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Helper functions for creating Form classes from Django models
and database field objects.
from __future__ import absolute_import
from django.core.exceptions import ValidationError, NON_FIELD_ERRORS, FieldError
from django.core.validators import EMPTY_VALUES
from django.forms.fields import Field, ChoiceField
from django.forms.forms import BaseForm, get_declared_fields
from django.forms.formsets import BaseFormSet, formset_factory
from django.forms.util import ErrorList
from django.forms.widgets import (SelectMultiple, HiddenInput,
MultipleHiddenInput, media_property)
from django.utils.encoding import smart_unicode, force_unicode
from django.utils.datastructures import SortedDict
from django.utils.text import get_text_list, capfirst
from django.utils.translation import ugettext_lazy as _, ugettext
__all__ = (
'ModelForm', 'BaseModelForm', 'model_to_dict', 'fields_for_model',
'save_instance', 'ModelChoiceField', 'ModelMultipleChoiceField',
def construct_instance(form, instance, fields=None, exclude=None):
Constructs and returns a model instance from the bound ``form``'s
``cleaned_data``, but does not save the returned instance to the
from django.db import models
opts = instance._meta
cleaned_data = form.cleaned_data
file_field_list = []
for f in opts.fields:
if not f.editable or isinstance(f, models.AutoField) \
or not in cleaned_data:
if fields is not None and not in fields:
if exclude and in exclude:
# Defer saving file-type fields until after the other fields, so a
# callable upload_to can use the values from other fields.
if isinstance(f, models.FileField):
f.save_form_data(instance, cleaned_data[])
for f in file_field_list:
f.save_form_data(instance, cleaned_data[])
return instance
def save_instance(form, instance, fields=None, fail_message='saved',
commit=True, exclude=None, construct=True):
Saves bound Form ``form``'s cleaned_data into model instance ``instance``.
If commit=True, then the changes to ``instance`` will be saved to the
database. Returns ``instance``.
If construct=False, assume ``instance`` has already been constructed and
just needs to be saved.
if construct:
instance = construct_instance(form, instance, fields, exclude)
opts = instance._meta
if form.errors:
raise ValueError("The %s could not be %s because the data didn't"
" validate." % (opts.object_name, fail_message))
# Wrap up the saving of m2m data as a function.
def save_m2m():
cleaned_data = form.cleaned_data
for f in opts.many_to_many:
if fields and not in fields:
if in cleaned_data:
f.save_form_data(instance, cleaned_data[])
if commit:
# If we are committing, save the instance and the m2m data immediately.
# We're not committing. Add a method to the form to allow deferred
# saving of m2m data.
form.save_m2m = save_m2m
return instance
# ModelForms #################################################################
def model_to_dict(instance, fields=None, exclude=None):
Returns a dict containing the data in ``instance`` suitable for passing as
a Form's ``initial`` keyword argument.
``fields`` is an optional list of field names. If provided, only the named
fields will be included in the returned dict.
``exclude`` is an optional list of field names. If provided, the named
fields will be excluded from the returned dict, even if they are listed in
the ``fields`` argument.
# avoid a circular import
from django.db.models.fields.related import ManyToManyField
opts = instance._meta
data = {}
for f in opts.fields + opts.many_to_many:
if not f.editable:
if fields and not in fields:
if exclude and in exclude:
if isinstance(f, ManyToManyField):
# If the object doesn't have a primary key yet, just use an empty
# list for its m2m fields. Calling f.value_from_object will raise
# an exception.
if is None:
data[] = []
# MultipleChoiceWidget needs a list of pks, not object instances.
data[] = [ for obj in f.value_from_object(instance)]
data[] = f.value_from_object(instance)
return data
def fields_for_model(model, fields=None, exclude=None, widgets=None, formfield_callback=None):
Returns a ``SortedDict`` containing form fields for the given model.
``fields`` is an optional list of field names. If provided, only the named
fields will be included in the returned fields.
