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Helper functions for creating Form classes from Django models
and database field objects.
from collections import OrderedDict
from itertools import chain
from django.core.exceptions import (
NON_FIELD_ERRORS, FieldError, ImproperlyConfigured, ValidationError,
from django.forms.fields import ChoiceField, Field
from django.forms.forms import BaseForm, DeclarativeFieldsMetaclass
from django.forms.formsets import BaseFormSet, formset_factory
from django.forms.utils import ErrorList
from django.forms.widgets import (
HiddenInput, MultipleHiddenInput, SelectMultiple,
from django.utils.text import capfirst, get_text_list
from django.utils.translation import gettext, gettext_lazy as _
__all__ = (
'ModelForm', 'BaseModelForm', 'model_to_dict', 'fields_for_model',
'ModelChoiceField', 'ModelMultipleChoiceField', 'ALL_FIELDS',
'BaseModelFormSet', 'modelformset_factory', 'BaseInlineFormSet',
'inlineformset_factory', 'modelform_factory',
ALL_FIELDS = '__all__'
def construct_instance(form, instance, fields=None, exclude=None):
Construct and return a model instance from the bound ``form``'s
``cleaned_data``, but do not save the returned instance to the database.
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:
# Leave defaults for fields that aren't in POST data, except for
# checkbox inputs because they don't appear in POST data if not checked.
if (f.has_default() and
form[].field.widget.value_omitted_from_data(, form.files, form.add_prefix(
# 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
# ModelForms #################################################################
def model_to_dict(instance, fields=None, exclude=None):
Return 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, return only the
``exclude`` is an optional list of field names. If provided, exclude the
named from the returned dict, even if they are listed in the ``fields``
opts = instance._meta
data = {}
for f in chain(opts.concrete_fields, opts.private_fields, opts.many_to_many):
if not getattr(f, 'editable', False):
if fields and not in fields:
if exclude and in exclude:
data[] = f.value_from_object(instance)
return data
def fields_for_model(model, fields=None, exclude=None, widgets=None,
formfield_callback=None, localized_fields=None,
labels=None, help_texts=None, error_messages=None,
Return an ``OrderedDict`` containing form fields for the given model.
``fields`` is an optional list of field names. If provided, return only the
named fields.
``exclude`` is an optional list of field names. If provided, exclude the
named fields from the returned fields, even if they are listed in the
``fields`` argument.
``widgets`` is a dictionary of model field names mapped to a widget.
``formfield_callback`` is a callable that takes a model field and returns
a form field.
``localized_fields`` is a list of names of fields which should be localized.
``labels`` is a dictionary of model field names mapped to a label.
``help_texts`` is a dictionary of model field names mapped to a help text.
``error_messages`` is a dictionary of model field names mapped to a
dictionary of error messages.
``field_classes`` is a dictionary of model field names mapped to a form
field class.
field_list = []
ignored = []
opts = model._meta
# Avoid circular import
from django.db.models.fields import Field as ModelField
sortable_private_fields = [f for f in opts.private_fields if isinstance(f, ModelField)]
for f in sorted(chain(opts.concrete_fields, sortable_private_fields, opts.many_to_many)):
if not getattr(f, 'editable', False):
if (fields is not None and in fields and
(exclude is None or not in exclude)):
raise FieldError(
"'%s' cannot be specified for %s model form as it is a non-editable field" % (, model.__name__)
if fields is not None and not in fields:
if exclude and in exclude:
kwargs = {}
if widgets and in widgets:
kwargs['widget'] = widgets[]
if localized_fields == ALL_FIELDS or (localized_fields and in localized_fields):
kwargs['localize'] = True
if labels and in labels:
kwargs['label'] = labels[]
if help_texts and in help_texts:
kwargs['help_text'] = help_texts[]
if error_messages and in error_messages:
kwargs['error_messages'] = error_messages[]
if field_classes and in field_classes:
kwargs['form_class'] = field_classes[]
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:
