diff -r 000000000000 -r 0d40e90630ef web/lib/django/forms/models.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/web/lib/django/forms/models.py	Wed Jan 20 00:34:04 2010 +0100
@@ -0,0 +1,1033 @@
+"""
+Helper functions for creating Form classes from Django models
+and database field objects.
+"""
+
+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
+
+from util import ValidationError, ErrorList
+from forms import BaseForm, get_declared_fields, NON_FIELD_ERRORS
+from fields import Field, ChoiceField, IntegerField, EMPTY_VALUES
+from widgets import Select, SelectMultiple, HiddenInput, MultipleHiddenInput
+from widgets import media_property
+from formsets import BaseFormSet, formset_factory, DELETION_FIELD_NAME
+
+try:
+    set
+except NameError:
+    from sets import Set as set     # Python 2.3 fallback
+
+__all__ = (
+    'ModelForm', 'BaseModelForm', 'model_to_dict', 'fields_for_model',
+    'save_instance', 'form_for_fields', 'ModelChoiceField',
+    'ModelMultipleChoiceField',
+)
+
+
+def save_instance(form, instance, fields=None, fail_message='saved',
+                  commit=True, exclude=None):
+    """
+    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``.
+    """
+    from django.db import models
+    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))
+    cleaned_data = form.cleaned_data
+    file_field_list = []
+    for f in opts.fields:
+        if not f.editable or isinstance(f, models.AutoField) \
+                or not f.name in cleaned_data:
+            continue
+        if fields and f.name not in fields:
+            continue
+        if exclude and f.name in exclude:
+            continue
+        # OneToOneField doesn't allow assignment of None. Guard against that
+        # instead of allowing it and throwing an error.
+        if isinstance(f, models.OneToOneField) and cleaned_data[f.name] is None:
+            continue
+        # 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):
+            file_field_list.append(f)
+        else:
+            f.save_form_data(instance, cleaned_data[f.name])
+
+    for f in file_field_list:
+        f.save_form_data(instance, cleaned_data[f.name])
+
+    # Wrap up the saving of m2m data as a function.
+    def save_m2m():
+        opts = instance._meta
+        cleaned_data = form.cleaned_data
+        for f in opts.many_to_many:
+            if fields and f.name not in fields:
+                continue
+            if f.name in cleaned_data:
+                f.save_form_data(instance, cleaned_data[f.name])
+    if commit:
+        # If we are committing, save the instance and the m2m data immediately.
+        instance.save()
+        save_m2m()
+    else:
+        # We're not committing. Add a method to the form to allow deferred
+        # saving of m2m data.
+        form.save_m2m = save_m2m
+    return instance
+
+def make_model_save(model, fields, fail_message):
+    """Returns the save() method for a Form."""
+    def save(self, commit=True):
+        return save_instance(self, model(), fields, fail_message, commit)
+    return save
+
+def make_instance_save(instance, fields, fail_message):
+    """Returns the save() method for a Form."""
+    def save(self, commit=True):
+        return save_instance(self, instance, fields, fail_message, commit)
+    return save
+
+def form_for_fields(field_list):
+    """
+    Returns a Form class for the given list of Django database field instances.
+    """
+    fields = SortedDict([(f.name, f.formfield())
+                         for f in field_list if f.editable])
+    return type('FormForFields', (BaseForm,), {'base_fields': fields})
+
+
+# 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, OneToOneField
+    opts = instance._meta
+    data = {}
+    for f in opts.fields + opts.many_to_many:
+        if not f.editable:
+            continue
+        if fields and not f.name in fields:
+            continue
+        if exclude and f.name in exclude:
+            continue
+        if isinstance(f, ManyToManyField):
+            # If the object doesn't have a primry key yet, just use an empty
+            # list for its m2m fields. Calling f.value_from_object will raise
+            # an exception.
+            if instance.pk is None:
+                data[f.name] = []
+            else:
+                # MultipleChoiceWidget needs a list of pks, not object instances.