``exclude`` is an optional list of field names. If provided, the named
fields will be excluded from the returned fields, even if they are listed
in the ``fields`` argument.
field_list = []
ignored = []
opts = model._meta
for f in sorted(opts.fields + opts.many_to_many):
if not f.editable:
if fields is not None and not in fields:
if exclude and in exclude:
if widgets and in widgets:
kwargs = {'widget': widgets[]}
kwargs = {}
if formfield_callback is None:
formfield = f.formfield(**kwargs)
elif not callable(formfield_callback):
raise TypeError('formfield_callback must be a function or callable')
formfield = formfield_callback(f, **kwargs)
if formfield:
field_list.append((, formfield))
field_dict = SortedDict(field_list)
if fields:
field_dict = SortedDict(
[(f, field_dict.get(f)) for f in fields
if ((not exclude) or (exclude and f not in exclude)) and (f not in ignored)]
return field_dict
class ModelFormOptions(object):
def __init__(self, options=None):
self.model = getattr(options, 'model', None)
self.fields = getattr(options, 'fields', None)
self.exclude = getattr(options, 'exclude', None)
self.widgets = getattr(options, 'widgets', None)
class ModelFormMetaclass(type):
def __new__(cls, name, bases, attrs):
formfield_callback = attrs.pop('formfield_callback', None)
parents = [b for b in bases if issubclass(b, ModelForm)]
except NameError:
# We are defining ModelForm itself.
parents = None
declared_fields = get_declared_fields(bases, attrs, False)
new_class = super(ModelFormMetaclass, cls).__new__(cls, name, bases,
if not parents:
return new_class
if 'media' not in attrs: = media_property(new_class)
opts = new_class._meta = ModelFormOptions(getattr(new_class, 'Meta', None))
if opts.model:
# If a model is defined, extract form fields from it.
fields = fields_for_model(opts.model, opts.fields,
opts.exclude, opts.widgets, formfield_callback)
# make sure opts.fields doesn't specify an invalid field
none_model_fields = [k for k, v in fields.iteritems() if not v]
missing_fields = set(none_model_fields) - \
if missing_fields:
message = 'Unknown field(s) (%s) specified for %s'
message = message % (', '.join(missing_fields),
raise FieldError(message)
# Override default model fields with any custom declared ones
# (plus, include all the other declared fields).
fields = declared_fields
new_class.declared_fields = declared_fields
new_class.base_fields = fields
return new_class
class BaseModelForm(BaseForm):
def __init__(self, data=None, files=None, auto_id='id_%s', prefix=None,
initial=None, error_class=ErrorList, label_suffix=':',
empty_permitted=False, instance=None):
opts = self._meta
if instance is None:
if opts.model is None:
raise ValueError('ModelForm has no model class specified.')
# if we didn't get an instance, instantiate a new one
self.instance = opts.model()
object_data = {}
self.instance = instance
object_data = model_to_dict(instance, opts.fields, opts.exclude)
# if initial was provided, it should override the values from instance
if initial is not None:
# self._validate_unique will be set to True by BaseModelForm.clean().
# It is False by default so overriding self.clean() and failing to call
# super will stop validate_unique from being called.
self._validate_unique = False
super(BaseModelForm, self).__init__(data, files, auto_id, prefix, object_data,
error_class, label_suffix, empty_permitted)
def _update_errors(self, message_dict):
for k, v in message_dict.items():
self._errors.setdefault(k, self.error_class()).extend(v)
# Remove the data from the cleaned_data dict since it was invalid
if k in self.cleaned_data:
del self.cleaned_data[k]
if NON_FIELD_ERRORS in message_dict:
messages = message_dict[NON_FIELD_ERRORS]
self._errors.setdefault(NON_FIELD_ERRORS, self.error_class()).extend(messages)
def _get_validation_exclusions(self):
For backwards-compatibility, several types of fields need to be
excluded from model validation. See the following tickets for
details: #12507, #12521, #12553
exclude = []