# Apply ``limit_choices_to``.
if hasattr(formfield, 'queryset') and hasattr(formfield, 'get_limit_choices_to'):
limit_choices_to = formfield.get_limit_choices_to()
if limit_choices_to is not None:
formfield.queryset = formfield.queryset.complex_filter(limit_choices_to)
field_list.append((, formfield))
field_dict = OrderedDict(field_list)
if fields:
field_dict = OrderedDict(
[(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:
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)
self.localized_fields = getattr(options, 'localized_fields', None)
self.labels = getattr(options, 'labels', None)
self.help_texts = getattr(options, 'help_texts', None)
self.error_messages = getattr(options, 'error_messages', None)
self.field_classes = getattr(options, 'field_classes', None)
class ModelFormMetaclass(DeclarativeFieldsMetaclass):
def __new__(mcs, name, bases, attrs):
base_formfield_callback = None
for b in bases:
if hasattr(b, 'Meta') and hasattr(b.Meta, 'formfield_callback'):
base_formfield_callback = b.Meta.formfield_callback
formfield_callback = attrs.pop('formfield_callback', base_formfield_callback)
new_class = super(ModelFormMetaclass, mcs).__new__(mcs, name, bases, attrs)
if bases == (BaseModelForm,):
return new_class
opts = new_class._meta = ModelFormOptions(getattr(new_class, 'Meta', None))
# We check if a string was passed to `fields` or `exclude`,
# which is likely to be a mistake where the user typed ('foo') instead
# of ('foo',)
for opt in ['fields', 'exclude', 'localized_fields']:
value = getattr(opts, opt)
if isinstance(value, str) and value != ALL_FIELDS:
msg = ("%(model)s.Meta.%(opt)s cannot be a string. "
"Did you mean to type: ('%(value)s',)?" % {
'model': new_class.__name__,
'opt': opt,
'value': value,
raise TypeError(msg)
if opts.model:
# If a model is defined, extract form fields from it.
if opts.fields is None and opts.exclude is None:
raise ImproperlyConfigured(
"Creating a ModelForm without either the 'fields' attribute "
"or the 'exclude' attribute is prohibited; form %s "
"needs updating." % name
if opts.fields == ALL_FIELDS:
# Sentinel for fields_for_model to indicate "get the list of
# fields from the model"
opts.fields = None
fields = fields_for_model(opts.model, opts.fields, opts.exclude,
opts.widgets, formfield_callback,
opts.localized_fields, opts.labels,
opts.help_texts, opts.error_messages,
# make sure opts.fields doesn't specify an invalid field
none_model_fields = [k for k, v in fields.items() if not v]
missing_fields = set(none_model_fields) - set(new_class.declared_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 = new_class.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=None,
empty_permitted=False, instance=None, use_required_attribute=None):
opts = self._meta
if opts.model is None:
raise ValueError('ModelForm has no model class specified.')
if instance is None:
# 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
data, files, auto_id, prefix, object_data, error_class,
label_suffix, empty_permitted, use_required_attribute=use_required_attribute,
def _get_validation_exclusions(self):
For backwards-compatibility, exclude several types of fields from model
validation. See tickets #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:
# 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)
if not f.blank and not form_field.required and field_value in form_field.empty_values:
return exclude
def clean(self):
self._validate_unique = True
return self.cleaned_data
def _update_errors(self, errors):
# Override any validation error messages defined at the model level
# with those defined at the form level.
opts = self._meta
# Allow the model generated by construct_instance() to raise
# ValidationError and have them handled in the same way as others.
if hasattr(errors, 'error_dict'):
error_dict = errors.error_dict
error_dict = {NON_FIELD_ERRORS: errors}
for field, messages in error_dict.items():
if (field == NON_FIELD_ERRORS and opts.error_messages and
NON_FIELD_ERRORS in opts.error_messages):
error_messages = opts.error_messages[NON_FIELD_ERRORS]
elif field in self.fields:
error_messages = self.fields[field].error_messages
for message in messages:
if (isinstance(message, ValidationError) and
message.code in error_messages):
message.message = error_messages[message.code]
self.add_error(None, errors)
def _post_clean(self):
opts = self._meta
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 name, field in self.fields.items():
if isinstance(field, InlineForeignKeyField):
self.instance = construct_instance(self, self.instance, opts.fields, opts.exclude)
except ValidationError as e:
self.instance.full_clean(exclude=exclude, validate_unique=False)
except ValidationError as e:
# Validate uniqueness if needed.
if self._validate_unique:
def validate_unique(self):
Call the instance's validate_unique() method and update the form's
validation errors if any were raised.
exclude = self._get_validation_exclusions()
except ValidationError as e:
def _save_m2m(self):
Save the many-to-many fields and generic relations for this form.
