400 lines
16 KiB
Python
400 lines
16 KiB
Python
"""
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Helper functions for creating Form classes from Django models
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and database field objects.
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"""
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from warnings import warn
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from django.utils.translation import ugettext_lazy as _
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from django.utils.encoding import smart_unicode
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from django.utils.datastructures import SortedDict
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from django.core.exceptions import ImproperlyConfigured
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from util import ValidationError, ErrorList
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from forms import BaseForm, get_declared_fields
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from fields import Field, ChoiceField, EMPTY_VALUES
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from widgets import Select, SelectMultiple, MultipleHiddenInput
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__all__ = (
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'ModelForm', 'BaseModelForm', 'model_to_dict', 'fields_for_model',
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'save_instance', 'form_for_model', 'form_for_instance', 'form_for_fields',
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'ModelChoiceField', 'ModelMultipleChoiceField'
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)
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def save_instance(form, instance, fields=None, fail_message='saved',
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commit=True):
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"""
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Saves bound Form ``form``'s cleaned_data into model instance ``instance``.
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If commit=True, then the changes to ``instance`` will be saved to the
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database. Returns ``instance``.
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"""
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from django.db import models
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opts = instance.__class__._meta
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if form.errors:
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raise ValueError("The %s could not be %s because the data didn't"
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" validate." % (opts.object_name, fail_message))
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cleaned_data = form.cleaned_data
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for f in opts.fields:
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if not f.editable or isinstance(f, models.AutoField) \
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or not f.name in cleaned_data:
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continue
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if fields and f.name not in fields:
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continue
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f.save_form_data(instance, cleaned_data[f.name])
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# Wrap up the saving of m2m data as a function.
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def save_m2m():
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opts = instance.__class__._meta
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cleaned_data = form.cleaned_data
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for f in opts.many_to_many:
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if fields and f.name not in fields:
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continue
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if f.name in cleaned_data:
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f.save_form_data(instance, cleaned_data[f.name])
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if commit:
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# If we are committing, save the instance and the m2m data immediately.
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instance.save()
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save_m2m()
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else:
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# We're not committing. Add a method to the form to allow deferred
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# saving of m2m data.
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form.save_m2m = save_m2m
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return instance
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def make_model_save(model, fields, fail_message):
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"""Returns the save() method for a Form."""
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def save(self, commit=True):
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return save_instance(self, model(), fields, fail_message, commit)
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return save
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def make_instance_save(instance, fields, fail_message):
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"""Returns the save() method for a Form."""
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def save(self, commit=True):
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return save_instance(self, instance, fields, fail_message, commit)
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return save
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def form_for_model(model, form=BaseForm, fields=None,
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formfield_callback=lambda f: f.formfield()):
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"""
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Returns a Form class for the given Django model class.
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Provide ``form`` if you want to use a custom BaseForm subclass.
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Provide ``formfield_callback`` if you want to define different logic for
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determining the formfield for a given database field. It's a callable that
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takes a database Field instance and returns a form Field instance.
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"""
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warn("form_for_model is deprecated. Use ModelForm instead.",
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PendingDeprecationWarning, stacklevel=3)
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opts = model._meta
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field_list = []
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for f in opts.fields + opts.many_to_many:
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if not f.editable:
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continue
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if fields and not f.name in fields:
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continue
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formfield = formfield_callback(f)
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if formfield:
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field_list.append((f.name, formfield))
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base_fields = SortedDict(field_list)
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return type(opts.object_name + 'Form', (form,),
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{'base_fields': base_fields, '_model': model,
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'save': make_model_save(model, fields, 'created')})
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def form_for_instance(instance, form=BaseForm, fields=None,
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formfield_callback=lambda f, **kwargs: f.formfield(**kwargs)):
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"""
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Returns a Form class for the given Django model instance.
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Provide ``form`` if you want to use a custom BaseForm subclass.
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Provide ``formfield_callback`` if you want to define different logic for
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determining the formfield for a given database field. It's a callable that
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takes a database Field instance, plus **kwargs, and returns a form Field
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instance with the given kwargs (i.e. 'initial').
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"""
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warn("form_for_instance is deprecated. Use ModelForm instead.",
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PendingDeprecationWarning, stacklevel=3)
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model = instance.__class__
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opts = model._meta
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field_list = []
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for f in opts.fields + opts.many_to_many:
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if not f.editable:
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continue
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if fields and not f.name in fields:
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continue
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current_value = f.value_from_object(instance)
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formfield = formfield_callback(f, initial=current_value)
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if formfield:
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field_list.append((f.name, formfield))
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base_fields = SortedDict(field_list)
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return type(opts.object_name + 'InstanceForm', (form,),
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{'base_fields': base_fields, '_model': model,
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'save': make_instance_save(instance, fields, 'changed')})
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def form_for_fields(field_list):
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"""
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Returns a Form class for the given list of Django database field instances.