# Build up a list of fields that should be excluded from model field
# validation and unique checks.
for f in self.instance._meta.fields:
field =
# Exclude fields that aren't on the form. The developer may be
# adding these values to the model after form validation.
if field not in self.fields:
# Don't perform model validation on fields that were defined
# manually on the form and excluded via the ModelForm's Meta
# class. See #12901.
elif self._meta.fields and field not in self._meta.fields:
elif self._meta.exclude and field in self._meta.exclude:
# Exclude fields that failed form validation. There's no need for
# the model fields to validate them as well.
elif field in self._errors.keys():
# Exclude empty fields that are not required by the form, if the
# underlying model field is required. This keeps the model field
# from raising a required error. Note: don't exclude the field from
# validation if the model field allows blanks. If it does, the blank
# value may be included in a unique check, so cannot be excluded
# from validation.
form_field = self.fields[field]
field_value = self.cleaned_data.get(field, None)
if not f.blank and not form_field.required and field_value in EMPTY_VALUES:
return exclude
def clean(self):
self._validate_unique = True
return self.cleaned_data
def _post_clean(self):
opts = self._meta
# Update the model instance with self.cleaned_data.
self.instance = construct_instance(self, self.instance, opts.fields, opts.exclude)
exclude = self._get_validation_exclusions()
# Foreign Keys being used to represent inline relationships
# are excluded from basic field value validation. This is for two
# reasons: firstly, the value may not be supplied (#12507; the
# case of providing new values to the admin); secondly the
# object being referred to may not yet fully exist (#12749).
# However, these fields *must* be included in uniqueness checks,
# so this can't be part of _get_validation_exclusions().
for f_name, field in self.fields.items():
if isinstance(field, InlineForeignKeyField):
# Clean the model instance's fields.
except ValidationError, e:
# Call the model instance's clean method.
except ValidationError, e:
self._update_errors({NON_FIELD_ERRORS: e.messages})
# Validate uniqueness if needed.
if self._validate_unique:
def validate_unique(self):
Calls the instance's validate_unique() method and updates the form's
validation errors if any were raised.
exclude = self._get_validation_exclusions()
except ValidationError, e:
def save(self, commit=True):
Saves this ``form``'s cleaned_data into model instance
If commit=True, then the changes to ``instance`` will be saved to the
database. Returns ``instance``.
if is None:
fail_message = 'created'
fail_message = 'changed'
return save_instance(self, self.instance, self._meta.fields,
fail_message, commit, construct=False)
save.alters_data = True
class ModelForm(BaseModelForm):
__metaclass__ = ModelFormMetaclass
def modelform_factory(model, form=ModelForm, fields=None, exclude=None,
formfield_callback=None, widgets=None):
# Create the inner Meta class. FIXME: ideally, we should be able to
# construct a ModelForm without creating and passing in a temporary
# inner class.
# Build up a list of attributes that the Meta object will have.
attrs = {'model': model}
if fields is not None:
attrs['fields'] = fields
if exclude is not None:
attrs['exclude'] = exclude
if widgets is not None:
attrs['widgets'] = widgets
# If parent form class already has an inner Meta, the Meta we're
# creating needs to inherit from the parent's inner meta.
parent = (object,)
if hasattr(form, 'Meta'):
parent = (form.Meta, object)
Meta = type('Meta', parent, attrs)
# Give this new form class a reasonable name.
class_name = model.__name__ + 'Form'
# Class attributes for the new form class.
form_class_attrs = {
'Meta': Meta,
'formfield_callback': formfield_callback
form_metaclass = ModelFormMetaclass
if issubclass(form, BaseModelForm) and hasattr(form, '__metaclass__'):
form_metaclass = form.__metaclass__
return form_metaclass(class_name, (form,), form_class_attrs)
# ModelFormSets ##############################################################
class BaseModelFormSet(BaseFormSet):
A ``FormSet`` for editing a queryset and/or adding new objects to it.