cleaned_data = self.cleaned_data
exclude = self._meta.exclude
fields = self._meta.fields
opts = self.instance._meta
# Note that for historical reasons we want to include also
# private_fields here. (GenericRelation was previously a fake
# m2m field).
for f in chain(opts.many_to_many, opts.private_fields):
if not hasattr(f, 'save_form_data'):
if fields and not in fields:
if exclude and in exclude:
if in cleaned_data:
f.save_form_data(self.instance, cleaned_data[])
def save(self, commit=True):
Save this form's self.instance object if commit=True. Otherwise, add
a save_m2m() method to the form which can be called after the instance
is saved manually at a later time. Return the model instance.
if self.errors:
raise ValueError(
"The %s could not be %s because the data didn't validate." % (
'created' if self.instance._state.adding else 'changed',
if commit:
# If committing, save the instance and the m2m data immediately.
# If not committing, add a method to the form to allow deferred
# saving of m2m data.
self.save_m2m = self._save_m2m
return self.instance
save.alters_data = True
class ModelForm(BaseModelForm, metaclass=ModelFormMetaclass):
def modelform_factory(model, form=ModelForm, fields=None, exclude=None,
formfield_callback=None, widgets=None, localized_fields=None,
labels=None, help_texts=None, error_messages=None,
Return a ModelForm containing form fields for the given model.
``fields`` is an optional list of field names. If provided, include only
the named fields in the returned fields. If omitted or '__all__', use all
``exclude`` is an optional list of field names. If provided, exclude the
named fields from the returned fields, even if they are listed in the
``fields`` argument.
``widgets`` is a dictionary of model field names mapped to a widget.
``localized_fields`` is a list of names of fields which should be localized.
``formfield_callback`` is a callable that takes a model field and returns
a form field.
``labels`` is a dictionary of model field names mapped to a label.
``help_texts`` is a dictionary of model field names mapped to a help text.
``error_messages`` is a dictionary of model field names mapped to a
dictionary of error messages.
``field_classes`` is a dictionary of model field names mapped to a form
field class.
# 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 localized_fields is not None:
attrs['localized_fields'] = localized_fields
if labels is not None:
attrs['labels'] = labels
if help_texts is not None:
attrs['help_texts'] = help_texts
if error_messages is not None:
attrs['error_messages'] = error_messages
if field_classes is not None:
attrs['field_classes'] = field_classes
# If parent form class already has an inner Meta, the Meta we're
# creating needs to inherit from the parent's inner meta.
bases = (form.Meta,) if hasattr(form, 'Meta') else ()
Meta = type('Meta', bases, attrs)
if formfield_callback:
Meta.formfield_callback = staticmethod(formfield_callback)
# 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
if (getattr(Meta, 'fields', None) is None and
getattr(Meta, 'exclude', None) is None):
raise ImproperlyConfigured(
"Calling modelform_factory without defining 'fields' or "
"'exclude' explicitly is prohibited."
# Instantiate type(form) in order to use the same metaclass as form.
return type(form)(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
# Set of fields that must be unique among forms of this set.
unique_fields = set()
def __init__(self, data=None, files=None, auto_id='id_%s', prefix=None,
queryset=None, *, initial=None, **kwargs):
self.queryset = queryset
self.initial_extra = initial
defaults = {'data': data, 'files': files, 'auto_id': auto_id, 'prefix': prefix}
def initial_form_count(self):
"""Return the number of forms that are required in this FormSet."""
if not ( or self.files):
return len(self.get_queryset())
return super().initial_form_count()
def _existing_object(self, pk):
if not hasattr(self, '_object_dict'):
self._object_dict = { o for o in self.get_queryset()}
return self._object_dict.get(pk)
def _get_to_python(self, field):
If the field is a related field, fetch the concrete field's (that
is, the ultimate pointed-to field's) to_python.
while field.remote_field is not None:
field = field.remote_field.get_related_field()
return field.to_python
def _construct_form(self, i, **kwargs):
if self.is_bound and i < self.initial_form_count():
pk_key = "%s-%s" % (self.add_prefix(i),
pk =[pk_key]
pk_field =
to_python = self._get_to_python(pk_field)
pk = to_python(pk)
kwargs['instance'] = self._existing_object(pk)
if i < self.initial_form_count() and 'instance' not in kwargs:
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()._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_queryset()
# 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):
"""Save and return a new model instance for the given form."""