+                data[f.name] = [obj.pk for obj in f.value_from_object(instance)]
+        else:
+            data[f.name] = f.value_from_object(instance)
+    return data
+
+def fields_for_model(model, fields=None, exclude=None, formfield_callback=lambda f: f.formfield()):
+    """
+    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 = []
+    opts = model._meta
+    for f in opts.fields + opts.many_to_many:
+        if not f.editable:
+            continue
+        if fields and not f.name in fields:
+            continue
+        if exclude and f.name in exclude:
+            continue
+        formfield = formfield_callback(f)
+        if formfield:
+            field_list.append((f.name, 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)])
+    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)
+
+
+class ModelFormMetaclass(type):
+    def __new__(cls, name, bases, attrs):
+        formfield_callback = attrs.pop('formfield_callback',
+                lambda f: f.formfield())
+        try:
+            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,
+                attrs)
+        if not parents:
+            return new_class
+
+        if 'media' not in attrs:
+            new_class.media = 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, formfield_callback)
+            # Override default model fields with any custom declared ones
+            # (plus, include all the other declared fields).
+            fields.update(declared_fields)
+        else:
+            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 we didn't get an instance, instantiate a new one
+            self.instance = opts.model()
+            object_data = {}
+        else:
+            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:
+            object_data.update(initial)
+        super(BaseModelForm, self).__init__(data, files, auto_id, prefix, object_data,
+                                            error_class, label_suffix, empty_permitted)
+
+    def clean(self):
+        self.validate_unique()
+        return self.cleaned_data
+
+    def validate_unique(self):
+        unique_checks, date_checks = self._get_unique_checks()
+        form_errors = []
+        bad_fields = set()
+
+        field_errors, global_errors = self._perform_unique_checks(unique_checks)
+        bad_fields.union(field_errors)
+        form_errors.extend(global_errors)
+
+        field_errors, global_errors = self._perform_date_checks(date_checks)
+        bad_fields.union(field_errors)
+        form_errors.extend(global_errors)
+
+        for field_name in bad_fields:
+            del self.cleaned_data[field_name]
+        if form_errors:
+            # Raise the unique together errors since they are considered
+            # form-wide.
+            raise ValidationError(form_errors)
+
+    def _get_unique_checks(self):
+        from django.db.models.fields import FieldDoesNotExist, Field as ModelField
+
+        # Gather a list of checks to perform. We only perform unique checks
+        # for fields present and not None in cleaned_data.  Since this is a
+        # ModelForm, some fields may have been excluded; we can't perform a unique
+        # check on a form that is missing fields involved in that check.  It also does
+        # not make sense to check data that didn't validate, and since NULL does not
+        # equal NULL in SQL we should not do any unique checking for NULL values.
+        unique_checks = []
+        # these are checks for the unique_for_<date/year/month>
+        date_checks = []
+        for check in self.instance._meta.unique_together[:]:
+            fields_on_form = [field for field in check if self.cleaned_data.get(field) is not None]
+            if len(fields_on_form) == len(check):
+                unique_checks.append(check)
+
+        # Gather a list of checks for fields declared as unique and add them to
+        # the list of checks. Again, skip empty fields and any that did not validate.
+        for name in self.fields:
+            try:
+                f = self.instance._meta.get_field_by_name(name)[0]
+            except FieldDoesNotExist:
+                # This is an extra field that's not on the ModelForm, ignore it
+                continue
+            if not isinstance(f, ModelField):
+                # This is an extra field that happens to have a name that matches,
+                # for example, a related object accessor for this model.  So
+                # get_field_by_name found it, but it is not a Field so do not proceed
+                # to use it as if it were.
+                continue
+            if self.cleaned_data.get(name) is None:
+                continue
+            if f.unique:
+                unique_checks.append((name,))
+            if f.unique_for_date and self.cleaned_data.get(f.unique_for_date) is not None:
+                date_checks.append(('date', name, f.unique_for_date))
+            if f.unique_for_year and self.cleaned_data.get(f.unique_for_year) is not None:
+                date_checks.append(('year', name, f.unique_for_year))
+            if f.unique_for_month and self.cleaned_data.get(f.unique_for_month) is not None:
+                date_checks.append(('month', name, f.unique_for_month))
+        return unique_checks, date_checks
+
+
+    def _perform_unique_checks(self, unique_checks):
+        bad_fields = set()
+        form_errors = []
+
+        for unique_check in unique_checks:
+            # Try to look up an existing object with the same values as this
+            # object's values for all the unique field.
+
+            lookup_kwargs = {}
+            for field_name in unique_check:
+                lookup_value = self.cleaned_data[field_name]
+                # ModelChoiceField will return an object instance rather than
+                # a raw primary key value, so convert it to a pk value before
+                # using it in a lookup.
