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import itertools
from .. import widgets
from .core import Field
from .core import UnboundField
from wtforms.utils import unset_value
__all__ = ("FieldList",)
class FieldList(Field):
"""
Encapsulate an ordered list of multiple instances of the same field type,
keeping data as a list.
>>> authors = FieldList(StringField('Name', [validators.DataRequired()]))
:param unbound_field:
A partially-instantiated field definition, just like that would be
defined on a form directly.
:param min_entries:
if provided, always have at least this many entries on the field,
creating blank ones if the provided input does not specify a sufficient
amount.
:param max_entries:
accept no more than this many entries as input, even if more exist in
formdata.
:param separator:
A string which will be suffixed to this field's name to create the
prefix to enclosed list entries. The default is fine for most uses.
"""
widget = widgets.ListWidget()
def __init__(
self,
unbound_field,
label=None,
validators=None,
min_entries=0,
max_entries=None,
separator="-",
default=(),
**kwargs,
):
super().__init__(label, validators, default=default, **kwargs)
if self.filters:
raise TypeError(
"FieldList does not accept any filters. Instead, define"
" them on the enclosed field."
)
assert isinstance(
unbound_field, UnboundField
), "Field must be unbound, not a field class"
self.unbound_field = unbound_field
self.min_entries = min_entries
self.max_entries = max_entries
self.last_index = -1
self._prefix = kwargs.get("_prefix", "")
self._separator = separator
self._field_separator = unbound_field.kwargs.get("separator", "-")
def process(self, formdata, data=unset_value, extra_filters=None):
if extra_filters:
raise TypeError(
"FieldList does not accept any filters. Instead, define"
" them on the enclosed field."
)
self.entries = []
if data is unset_value or not data:
try:
data = self.default()
except TypeError:
data = self.default
self.object_data = data
if formdata:
indices = sorted(set(self._extract_indices(self.name, formdata)))
if self.max_entries:
indices = indices[: self.max_entries]
idata = iter(data)
for index in indices:
try:
obj_data = next(idata)
except StopIteration:
obj_data = unset_value
self._add_entry(formdata, obj_data, index=index)
else:
for obj_data in data:
self._add_entry(formdata, obj_data)
while len(self.entries) < self.min_entries:
self._add_entry(formdata)
def _extract_indices(self, prefix, formdata):
"""
Yield indices of any keys with given prefix.
formdata must be an object which will produce keys when iterated. For
example, if field 'foo' contains keys 'foo-0-bar', 'foo-1-baz', then
the numbers 0 and 1 will be yielded, but not necessarily in order.
"""
offset = len(prefix) + 1
for k in formdata:
if k.startswith(prefix):
k = k[offset:].split(self._field_separator, 1)[0]
if k.isdigit():
yield int(k)
def validate(self, form, extra_validators=()):
"""
Validate this FieldList.
Note that FieldList validation differs from normal field validation in
that FieldList validates all its enclosed fields first before running any
of its own validators.
"""
self.errors = []
# Run validators on all entries within
for subfield in self.entries:
subfield.validate(form)
self.errors.append(subfield.errors)
if not any(x for x in self.errors):
self.errors = []
chain = itertools.chain(self.validators, extra_validators)
self._run_validation_chain(form, chain)
return len(self.errors) == 0
def populate_obj(self, obj, name):
values = getattr(obj, name, None)
try:
ivalues = iter(values)
except TypeError:
ivalues = iter([])
candidates = itertools.chain(ivalues, itertools.repeat(None))
_fake = type("_fake", (object,), {})
output = []
for field, data in zip(self.entries, candidates):
fake_obj = _fake()
fake_obj.data = data
field.populate_obj(fake_obj, "data")
output.append(fake_obj.data)
setattr(obj, name, output)
def _add_entry(self, formdata=None, data=unset_value, index=None):
assert (
not self.max_entries or len(self.entries) < self.max_entries
), "You cannot have more than max_entries entries in this FieldList"
if index is None:
index = self.last_index + 1
self.last_index = index
name = f"{self.short_name}{self._separator}{index}"
id = f"{self.id}{self._separator}{index}"
field = self.unbound_field.bind(
form=None,
name=name,
prefix=self._prefix,
id=id,
_meta=self.meta,
translations=self._translations,
)
field.process(formdata, data)
self.entries.append(field)
return field
def append_entry(self, data=unset_value):
"""
Create a new entry with optional default data.
Entries added in this way will *not* receive formdata however, and can
only receive object data.
"""
return self._add_entry(data=data)
def pop_entry(self):
"""Removes the last entry from the list and returns it."""
entry = self.entries.pop()
self.last_index -= 1
return entry
def __iter__(self):
return iter(self.entries)
def __len__(self):
return len(self.entries)
def __getitem__(self, index):
return self.entries[index]
@property
def data(self):
return [f.data for f in self.entries]