def save_existing(self, form, instance, commit=True):
"""Save and return an existing model instance for the given form."""
def delete_existing(self, obj, commit=True):
"""Deletes an existing model instance."""
if commit:
def save(self, commit=True):
Save model instances for every form, adding and changing instances
as necessary, and return 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)
save.alters_data = True
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()
forms_to_delete = self.deleted_forms
valid_forms = [form for form in self.forms if form.is_valid() and form not in forms_to_delete]
for form in valid_forms:
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 valid_forms:
# Get the data for the set of fields that must be unique among the forms.
row_data = (
field if field in self.unique_fields else form.cleaned_data[field]
for field in unique_check if field in form.cleaned_data
# Reduce Model instances to their primary key values
row_data = tuple(d._get_pk_val() if hasattr(d, '_get_pk_val') else d
for d in row_data)
if row_data and None not in row_data:
# if we've already 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()])
# remove the data from the cleaned_data dict since it was invalid
for field in unique_check:
if field in form.cleaned_data:
del form.cleaned_data[field]
# 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 valid_forms:
# 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 already 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()])
# remove the data from the cleaned_data dict since it was invalid
del form.cleaned_data[field]
# mark the data as seen
if errors:
raise ValidationError(errors)
def get_unique_error_message(self, unique_check):
if len(unique_check) == 1:
return gettext("Please correct the duplicate data for %(field)s.") % {
"field": unique_check[0],
return gettext("Please correct the duplicate data for %(field)s, which must be unique.") % {
"field": get_text_list(unique_check, _("and")),
def get_date_error_message(self, date_check):
return gettext(
"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': str(date_check[1]),
def get_form_error(self):
return gettext("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 = []
forms_to_delete = self.deleted_forms
for form in self.initial_forms:
obj = form.instance
# If the pk is None, it means either:
# 1. The object is an unexpected empty model, created by invalid
# POST data such as an object outside the formset's queryset.
# 2. The object was already deleted from the database.
if is None:
if form in forms_to_delete:
self.delete_existing(obj, commit=commit)
elif 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.remote_field and pk.remote_field.parent_link and
if pk_is_not_editable(pk) or not in form.fields:
if form.is_bound:
# If we're adding the related instance, ignore its primary key
# as it could be an auto-generated default which isn't actually
# in the database.
pk_value = None if form.instance._state.adding else
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 = pk.remote_field.model._default_manager.get_queryset()
qs = self.model._default_manager.get_queryset()
qs = qs.using(form.instance._state.db)
if form._meta.widgets:
widget = form._meta.widgets.get(, HiddenInput)
widget = HiddenInput
form.fields[] = ModelChoiceField(qs, initial=pk_value, required=False, widget=widget)
super().add_fields(form, index)
def modelformset_factory(model, form=ModelForm, formfield_callback=None,
formset=BaseModelFormSet, extra=1, can_delete=False,
can_order=False, max_num=None, fields=None, exclude=None,
widgets=None, validate_max=False, localized_fields=None,
labels=None, help_texts=None, error_messages=None,
min_num=None, validate_min=False, field_classes=None):
"""Return a FormSet class for the given Django model class."""
meta = getattr(form, 'Meta', None)
if (getattr(meta, 'fields', fields) is None and
getattr(meta, 'exclude', exclude) is None):
raise ImproperlyConfigured(
"Calling modelformset_factory without defining 'fields' or "
"'exclude' explicitly is prohibited."
form = modelform_factory(model, form=form, fields=fields, exclude=exclude,
widgets=widgets, localized_fields=localized_fields,
labels=labels, help_texts=help_texts,
error_messages=error_messages, field_classes=field_classes)
FormSet = formset_factory(form, formset, extra=extra, min_num=min_num, max_num=max_num,
can_order=can_order, can_delete=can_delete,
validate_min=validate_min, validate_max=validate_max)
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):
if instance is None:
self.instance =
self.instance = instance
self.save_as_new = save_as_new
if queryset is None:
queryset = self.model._default_manager
if is not None:
qs = queryset.filter(**{ self.instance})
qs = queryset.none()
self.unique_fields = {}
super().__init__(data, files, prefix=prefix, queryset=qs, **kwargs)