+                if isinstance(self.fields[field_name], ModelChoiceField):
+                    lookup_value =  lookup_value.pk
+                lookup_kwargs[str(field_name)] = lookup_value
+
+            qs = self.instance.__class__._default_manager.filter(**lookup_kwargs)
+
+            # Exclude the current object from the query if we are editing an
+            # instance (as opposed to creating a new one)
+            if self.instance.pk is not None:
+                qs = qs.exclude(pk=self.instance.pk)
+
+            # This cute trick with extra/values is the most efficient way to
+            # tell if a particular query returns any results.
+            if qs.extra(select={'a': 1}).values('a').order_by():
+                if len(unique_check) == 1:
+                    self._errors[unique_check[0]] = ErrorList([self.unique_error_message(unique_check)])
+                else:
+                    form_errors.append(self.unique_error_message(unique_check))
+
+                # Mark these fields as needing to be removed from cleaned data
+                # later.
+                for field_name in unique_check:
+                    bad_fields.add(field_name)
+        return bad_fields, form_errors
+
+    def _perform_date_checks(self, date_checks):
+        bad_fields = set()
+        for lookup_type, field, unique_for in date_checks:
+            lookup_kwargs = {}
+            # there's a ticket to add a date lookup, we can remove this special
+            # case if that makes it's way in
+            if lookup_type == 'date':
+                date = self.cleaned_data[unique_for]
+                lookup_kwargs['%s__day' % unique_for] = date.day
+                lookup_kwargs['%s__month' % unique_for] = date.month
+                lookup_kwargs['%s__year' % unique_for] = date.year
+            else:
+                lookup_kwargs['%s__%s' % (unique_for, lookup_type)] = getattr(self.cleaned_data[unique_for], lookup_type)
+            lookup_kwargs[field] = self.cleaned_data[field]
+
+            qs = self.instance.__class__._default_manager.filter(**lookup_kwargs)
+            # Exclude the current object from the query if we are editing an
+            # instance (as opposed to creating a new one)
+            if self.instance.pk is not None:
+                qs = qs.exclude(pk=self.instance.pk)
+
+            # This cute trick with extra/values is the most efficient way to
+            # tell if a particular query returns any results.
+            if qs.extra(select={'a': 1}).values('a').order_by():
+                self._errors[field] = ErrorList([
+                    self.date_error_message(lookup_type, field, unique_for)
+                ])
+                bad_fields.add(field)
+        return bad_fields, []
+
+    def date_error_message(self, lookup_type, field, unique_for):
+        return _(u"%(field_name)s must be unique for %(date_field)s %(lookup)s.") % {
+            'field_name': unicode(self.fields[field].label),
+            'date_field': unicode(self.fields[unique_for].label),
+            'lookup': lookup_type,
+        }
+
+    def unique_error_message(self, unique_check):
+        model_name = capfirst(self.instance._meta.verbose_name)
+
+        # A unique field
+        if len(unique_check) == 1:
+            field_name = unique_check[0]
+            field_label = self.fields[field_name].label
+            # Insert the error into the error dict, very sneaky
+            return _(u"%(model_name)s with this %(field_label)s already exists.") %  {
+                'model_name': unicode(model_name),
+                'field_label': unicode(field_label)
+            }
+        # unique_together
+        else:
+            field_labels = [self.fields[field_name].label for field_name in unique_check]
+            field_labels = get_text_list(field_labels, _('and'))
+            return _(u"%(model_name)s with this %(field_label)s already exists.") %  {
+                'model_name': unicode(model_name),
+                'field_label': unicode(field_labels)
+            }
+
+    def save(self, commit=True):
+        """
+        Saves this ``form``'s cleaned_data into model instance
+        ``self.instance``.
+
+        If commit=True, then the changes to ``instance`` will be saved to the
+        database. Returns ``instance``.
+        """
+        if self.instance.pk is None:
+            fail_message = 'created'
+        else:
+            fail_message = 'changed'
+        return save_instance(self, self.instance, self._meta.fields,
+                             fail_message, commit, exclude=self._meta.exclude)
+
+    save.alters_data = True
+
+class ModelForm(BaseModelForm):
+    __metaclass__ = ModelFormMetaclass
+
+def modelform_factory(model, form=ModelForm, fields=None, exclude=None,
+                       formfield_callback=lambda f: f.formfield()):
+    # 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 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
+    }
+
+    return ModelFormMetaclass(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
+        defaults = {'data': data, 'files': files, 'auto_id': auto_id, 'prefix': prefix}
+        defaults.update(kwargs)
+        super(BaseModelFormSet, self).__init__(**defaults)
+
+    def initial_form_count(self):
+        """Returns the number of forms that are required in this FormSet."""