model = None
def __init__(self, data=None, files=None, auto_id='id_%s', prefix=None,
queryset=None, **kwargs):
self.queryset = queryset
self.initial_extra = kwargs.pop('initial', None)
defaults = {'data': data, 'files': files, 'auto_id': auto_id, 'prefix': prefix}
super(BaseModelFormSet, self).__init__(**defaults)
def initial_form_count(self):
"""Returns the number of forms that are required in this FormSet."""
if not ( or self.files):
return len(self.get_queryset())
return super(BaseModelFormSet, self).initial_form_count()
def _existing_object(self, pk):
if not hasattr(self, '_object_dict'):
self._object_dict = dict([(, o) for o in self.get_queryset()])
return self._object_dict.get(pk)
def _construct_form(self, i, **kwargs):
if self.is_bound and i < self.initial_form_count():
# Import goes here instead of module-level because importing
# django.db has side effects.
from django.db import connections
pk_key = "%s-%s" % (self.add_prefix(i),
pk =[pk_key]
pk_field =
pk = pk_field.get_db_prep_lookup('exact', pk,
if isinstance(pk, list):
pk = pk[0]
kwargs['instance'] = self._existing_object(pk)
if i < self.initial_form_count() and not kwargs.get('instance'):
kwargs['instance'] = self.get_queryset()[i]
if i >= self.initial_form_count() and self.initial_extra:
# Set initial values for extra forms
kwargs['initial'] = self.initial_extra[i-self.initial_form_count()]
except IndexError:
return super(BaseModelFormSet, self)._construct_form(i, **kwargs)
def get_queryset(self):
if not hasattr(self, '_queryset'):
if self.queryset is not None:
qs = self.queryset
qs = self.model._default_manager.get_query_set()
# If the queryset isn't already ordered we need to add an
# artificial ordering here to make sure that all formsets
# constructed from this queryset have the same form order.
if not qs.ordered:
qs = qs.order_by(
# Removed queryset limiting here. As per discussion re: #13023
# on django-dev, max_num should not prevent existing
# related objects/inlines from being displayed.
self._queryset = qs
return self._queryset
def save_new(self, form, commit=True):
"""Saves and returns a new model instance for the given form."""
def save_existing(self, form, instance, commit=True):
"""Saves and returns an existing model instance for the given form."""
def save(self, commit=True):
"""Saves model instances for every form, adding and changing instances
as necessary, and returns the list of instances.
if not commit:
self.saved_forms = []
def save_m2m():
for form in self.saved_forms:
self.save_m2m = save_m2m
return self.save_existing_objects(commit) + self.save_new_objects(commit)
def clean(self):
def validate_unique(self):