# Add the generated field to form._meta.fields if it's defined to make
# sure validation isn't skipped on that field.
if self.form._meta.fields and not in self.form._meta.fields:
if isinstance(self.form._meta.fields, tuple):
self.form._meta.fields = list(self.form._meta.fields)
def initial_form_count(self):
if self.save_as_new:
return 0
return super().initial_form_count()
def _construct_form(self, i, **kwargs):
form = super()._construct_form(i, **kwargs)
if self.save_as_new:
mutable = getattr(, '_mutable', None)
# Allow modifying an immutable QueryDict.
if mutable is not None: = True
# 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
if mutable is not None: = mutable
# Set the fk value here so that the form can do its validation.
fk_value =
if !=
fk_value = getattr(self.instance,
fk_value = getattr(fk_value, 'pk', fk_value)
setattr(form.instance,, fk_value)
return form
def get_default_prefix(cls):
return'+', '')
def save_new(self, form, commit=True):
# Ensure the latest copy of the related instance is present on each
# form (it may have been saved after the formset was originally
# instantiated).
setattr(form.instance,, self.instance)
# 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().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'] =
# If we're adding a new object, ignore a parent's auto-generated key
# as it will be regenerated on the save request.
if self.instance._state.adding:
if kwargs.get('to_field') is not None:
to_field = self.instance._meta.get_field(kwargs['to_field'])
to_field =
if to_field.has_default():
setattr(self.instance, to_field.attname, None)
form.fields[name] = InlineForeignKeyField(self.instance, **kwargs)
def get_unique_error_message(self, unique_check):
unique_check = [field for field in unique_check if field !=]
return super().get_unique_error_message(unique_check)
def _get_foreign_key(parent_model, model, fk_name=None, can_fail=False):
Find and return the ForeignKey from model to parent if there is one
(return 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. Unless can_fail is
True, raise an exception if there isn't a 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 \
(fk.remote_field.model != parent_model and
fk.remote_field.model not in parent_model._meta.get_parent_list()):
raise ValueError(
"fk_name '%s' is not a ForeignKey to '%s'." % (fk_name, parent_model._meta.label)
elif len(fks_to_parent) == 0:
raise ValueError(
"'%s' has no field named '%s'." % (model._meta.label, 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 (
f.remote_field.model == parent_model or
f.remote_field.model 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 ValueError(
"'%s' has no ForeignKey to '%s'." % (
raise ValueError(
"'%s' has more than one ForeignKey to '%s'." % (
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, formfield_callback=None,
widgets=None, validate_max=False, localized_fields=None,
labels=None, help_texts=None, error_messages=None,
min_num=None, validate_min=False, field_classes=None):
Return an ``InlineFormSet`` for the given kwargs.
``fk_name`` must be provided 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,
'min_num': min_num,
'max_num': max_num,
'widgets': widgets,
'validate_min': validate_min,
'validate_max': validate_max,
'localized_fields': localized_fields,
'labels': labels,
'help_texts': help_texts,
'error_messages': error_messages,
'field_classes': field_classes,
FormSet = modelformset_factory(model, **kwargs) = fk
return FormSet
# Fields #####################################################################
class InlineForeignKeyField(Field):
A basic integer field that deals with validating the given value to a
given parent instance in an inline.
widget = HiddenInput
default_error_messages = {
'invalid_choice': _('The inline value did not match the parent instance.'),
def __init__(self, parent_instance, *args, pk_field=False, to_field=None, **kwargs):
self.parent_instance = parent_instance
self.pk_field = pk_field
self.to_field = to_field
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
super().__init__(*args, **kwargs)
def clean(self, value):
if value in self.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 str(value) != str(orig):
raise ValidationError(self.error_messages['invalid_choice'], code='invalid_choice')
return self.parent_instance
def has_changed(self, initial, data):
return False
class ModelChoiceIterator:
def __init__(self, field):
self.field = field
self.queryset = field.queryset
def __iter__(self):
if self.field.empty_label is not None:
yield ("", self.field.empty_label)
queryset = self.queryset.all()
# Can't use iterator() when queryset uses prefetch_related()
if not queryset._prefetch_related_lookups:
queryset = queryset.iterator()
for obj in queryset:
yield self.choice(obj)
def __len__(self):
return (len(self.queryset) + (1 if self.field.empty_label is not None else 0))
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': _('Select a valid choice. That choice is not one of'
' the available choices.'),
iterator = ModelChoiceIterator
def __init__(self, queryset, *, empty_label="---------",
required=True, widget=None, label=None, initial=None,
help_text='', to_field_name=None, limit_choices_to=None,
if required and (initial is not None):
self.empty_label = None
self.empty_label = empty_label
# Call Field instead of ChoiceField __init__() because we don't need
# ChoiceField.__init__().
self, required=required, widget=widget, label=label,
initial=initial, help_text=help_text, **kwargs
self.queryset = queryset
self.limit_choices_to = limit_choices_to # limit the queryset later.