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"""
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fields = SortedDict([(f.name, f.formfield())
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for f in field_list if f.editable])
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return type('FormForFields', (BaseForm,), {'base_fields': fields})
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# ModelForms #################################################################
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def model_to_dict(instance, fields=None, exclude=None):
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"""
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Returns a dict containing the data in ``instance`` suitable for passing as
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a Form's ``initial`` keyword argument.
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``fields`` is an optional list of field names. If provided, only the named
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fields will be included in the returned dict.
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``exclude`` is an optional list of field names. If provided, the named
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fields will be excluded from the returned dict, even if they are listed in
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the ``fields`` argument.
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"""
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# avoid a circular import
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from django.db.models.fields.related import ManyToManyField
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opts = instance._meta
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data = {}
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for f in opts.fields + opts.many_to_many:
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if not f.editable:
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continue
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if fields and not f.name in fields:
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continue
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if exclude and f.name in exclude:
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continue
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if isinstance(f, ManyToManyField):
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# If the object doesn't have a primry key yet, just use an empty
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# list for its m2m fields. Calling f.value_from_object will raise
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# an exception.
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if instance.pk is None:
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data[f.name] = []
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else:
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# MultipleChoiceWidget needs a list of pks, not object instances.
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data[f.name] = [obj.pk for obj in f.value_from_object(instance)]
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else:
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data[f.name] = f.value_from_object(instance)
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return data
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def fields_for_model(model, fields=None, exclude=None, formfield_callback=lambda f: f.formfield()):
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"""
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Returns a ``SortedDict`` containing form fields for the given model.
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``fields`` is an optional list of field names. If provided, only the named
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fields will be included in the returned fields.
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``exclude`` is an optional list of field names. If provided, the named
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fields will be excluded from the returned fields, even if they are listed
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in the ``fields`` argument.
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"""
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# TODO: if fields is provided, it would be nice to return fields in that order
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field_list = []
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opts = model._meta
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for f in opts.fields + opts.many_to_many:
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if not f.editable:
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continue
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if fields and not f.name in fields:
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continue
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if exclude and f.name in exclude:
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continue
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formfield = formfield_callback(f)
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if formfield:
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field_list.append((f.name, formfield))
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return SortedDict(field_list)
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class ModelFormOptions(object):
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def __init__(self, options=None):
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self.model = getattr(options, 'model', None)
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self.fields = getattr(options, 'fields', None)
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self.exclude = getattr(options, 'exclude', None)
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class ModelFormMetaclass(type):
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def __new__(cls, name, bases, attrs,
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formfield_callback=lambda f: f.formfield()):
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try:
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parents = [b for b in bases if issubclass(b, ModelForm)]
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except NameError:
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# We are defining ModelForm itself.
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parents = None
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if not parents:
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return super(ModelFormMetaclass, cls).__new__(cls, name, bases,
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attrs)
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new_class = type.__new__(cls, name, bases, attrs)
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declared_fields = get_declared_fields(bases, attrs, False)
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opts = new_class._meta = ModelFormOptions(getattr(new_class, 'Meta', None))
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if opts.model:
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# If a model is defined, extract form fields from it.
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fields = fields_for_model(opts.model, opts.fields,
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opts.exclude, formfield_callback)
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# Override default model fields with any custom declared ones
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# (plus, include all the other declared fields).
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fields.update(declared_fields)
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else:
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fields = declared_fields
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new_class.declared_fields = declared_fields
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new_class.base_fields = fields
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return new_class
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class BaseModelForm(BaseForm):
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def __init__(self, data=None, files=None, auto_id='id_%s', prefix=None,
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initial=None, error_class=ErrorList, label_suffix=':',
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instance=None):
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opts = self._meta
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if instance is None:
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# if we didn't get an instance, instantiate a new one
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self.instance = opts.model()
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object_data = {}
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else:
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self.instance = instance
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object_data = model_to_dict(instance, opts.fields, opts.exclude)
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# if initial was provided, it should override the values from instance
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if initial is not None:
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object_data.update(initial)
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BaseForm.__init__(self, data, files, auto_id, prefix, object_data, error_class, label_suffix)
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def save(self, commit=True):
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"""
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Saves this ``form``'s cleaned_data into model instance
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``self.instance``.