# Collect unique_checks and date_checks to run from all the forms.
all_unique_checks = set()
all_date_checks = set()
for form in self.forms:
if not hasattr(form, 'cleaned_data'):
exclude = form._get_validation_exclusions()
unique_checks, date_checks = form.instance._get_unique_checks(exclude=exclude)
all_unique_checks = all_unique_checks.union(set(unique_checks))
all_date_checks = all_date_checks.union(set(date_checks))
errors = []
# Do each of the unique checks (unique and unique_together)
for uclass, unique_check in all_unique_checks:
seen_data = set()
for form in self.forms:
# if the form doesn't have cleaned_data then we ignore it,
# it's already invalid
if not hasattr(form, "cleaned_data"):
# get data for each field of each of unique_check
row_data = tuple([form.cleaned_data[field] for field in unique_check if field in form.cleaned_data])
if row_data and not None in row_data:
# if we've aready seen it then we have a uniqueness failure
if row_data in seen_data:
# poke error messages into the right places and mark
# the form as invalid
form._errors[NON_FIELD_ERRORS] = self.error_class([self.get_form_error()])
del form.cleaned_data
# mark the data as seen
# iterate over each of the date checks now
for date_check in all_date_checks:
seen_data = set()
uclass, lookup, field, unique_for = date_check
for form in self.forms:
# if the form doesn't have cleaned_data then we ignore it,
# it's already invalid
if not hasattr(self, 'cleaned_data'):
# see if we have data for both fields
if (form.cleaned_data and form.cleaned_data[field] is not None
and form.cleaned_data[unique_for] is not None):
# if it's a date lookup we need to get the data for all the fields
if lookup == 'date':
date = form.cleaned_data[unique_for]
date_data = (date.year, date.month,
# otherwise it's just the attribute on the date/datetime
# object
date_data = (getattr(form.cleaned_data[unique_for], lookup),)
data = (form.cleaned_data[field],) + date_data
# if we've aready seen it then we have a uniqueness failure
if data in seen_data:
# poke error messages into the right places and mark
# the form as invalid
form._errors[NON_FIELD_ERRORS] = self.error_class([self.get_form_error()])
del form.cleaned_data
if errors:
raise ValidationError(errors)
def get_unique_error_message(self, unique_check):
if len(unique_check) == 1:
return ugettext("Please correct the duplicate data for %(field)s.") % {
"field": unique_check[0],
return ugettext("Please correct the duplicate data for %(field)s, "
"which must be unique.") % {
"field": get_text_list(unique_check, unicode(_("and"))),
def get_date_error_message(self, date_check):
return ugettext("Please correct the duplicate data for %(field_name)s "
"which must be unique for the %(lookup)s in %(date_field)s.") % {
'field_name': date_check[2],
'date_field': date_check[3],
'lookup': unicode(date_check[1]),
def get_form_error(self):
return ugettext("Please correct the duplicate values below.")
def save_existing_objects(self, commit=True):
self.changed_objects = []
self.deleted_objects = []
if not self.initial_forms:
return []
saved_instances = []
for form in self.initial_forms:
pk_name =
raw_pk_value = form._raw_value(pk_name)
# clean() for different types of PK fields can sometimes return
# the model instance, and sometimes the PK. Handle either.
pk_value = form.fields[pk_name].clean(raw_pk_value)
pk_value = getattr(pk_value, 'pk', pk_value)
obj = self._existing_object(pk_value)
if self.can_delete and self._should_delete_form(form):
if form.has_changed():
self.changed_objects.append((obj, form.changed_data))
saved_instances.append(self.save_existing(form, obj, commit=commit))
if not commit:
return saved_instances
def save_new_objects(self, commit=True):
self.new_objects = []
for form in self.extra_forms:
if not form.has_changed():
# If someone has marked an add form for deletion, don't save the
# object.
if self.can_delete and self._should_delete_form(form):
self.new_objects.append(self.save_new(form, commit=commit))
if not commit:
return self.new_objects
def add_fields(self, form, index):
"""Add a hidden field for the object's primary key."""
from django.db.models import AutoField, OneToOneField, ForeignKey
self._pk_field = pk =
# If a pk isn't editable, then it won't be on the form, so we need to
# add it here so we can tell which object is which when we get the
# data back. Generally, pk.editable should be false, but for some
# reason, auto_created pk fields and AutoField's editable attribute is
# True, so check for that as well.
def pk_is_not_editable(pk):
return ((not pk.editable) or (pk.auto_created or isinstance(pk, AutoField))
or (pk.rel and pk.rel.parent_link and pk_is_not_editable(
if pk_is_not_editable(pk) or not in form.fields:
if form.is_bound:
pk_value =
if index is not None:
pk_value = self.get_queryset()[index].pk
pk_value = None
except IndexError:
pk_value = None
if isinstance(pk, OneToOneField) or isinstance(pk, ForeignKey):
qs =
qs = self.model._default_manager.get_query_set()
qs = qs.using(form.instance._state.db)
form.fields[] = ModelChoiceField(qs, initial=pk_value, required=False, widget=HiddenInput)
super(BaseModelFormSet, self).add_fields(form, index)
def modelformset_factory(model, form=ModelForm, formfield_callback=None,
extra=1, can_delete=False, can_order=False,
max_num=None, fields=None, exclude=None):
Returns a FormSet class for the given Django model class.
