
<code class="literal">jsonb_path_query('[{"name": "John", "parent": false}, {"name": "Chris", "parent": true}]', '$[*] ? (@.parent == false)')</code>
→ <code class="returnvalue">{"name": "John", "parent": false}</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="literal">null</code>
→ <code class="returnvalue"><em class="replaceable"><code>value</code></em></code>
</p>
<p>
JSON constant <code class="literal">null</code> (note that, unlike in SQL,
comparison to <code class="literal">null</code> works normally)
</p>
<p>
<code class="literal">jsonb_path_query('[{"name": "Mary", "job": null}, {"name": "Michael", "job": "driver"}]', '$[*] ? (@.job == null) .name')</code>
→ <code class="returnvalue">"Mary"</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>boolean</code></em> <code class="literal">&&</code> <em class="replaceable"><code>boolean</code></em>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Boolean AND
</p>
<p>
<code class="literal">jsonb_path_query('[1, 3, 7]', '$[*] ? (@ > 1 && @ < 5)')</code>
→ <code class="returnvalue">3</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>boolean</code></em> <code class="literal">||</code> <em class="replaceable"><code>boolean</code></em>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Boolean OR
</p>
<p>
<code class="literal">jsonb_path_query('[1, 3, 7]', '$[*] ? (@ < 1 || @ > 5)')</code>
→ <code class="returnvalue">7</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="literal">!</code> <em class="replaceable"><code>boolean</code></em>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Boolean NOT
</p>
<p>
<code class="literal">jsonb_path_query('[1, 3, 7]', '$[*] ? (!(@ < 5))')</code>
→ <code class="returnvalue">7</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>boolean</code></em> <code class="literal">is unknown</code>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Tests whether a Boolean condition is <code class="literal">unknown</code>.
</p>
<p>
<code class="literal">jsonb_path_query('[-1, 2, 7, "foo"]', '$[*] ? ((@ > 0) is unknown)')</code>
→ <code class="returnvalue">"foo"</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>string</code></em> <code class="literal">like_regex</code> <em class="replaceable"><code>string</code></em> [<span class="optional"> <code class="literal">flag</code> <em class="replaceable"><code>string</code></em> </span>]
→ <code class="returnvalue">boolean</code>
</p>
<p>
Tests whether the first operand matches the regular expression
given by the second operand, optionally with modifications
described by a string of <code class="literal">flag</code> characters (see
<a class="xref" href="functions-json.html#JSONPATH-REGULAR-EXPRESSIONS" title="9.16.2.3. SQL/JSON Regular Expressions">Section 9.16.2.3</a>).
</p>
<p>
<code class="literal">jsonb_path_query_array('["abc", "abd", "aBdC", "abdacb", "babc"]', '$[*] ? (@ like_regex "^ab.*c")')</code>
→ <code class="returnvalue">["abc", "abdacb"]</code>
</p>
<p>
<code class="literal">jsonb_path_query_array('["abc", "abd", "aBdC", "abdacb", "babc"]', '$[*] ? (@ like_regex "^ab.*c" flag "i")')</code>
→ <code class="returnvalue">["abc", "aBdC", "abdacb"]</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<em class="replaceable"><code>string</code></em> <code class="literal">starts with</code> <em class="replaceable"><code>string</code></em>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Tests whether the second operand is an initial substring of the first
operand.
</p>
<p>
<code class="literal">jsonb_path_query('["John Smith", "Mary Stone", "Bob Johnson"]', '$[*] ? (@ starts with "John")')</code>
→ <code class="returnvalue">"John Smith"</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="literal">exists</code> <code class="literal">(</code> <em class="replaceable"><code>path_expression</code></em> <code class="literal">)</code>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Tests whether a path expression matches at least one SQL/JSON item.
Returns <code class="literal">unknown</code> if the path expression would result
in an error; the second example uses this to avoid a no-such-key error
in strict mode.
</p>
<p>
<code class="literal">jsonb_path_query('{"x": [1, 2], "y": [2, 4]}', 'strict $.* ? (exists (@ ? (@[*] > 2)))')</code>
→ <code class="returnvalue">[2, 4]</code>
</p>
<p>
<code class="literal">jsonb_path_query_array('{"value": 41}', 'strict $ ? (exists (@.name)) .name')</code>
→ <code class="returnvalue">[]</code>
</p></td></tr></tbody></table></div></div><br class="table-break" /></div><div class="sect3" id="JSONPATH-REGULAR-EXPRESSIONS"><div class="titlepage"><div><div><h4 class="title">9.16.2.3. SQL/JSON Regular Expressions <a href="#JSONPATH-REGULAR-EXPRESSIONS" class="id_link">#</a></h4></div></div></div><a id="id-1.5.8.22.9.24.2" class="indexterm"></a><p>
SQL/JSON path expressions allow matching text to a regular expression
with the <code class="literal">like_regex</code> filter. For example, the
following SQL/JSON path query would case-insensitively match all
strings in an array that start with an English vowel:
</p><pre class="programlisting">
$[*] ? (@ like_regex "^[aeiou]" flag "i")
</pre><p>
</p><p>
The optional <code class="literal">flag</code> string may include one or more of
the characters
<code class="literal">i</code> for case-insensitive match,
<code class="literal">m</code> to allow <code class="literal">^</code>
and <code class="literal">$</code> to match at newlines,
<code class="literal">s</code> to allow <code class="literal">.</code> to match a newline,
and <code class="literal">q</code> to quote the whole pattern (reducing the
behavior to a simple substring match).
</p><p>
The SQL/JSON standard borrows its definition for regular expressions
from the <code class="literal">LIKE_REGEX</code> operator, which in turn uses the
XQuery standard. PostgreSQL does not currently support the
<code class="literal">LIKE_REGEX</code> operator. Therefore,
the <code class="literal">like_regex</code> filter is implemented using the
POSIX regular expression engine described in
<a class="xref" href="functions-matching.html#FUNCTIONS-POSIX-REGEXP" title="9.7.3. POSIX Regular Expressions">Section 9.7.3</a>. This leads to various minor
discrepancies from standard SQL/JSON behavior, which are cataloged in
<a class="xref" href="functions-matching.html#POSIX-VS-XQUERY" title="9.7.3.8. Differences from SQL Standard and XQuery">Section 9.7.3.8</a>.
Note, however, that the flag-letter incompatibilities described there
do not apply to SQL/JSON, as it translates the XQuery flag letters to
match what the POSIX engine expects.
</p><p>
Keep in mind that the pattern argument of <code class="literal">like_regex</code>
is a JSON path string literal, written according to the rules given in
<a class="xref" href="datatype-json.html#DATATYPE-JSONPATH" title="8.14.7. jsonpath Type">Section 8.14.7</a>. This means in particular that any
backslashes you want to use in the regular expression must be doubled.
For example, to match string values of the root document that contain
only digits:
</p><pre class="programlisting">
$.* ? (@ like_regex "^\\d+$")
</pre><p>
</p></div></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="functions-xml.html" title="9.15. XML Functions">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="functions.html" title="Chapter 9. Functions and Operators">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="functions-sequence.html" title="9.17. Sequence Manipulation Functions">Next</a></td></tr><tr><td width="40%" align="left" valign="top">9.15. XML Functions </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 9.17. Sequence Manipulation Functions</td></tr></table></div></body></html>