+        if not (self.data 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.pk, 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():
+            pk_key = "%s-%s" % (self.add_prefix(i), self.model._meta.pk.name)
+            pk = self.data[pk_key]
+            pk_field = self.model._meta.pk
+            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]
+        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
+            else:
+                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(self.model._meta.pk.name)
+
+            if self.max_num > 0:
+                self._queryset = qs[:self.max_num]
+            else:
+                self._queryset = qs
+        return self._queryset
+
+    def save_new(self, form, commit=True):
+        """Saves and returns a new model instance for the given form."""
+        return form.save(commit=commit)
+
+    def save_existing(self, form, instance, commit=True):
+        """Saves and returns an existing model instance for the given form."""
+        return form.save(commit=commit)
+
+    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:
+                    form.save_m2m()
+            self.save_m2m = save_m2m
+        return self.save_existing_objects(commit) + self.save_new_objects(commit)
+
+    def clean(self):
+        self.validate_unique()
+
+    def validate_unique(self):
+        # Iterate over the forms so that we can find one with potentially valid
+        # data from which to extract the error checks
+        for form in self.forms:
+            if hasattr(form, 'cleaned_data'):
+                break
+        else:
+            return
+        unique_checks, date_checks = form._get_unique_checks()
+        errors = []
+        # Do each of the unique checks (unique and unique_together)
+        for unique_check in 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"):
+                    continue
+                # get each of the fields for which we have data on this form
+                if [f for f in unique_check if f in form.cleaned_data and form.cleaned_data[f] is not None]:
+                    # get the data itself
+                    row_data = tuple([form.cleaned_data[field] for field in unique_check])
+                    # 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
+                        errors.append(self.get_unique_error_message(unique_check))
+                        form._errors[NON_FIELD_ERRORS] = self.get_form_error()
+                        del form.cleaned_data
+                        break
+                    # mark the data as seen
+                    seen_data.add(row_data)
+        # iterate over each of the date checks now
+        for date_check in date_checks:
+            seen_data = set()
+            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'):
+                    continue
+                # 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, date.day)
+                    # otherwise it's just the attribute on the date/datetime
+                    # object
+                    else:
+                        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
+                        errors.append(self.get_date_error_message(date_check))
+                        form._errors[NON_FIELD_ERRORS] = self.get_form_error()
+                        del form.cleaned_data
+                        break
+                    seen_data.add(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],
+            }
+        else:
+            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[1],
+            'date_field': date_check[2],
+            'lookup': unicode(date_check[0]),
+        }
+
+    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.get_queryset():
+            return []
+
+        saved_instances = []
+        for form in self.initial_forms:
+            pk_name = self._pk_field.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:
+                raw_delete_value = form._raw_value(DELETION_FIELD_NAME)
+                should_delete = form.fields[DELETION_FIELD_NAME].clean(raw_delete_value)
+                if should_delete:
+                    self.deleted_objects.append(obj)
+                    obj.delete()
+                    continue
+            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:
+                    self.saved_forms.append(form)
+        return saved_instances
+
+    def save_new_objects(self, commit=True):
+        self.new_objects = []
+        for form in self.extra_forms:
+            if not form.has_changed():
+                continue
+            # If someone has marked an add form for deletion, don't save the
+            # object.
+            if self.can_delete:
+                raw_delete_value = form._raw_value(DELETION_FIELD_NAME)
+                should_delete = form.fields[DELETION_FIELD_NAME].clean(raw_delete_value)
+                if should_delete:
+                    continue
+            self.new_objects.append(self.save_new(form, commit=commit))
+            if not commit:
+                self.saved_forms.append(form)
+        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 = self.model._meta.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(pk.rel.to._meta.pk)))
+        if pk_is_not_editable(pk) or pk.name not in form.fields:
+            if form.is_bound:
+                pk_value = form.instance.pk
+            else:
+                try:
+                    pk_value = self.get_queryset()[index].pk
+                except IndexError:
+                    pk_value = None
+            if isinstance(pk, OneToOneField) or isinstance(pk, ForeignKey):
+                qs = pk.rel.to._default_manager.get_query_set()
+            else:
+                qs = self.model._default_manager.get_query_set()
+            form.fields[self._pk_field.name] = ModelChoiceField(qs, initial=pk_value, required=False, widget=HiddenInput)
+        super(BaseModelFormSet, self).add_fields(form, index)
+
+def modelformset_factory(model, form=ModelForm, formfield_callback=lambda f: f.formfield(),
+                         formset=BaseModelFormSet,
+                         extra=1, can_delete=False, can_order=False,
+                         max_num=0, fields=None, exclude=None):
+    """
+    Returns a FormSet class for the given Django model class.