form = modelform_factory(model, form=form, fields=fields, exclude=exclude,
FormSet = formset_factory(form, formset, extra=extra, max_num=max_num,
can_order=can_order, can_delete=can_delete)
FormSet.model = model
return FormSet
# InlineFormSets #############################################################
class BaseInlineFormSet(BaseModelFormSet):
"""A formset for child objects related to a parent."""
def __init__(self, data=None, files=None, instance=None,
save_as_new=False, prefix=None, queryset=None, **kwargs):
from django.db.models.fields.related import RelatedObject
if instance is None:
self.instance =
self.instance = instance
self.save_as_new = save_as_new
# is there a better way to get the object descriptor?
self.rel_name = RelatedObject(, self.model,
if queryset is None:
queryset = self.model._default_manager
qs = queryset.filter(**{ self.instance})
super(BaseInlineFormSet, self).__init__(data, files, prefix=prefix,
queryset=qs, **kwargs)
def initial_form_count(self):
if self.save_as_new:
return 0
return super(BaseInlineFormSet, self).initial_form_count()
def _construct_form(self, i, **kwargs):
form = super(BaseInlineFormSet, self)._construct_form(i, **kwargs)
if self.save_as_new:
# Remove the primary key from the form's data, we are only
# creating new instances[form.add_prefix(] = None
# Remove the foreign key from the form's data[form.add_prefix(] = None
# Set the fk value here so that the form can do it's validation.
return form
def get_default_prefix(cls):
from django.db.models.fields.related import RelatedObject
return RelatedObject(, cls.model,'+','')
def save_new(self, form, commit=True):
# Use commit=False so we can assign the parent key afterwards, then
# save the object.
obj =
pk_value = getattr(self.instance,
setattr(obj,, getattr(pk_value, 'pk', pk_value))
if commit:
# form.save_m2m() can be called via the formset later on if commit=False
if commit and hasattr(form, 'save_m2m'):
return obj
def add_fields(self, form, index):
super(BaseInlineFormSet, self).add_fields(form, index)
if self._pk_field ==
name =
kwargs = {'pk_field': True}
# The foreign key field might not be on the form, so we poke at the
# Model field to get the label, since we need that for error messages.
name =
kwargs = {
'label': getattr(form.fields.get(name), 'label', capfirst(
if !=
kwargs['to_field'] =
form.fields[name] = InlineForeignKeyField(self.instance, **kwargs)
# Add the generated field to form._meta.fields if it's defined to make
# sure validation isn't skipped on that field.
if form._meta.fields:
if isinstance(form._meta.fields, tuple):
form._meta.fields = list(form._meta.fields)
def get_unique_error_message(self, unique_check):
unique_check = [field for field in unique_check if field !=]
return super(BaseInlineFormSet, self).get_unique_error_message(unique_check)
def _get_foreign_key(parent_model, model, fk_name=None, can_fail=False):
Finds and returns the ForeignKey from model to parent if there is one
(returns None if can_fail is True and no such field exists). If fk_name is
provided, assume it is the name of the ForeignKey field. Unles can_fail is
True, an exception is raised if there is no ForeignKey from model to
# avoid circular import
from django.db.models import ForeignKey
opts = model._meta
if fk_name:
fks_to_parent = [f for f in opts.fields if == fk_name]
if len(fks_to_parent) == 1:
fk = fks_to_parent[0]
if not isinstance(fk, ForeignKey) or \
( != parent_model and not in parent_model._meta.get_parent_list()):
raise Exception("fk_name '%s' is not a ForeignKey to %s" % (fk_name, parent_model))
elif len(fks_to_parent) == 0:
raise Exception("%s has no field named '%s'" % (model, fk_name))
# Try to discover what the ForeignKey from model to parent_model is
fks_to_parent = [
f for f in opts.fields
if isinstance(f, ForeignKey)
and ( == parent_model
or in parent_model._meta.get_parent_list())
if len(fks_to_parent) == 1:
fk = fks_to_parent[0]
elif len(fks_to_parent) == 0:
if can_fail:
raise Exception("%s has no ForeignKey to %s" % (model, parent_model))
raise Exception("%s has more than 1 ForeignKey to %s" % (model, parent_model))
return fk
def inlineformset_factory(parent_model, model, form=ModelForm,
formset=BaseInlineFormSet, fk_name=None,
fields=None, exclude=None,
extra=3, can_order=False, can_delete=True, max_num=None,
Returns an ``InlineFormSet`` for the given kwargs.