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If commit=True, then the changes to ``instance`` will be saved to the
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database. Returns ``instance``.
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"""
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if self.instance.pk is None:
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fail_message = 'created'
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else:
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fail_message = 'changed'
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return save_instance(self, self.instance, self._meta.fields, fail_message, commit)
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class ModelForm(BaseModelForm):
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__metaclass__ = ModelFormMetaclass
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# Fields #####################################################################
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class ModelChoiceIterator(object):
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def __init__(self, field):
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self.field = field
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self.queryset = field.queryset
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def __iter__(self):
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if self.field.empty_label is not None:
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yield (u"", self.field.empty_label)
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if self.field.cache_choices:
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if self.field.choice_cache is None:
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self.field.choice_cache = [
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(obj.pk, self.field.label_from_instance(obj))
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for obj in self.queryset.all()
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]
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for choice in self.field.choice_cache:
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yield choice
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else:
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for obj in self.queryset.all():
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yield (obj.pk, self.field.label_from_instance(obj))
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class ModelChoiceField(ChoiceField):
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"""A ChoiceField whose choices are a model QuerySet."""
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# This class is a subclass of ChoiceField for purity, but it doesn't
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# actually use any of ChoiceField's implementation.
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default_error_messages = {
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'invalid_choice': _(u'Select a valid choice. That choice is not one of'
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u' the available choices.'),
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}
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def __init__(self, queryset, empty_label=u"---------", cache_choices=False,
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required=True, widget=Select, label=None, initial=None,
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help_text=None, *args, **kwargs):
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self.empty_label = empty_label
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self.cache_choices = cache_choices
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# Call Field instead of ChoiceField __init__() because we don't need
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# ChoiceField.__init__().
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Field.__init__(self, required, widget, label, initial, help_text,
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*args, **kwargs)
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self.queryset = queryset
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self.choice_cache = None
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def _get_queryset(self):
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return self._queryset
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def _set_queryset(self, queryset):
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self._queryset = queryset
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self.widget.choices = self.choices
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queryset = property(_get_queryset, _set_queryset)
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# this method will be used to create object labels by the QuerySetIterator.
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# Override it to customize the label.
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def label_from_instance(self, obj):
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"""
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This method is used to convert objects into strings; it's used to
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generate the labels for the choices presented by this object. Subclasses
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can override this method to customize the display of the choices.
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"""
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return smart_unicode(obj)
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def _get_choices(self):
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# If self._choices is set, then somebody must have manually set
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# the property self.choices. In this case, just return self._choices.
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if hasattr(self, '_choices'):
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return self._choices
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# Otherwise, execute the QuerySet in self.queryset to determine the
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# choices dynamically. Return a fresh QuerySetIterator that has not been
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# consumed. Note that we're instantiating a new QuerySetIterator *each*
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# time _get_choices() is called (and, thus, each time self.choices is
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# accessed) so that we can ensure the QuerySet has not been consumed. This
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# construct might look complicated but it allows for lazy evaluation of
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# the queryset.
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return ModelChoiceIterator(self)
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choices = property(_get_choices, ChoiceField._set_choices)
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def clean(self, value):
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Field.clean(self, value)
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if value in EMPTY_VALUES:
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return None
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try:
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value = self.queryset.get(pk=value)
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except self.queryset.model.DoesNotExist:
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raise ValidationError(self.error_messages['invalid_choice'])
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return value
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class ModelMultipleChoiceField(ModelChoiceField):
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"""A MultipleChoiceField whose choices are a model QuerySet."""
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hidden_widget = MultipleHiddenInput
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default_error_messages = {
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'list': _(u'Enter a list of values.'),
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'invalid_choice': _(u'Select a valid choice. %s is not one of the'
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u' available choices.'),
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}
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def __init__(self, queryset, cache_choices=False, required=True,
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widget=SelectMultiple, label=None, initial=None,
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help_text=None, *args, **kwargs):
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super(ModelMultipleChoiceField, self).__init__(queryset, None,
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cache_choices, required, widget, label, initial, help_text,
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*args, **kwargs)
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def clean(self, value):
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if self.required and not value:
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raise ValidationError(self.error_messages['required'])
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elif not self.required and not value:
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return []
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if not isinstance(value, (list, tuple)):
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raise ValidationError(self.error_messages['list'])
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final_values = []
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for val in value:
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try:
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obj = self.queryset.get(pk=val)
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except self.queryset.model.DoesNotExist:
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raise ValidationError(self.error_messages['invalid_choice'] % val)
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else:
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final_values.append(obj)
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return final_values
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