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Your IP : 3.19.54.41
"""
Protocol objects representing different implementations of the same classes.
"""
# Copyright (C) 2020 The Psycopg Team
from typing import Any, Callable, Generator, Mapping
from typing import List, Optional, Sequence, Tuple, TypeVar, Union
from typing import TYPE_CHECKING
from typing_extensions import TypeAlias
from . import pq
from ._enums import PyFormat as PyFormat
from ._compat import Protocol, LiteralString
if TYPE_CHECKING:
from . import sql
from .rows import Row, RowMaker
from .pq.abc import PGresult
from .waiting import Wait, Ready
from .connection import BaseConnection
from ._adapters_map import AdaptersMap
NoneType: type = type(None)
# An object implementing the buffer protocol
Buffer: TypeAlias = Union[bytes, bytearray, memoryview]
Query: TypeAlias = Union[LiteralString, bytes, "sql.SQL", "sql.Composed"]
Params: TypeAlias = Union[Sequence[Any], Mapping[str, Any]]
ConnectionType = TypeVar("ConnectionType", bound="BaseConnection[Any]")
PipelineCommand: TypeAlias = Callable[[], None]
DumperKey: TypeAlias = Union[type, Tuple["DumperKey", ...]]
# Waiting protocol types
RV = TypeVar("RV")
PQGenConn: TypeAlias = Generator[Tuple[int, "Wait"], "Ready", RV]
"""Generator for processes where the connection file number can change.
This can happen in connection and reset, but not in normal querying.
"""
PQGen: TypeAlias = Generator["Wait", "Ready", RV]
"""Generator for processes where the connection file number won't change.
"""
class WaitFunc(Protocol):
"""
Wait on the connection which generated `PQgen` and return its final result.
"""
def __call__(
self, gen: PQGen[RV], fileno: int, timeout: Optional[float] = None
) -> RV:
...
# Adaptation types
DumpFunc: TypeAlias = Callable[[Any], Buffer]
LoadFunc: TypeAlias = Callable[[Buffer], Any]
class AdaptContext(Protocol):
"""
A context describing how types are adapted.
Example of `~AdaptContext` are `~psycopg.Connection`, `~psycopg.Cursor`,
`~psycopg.adapt.Transformer`, `~psycopg.adapt.AdaptersMap`.
Note that this is a `~typing.Protocol`, so objects implementing
`!AdaptContext` don't need to explicitly inherit from this class.
"""
@property
def adapters(self) -> "AdaptersMap":
"""The adapters configuration that this object uses."""
...
@property
def connection(self) -> Optional["BaseConnection[Any]"]:
"""The connection used by this object, if available.
:rtype: `~psycopg.Connection` or `~psycopg.AsyncConnection` or `!None`
"""
...
class Dumper(Protocol):
"""
Convert Python objects of type `!cls` to PostgreSQL representation.
"""
format: pq.Format
"""
The format that this class `dump()` method produces,
`~psycopg.pq.Format.TEXT` or `~psycopg.pq.Format.BINARY`.
This is a class attribute.
"""
oid: int
"""The oid to pass to the server, if known; 0 otherwise (class attribute)."""
def __init__(self, cls: type, context: Optional[AdaptContext] = None):
...
def dump(self, obj: Any) -> Buffer:
"""Convert the object `!obj` to PostgreSQL representation.
:param obj: the object to convert.
"""
...
def quote(self, obj: Any) -> Buffer:
"""Convert the object `!obj` to escaped representation.
:param obj: the object to convert.
"""
...
def get_key(self, obj: Any, format: PyFormat) -> DumperKey:
"""Return an alternative key to upgrade the dumper to represent `!obj`.
:param obj: The object to convert
:param format: The format to convert to
Normally the type of the object is all it takes to define how to dump
the object to the database. For instance, a Python `~datetime.date` can
be simply converted into a PostgreSQL :sql:`date`.
In a few cases, just the type is not enough. For example:
- A Python `~datetime.datetime` could be represented as a
:sql:`timestamptz` or a :sql:`timestamp`, according to whether it
specifies a `!tzinfo` or not.
- A Python int could be stored as several Postgres types: int2, int4,
int8, numeric. If a type too small is used, it may result in an
overflow. If a type too large is used, PostgreSQL may not want to
cast it to a smaller type.
- Python lists should be dumped according to the type they contain to
convert them to e.g. array of strings, array of ints (and which
size of int?...)
In these cases, a dumper can implement `!get_key()` and return a new
class, or sequence of classes, that can be used to identify the same
dumper again. If the mechanism is not needed, the method should return
the same `!cls` object passed in the constructor.
If a dumper implements `get_key()` it should also implement
`upgrade()`.
"""
...
def upgrade(self, obj: Any, format: PyFormat) -> "Dumper":
"""Return a new dumper to manage `!obj`.
:param obj: The object to convert
:param format: The format to convert to
Once `Transformer.get_dumper()` has been notified by `get_key()` that
this Dumper class cannot handle `!obj` itself, it will invoke
`!upgrade()`, which should return a new `Dumper` instance, which will
be reused for every objects for which `!get_key()` returns the same
result.
"""
...
class Loader(Protocol):
"""
Convert PostgreSQL values with type OID `!oid` to Python objects.
"""
format: pq.Format
"""
The format that this class `load()` method can convert,
`~psycopg.pq.Format.TEXT` or `~psycopg.pq.Format.BINARY`.
This is a class attribute.
"""
def __init__(self, oid: int, context: Optional[AdaptContext] = None):
...
def load(self, data: Buffer) -> Any:
"""
Convert the data returned by the database into a Python object.
:param data: the data to convert.
"""
...
class Transformer(Protocol):
types: Optional[Tuple[int, ...]]
formats: Optional[List[pq.Format]]
def __init__(self, context: Optional[AdaptContext] = None):
...
@classmethod
def from_context(cls, context: Optional[AdaptContext]) -> "Transformer":
...
@property
def connection(self) -> Optional["BaseConnection[Any]"]:
...
@property
def encoding(self) -> str:
...
@property
def adapters(self) -> "AdaptersMap":
...
@property
def pgresult(self) -> Optional["PGresult"]:
...
def set_pgresult(
self,
result: Optional["PGresult"],
*,
set_loaders: bool = True,
format: Optional[pq.Format] = None
) -> None:
...
def set_dumper_types(self, types: Sequence[int], format: pq.Format) -> None:
...
def set_loader_types(self, types: Sequence[int], format: pq.Format) -> None:
...
def dump_sequence(
self, params: Sequence[Any], formats: Sequence[PyFormat]
) -> Sequence[Optional[Buffer]]:
...
def as_literal(self, obj: Any) -> bytes:
...
def get_dumper(self, obj: Any, format: PyFormat) -> Dumper:
...
def load_rows(self, row0: int, row1: int, make_row: "RowMaker[Row]") -> List["Row"]:
...
def load_row(self, row: int, make_row: "RowMaker[Row]") -> Optional["Row"]:
...
def load_sequence(self, record: Sequence[Optional[Buffer]]) -> Tuple[Any, ...]:
...
def get_loader(self, oid: int, format: pq.Format) -> Loader:
...