You must provide ``fk_name`` if ``model`` has more than one ``ForeignKey``
to ``parent_model``.
fk = _get_foreign_key(parent_model, model, fk_name=fk_name)
# enforce a max_num=1 when the foreign key to the parent model is unique.
if fk.unique:
max_num = 1
kwargs = {
'form': form,
'formfield_callback': formfield_callback,
'formset': formset,
'extra': extra,
'can_delete': can_delete,
'can_order': can_order,
'fields': fields,
'exclude': exclude,
'max_num': max_num,
FormSet = modelformset_factory(model, **kwargs) = fk
return FormSet
# Fields #####################################################################
class InlineForeignKeyHiddenInput(HiddenInput):
def _has_changed(self, initial, data):
return False
class InlineForeignKeyField(Field):
A basic integer field that deals with validating the given value to a
given parent instance in an inline.
default_error_messages = {
'invalid_choice': _(u'The inline foreign key did not match the parent instance primary key.'),
def __init__(self, parent_instance, *args, **kwargs):
self.parent_instance = parent_instance
self.pk_field = kwargs.pop("pk_field", False)
self.to_field = kwargs.pop("to_field", None)
if self.parent_instance is not None:
if self.to_field:
kwargs["initial"] = getattr(self.parent_instance, self.to_field)
kwargs["initial"] =
kwargs["required"] = False
kwargs["widget"] = InlineForeignKeyHiddenInput
super(InlineForeignKeyField, self).__init__(*args, **kwargs)
def clean(self, value):
if value in EMPTY_VALUES:
if self.pk_field:
return None
# if there is no value act as we did before.
return self.parent_instance
# ensure the we compare the values as equal types.
if self.to_field:
orig = getattr(self.parent_instance, self.to_field)
orig =
if force_unicode(value) != force_unicode(orig):
raise ValidationError(self.error_messages['invalid_choice'])
return self.parent_instance
class ModelChoiceIterator(object):
def __init__(self, field):
self.field = field
self.queryset = field.queryset
def __iter__(self):
if self.field.empty_label is not None:
yield (u"", self.field.empty_label)
if self.field.cache_choices:
if self.field.choice_cache is None:
self.field.choice_cache = [
self.choice(obj) for obj in self.queryset.all()
for choice in self.field.choice_cache:
yield choice
for obj in self.queryset.all():
yield self.choice(obj)
def __len__(self):
return len(self.queryset)
def choice(self, obj):
return (self.field.prepare_value(obj), self.field.label_from_instance(obj))
class ModelChoiceField(ChoiceField):
"""A ChoiceField whose choices are a model QuerySet."""