self.to_field_name = to_field_name
def get_limit_choices_to(self):
Return ``limit_choices_to`` for this form field.
If it is a callable, invoke it and return the result.
if callable(self.limit_choices_to):
return self.limit_choices_to()
return self.limit_choices_to
def __deepcopy__(self, memo):
result = super(ChoiceField, self).__deepcopy__(memo)
# Need to force a new ModelChoiceIterator to be created, bug #11183
if self.queryset is not None:
result.queryset = self.queryset.all()
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):
Convert objects into strings and generate the labels for the choices
presented by this object. Subclasses can override this method to
customize the display of the choices.
return str(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 self.iterator(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().prepare_value(value)
def to_python(self, value):
if value in self.empty_values:
return None
key = self.to_field_name or 'pk'
value = self.queryset.get(**{key: value})
except (ValueError, TypeError, self.queryset.model.DoesNotExist):
raise ValidationError(self.error_messages['invalid_choice'], code='invalid_choice')
return value
def validate(self, value):
return Field.validate(self, value)
def has_changed(self, initial, data):
initial_value = initial if initial is not None else ''
data_value = data if data is not None else ''
return str(self.prepare_value(initial_value)) != str(data_value)
class ModelMultipleChoiceField(ModelChoiceField):
"""A MultipleChoiceField whose choices are a model QuerySet."""
widget = SelectMultiple
hidden_widget = MultipleHiddenInput
default_error_messages = {
'list': _('Enter a list of values.'),
'invalid_choice': _('Select a valid choice. %(value)s is not one of the'
' available choices.'),
'invalid_pk_value': _('"%(pk)s" is not a valid value.')
def __init__(self, queryset, **kwargs):
super().__init__(queryset, empty_label=None, **kwargs)
def to_python(self, value):
if not value:
return []
return list(self._check_values(value))
def clean(self, value):
value = self.prepare_value(value)
if self.required and not value:
raise ValidationError(self.error_messages['required'], code='required')
elif not self.required and not value:
return self.queryset.none()
if not isinstance(value, (list, tuple)):
raise ValidationError(self.error_messages['list'], code='list')
qs = self._check_values(value)
# Since this overrides the inherited ModelChoiceField.clean
# we run custom validators here
return qs
def _check_values(self, value):
Given a list of possible PK values, return a QuerySet of the
corresponding objects. Raise a ValidationError if a given value is
invalid (not a valid PK, not in the queryset, etc.)
key = self.to_field_name or 'pk'
# deduplicate given values to avoid creating many querysets or
# requiring the database backend deduplicate efficiently.
value = frozenset(value)
except TypeError:
# list of lists isn't hashable, for example
raise ValidationError(
for pk in value:
self.queryset.filter(**{key: pk})
except (ValueError, TypeError):
raise ValidationError(
params={'pk': pk},
qs = self.queryset.filter(**{'%s__in' % key: value})
pks = {str(getattr(o, key)) for o in qs}
for val in value:
if str(val) not in pks:
raise ValidationError(
params={'value': val},
return qs
def prepare_value(self, value):
if (hasattr(value, '__iter__') and
not isinstance(value, str) and
not hasattr(value, '_meta')):
prepare_value = super().prepare_value
return [prepare_value(v) for v in value]
return super().prepare_value(value)
def has_changed(self, initial, data):
if initial is None:
initial = []
if data is None:
data = []
if len(initial) != len(data):
return True
initial_set = {str(value) for value in self.prepare_value(initial)}
data_set = {str(value) for value in data}
return data_set != initial_set
def modelform_defines_fields(form_class):
return (form_class is not None and (
hasattr(form_class, '_meta') and
(form_class._meta.fields is not None or
form_class._meta.exclude is not None)