# This class is a subclass of ChoiceField for purity, but it doesn't
# actually use any of ChoiceField's implementation.
default_error_messages = {
'invalid_choice': _(u'Select a valid choice. That choice is not one of'
u' the available choices.'),
def __init__(self, queryset, empty_label=u"---------", cache_choices=False,
required=True, widget=None, label=None, initial=None,
help_text=None, to_field_name=None, *args, **kwargs):
if required and (initial is not None):
self.empty_label = None
self.empty_label = empty_label
self.cache_choices = cache_choices
# Call Field instead of ChoiceField __init__() because we don't need
# ChoiceField.__init__().
Field.__init__(self, required, widget, label, initial, help_text,
*args, **kwargs)
self.queryset = queryset
self.choice_cache = None
self.to_field_name = to_field_name
def __deepcopy__(self, memo):
result = super(ChoiceField, self).__deepcopy__(memo)
# Need to force a new ModelChoiceIterator to be created, bug #11183
result.queryset = result.queryset
return result
def _get_queryset(self):
return self._queryset
def _set_queryset(self, queryset):
self._queryset = queryset
self.widget.choices = self.choices
queryset = property(_get_queryset, _set_queryset)
# this method will be used to create object labels by the QuerySetIterator.
# Override it to customize the label.
def label_from_instance(self, obj):
This method is used to convert objects into strings; it's used to
generate the labels for the choices presented by this object. Subclasses
can override this method to customize the display of the choices.
return smart_unicode(obj)
def _get_choices(self):
# If self._choices is set, then somebody must have manually set
# the property self.choices. In this case, just return self._choices.
if hasattr(self, '_choices'):
return self._choices
# Otherwise, execute the QuerySet in self.queryset to determine the
# choices dynamically. Return a fresh ModelChoiceIterator that has not been
# consumed. Note that we're instantiating a new ModelChoiceIterator *each*
# time _get_choices() is called (and, thus, each time self.choices is
# accessed) so that we can ensure the QuerySet has not been consumed. This
# construct might look complicated but it allows for lazy evaluation of
# the queryset.
return ModelChoiceIterator(self)
choices = property(_get_choices, ChoiceField._set_choices)
def prepare_value(self, value):
if hasattr(value, '_meta'):
if self.to_field_name:
return value.serializable_value(self.to_field_name)
return super(ModelChoiceField, self).prepare_value(value)
def to_python(self, value):
if value in EMPTY_VALUES:
return None
key = self.to_field_name or 'pk'
value = self.queryset.get(**{key: value})
except (ValueError, self.queryset.model.DoesNotExist):
raise ValidationError(self.error_messages['invalid_choice'])
return value
def validate(self, value):
return Field.validate(self, value)
class ModelMultipleChoiceField(ModelChoiceField):
"""A MultipleChoiceField whose choices are a model QuerySet."""
widget = SelectMultiple
hidden_widget = MultipleHiddenInput
default_error_messages = {
'list': _(u'Enter a list of values.'),
'invalid_choice': _(u'Select a valid choice. %s is not one of the'
u' available choices.'),
'invalid_pk_value': _(u'"%s" is not a valid value for a primary key.')
def __init__(self, queryset, cache_choices=False, required=True,
widget=None, label=None, initial=None,
help_text=None, *args, **kwargs):
super(ModelMultipleChoiceField, self).__init__(queryset, None,
cache_choices, required, widget, label, initial, help_text,
*args, **kwargs)
def clean(self, value):
if self.required and not value:
raise ValidationError(self.error_messages['required'])
elif not self.required and not value:
return []
if not isinstance(value, (list, tuple)):
raise ValidationError(self.error_messages['list'])
key = self.to_field_name or 'pk'
for pk in value:
self.queryset.filter(**{key: pk})
except ValueError:
raise ValidationError(self.error_messages['invalid_pk_value'] % pk)
qs = self.queryset.filter(**{'%s__in' % key: value})
pks = set([force_unicode(getattr(o, key)) for o in qs])
for val in value:
if force_unicode(val) not in pks:
raise ValidationError(self.error_messages['invalid_choice'] % val)
# Since this overrides the inherited ModelChoiceField.clean
# we run custom validators here
return qs
def prepare_value(self, value):
if hasattr(value, '__iter__'):
return [super(ModelMultipleChoiceField, self).prepare_value(v) for v in value]
return super(ModelMultipleChoiceField, self).prepare_value(value)
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