+    """
+    form = modelform_factory(model, form=form, fields=fields, exclude=exclude,
+                             formfield_callback=formfield_callback)
+    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):
+        from django.db.models.fields.related import RelatedObject
+        if instance is None:
+            self.instance = self.model()
+        else:
+            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.fk.rel.to, self.model, self.fk).get_accessor_name()
+        if self.fk.rel.field_name == self.fk.rel.to._meta.pk.name:
+            backlink_value = self.instance
+        else:
+            backlink_value = getattr(self.instance, self.fk.rel.field_name)
+        qs = self.model._default_manager.filter(**{self.fk.name: backlink_value})
+        super(BaseInlineFormSet, self).__init__(data, files, prefix=prefix,
+                                                queryset=qs)
+
+    def initial_form_count(self):
+        if self.save_as_new:
+            return 0
+        return super(BaseInlineFormSet, self).initial_form_count()
+
+    def total_form_count(self):
+        if self.save_as_new:
+            return super(BaseInlineFormSet, self).initial_form_count()
+        return super(BaseInlineFormSet, self).total_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.data[form.add_prefix(self._pk_field.name)] = None
+
+            # Remove the foreign key from the form's data
+            form.data[form.add_prefix(self.fk.name)] = None
+        return form
+
+    #@classmethod
+    def get_default_prefix(cls):
+        from django.db.models.fields.related import RelatedObject
+        return RelatedObject(cls.fk.rel.to, cls.model, cls.fk).get_accessor_name()
+    get_default_prefix = classmethod(get_default_prefix)
+
+    def save_new(self, form, commit=True):
+        # Use commit=False so we can assign the parent key afterwards, then
+        # save the object.
+        obj = form.save(commit=False)
+        pk_value = getattr(self.instance, self.fk.rel.field_name)
+        setattr(obj, self.fk.get_attname(), getattr(pk_value, 'pk', pk_value))
+        if commit:
+            obj.save()
+        # form.save_m2m() can be called via the formset later on if commit=False
+        if commit and hasattr(form, 'save_m2m'):
+            form.save_m2m()
+        return obj
+
+    def add_fields(self, form, index):
+        super(BaseInlineFormSet, self).add_fields(form, index)
+        if self._pk_field == self.fk:
+            form.fields[self._pk_field.name] = InlineForeignKeyField(self.instance, pk_field=True)
+        else:
+            # 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.
+            kwargs = {
+                'label': getattr(form.fields.get(self.fk.name), 'label', capfirst(self.fk.verbose_name))
+            }
+            if self.fk.rel.field_name != self.fk.rel.to._meta.pk.name:
+                kwargs['to_field'] = self.fk.rel.field_name
+            form.fields[self.fk.name] = InlineForeignKeyField(self.instance, **kwargs)
+
+    def get_unique_error_message(self, unique_check):
+        unique_check = [field for field in unique_check if field != self.fk.name]
+        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
+    parent_model.
+    """
+    # 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 f.name == fk_name]
+        if len(fks_to_parent) == 1:
+            fk = fks_to_parent[0]
+            if not isinstance(fk, ForeignKey) or \
+                    (fk.rel.to != parent_model and
+                     fk.rel.to 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))
+    else:
+        # 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.rel.to == parent_model
+                or f.rel.to 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:
+                return
+            raise Exception("%s has no ForeignKey to %s" % (model, parent_model))
+        else:
+            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=0,
+                          formfield_callback=lambda f: f.formfield()):
+    """
+    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)
+    FormSet.fk = 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)
+            else:
+                kwargs["initial"] = self.parent_instance.pk
+        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)
+        else:
+            orig = self.parent_instance.pk
+        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
+        else:
+            for obj in self.queryset.all():
+                yield self.choice(obj)
+
+    def choice(self, obj):
+        if self.field.to_field_name:
+            key = obj.serializable_value(self.field.to_field_name)
+        else:
+            key = obj.pk
+        return (key, 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
+        else:
+            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 _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 QuerySetIterator that has not been
+        # consumed. Note that we're instantiating a new QuerySetIterator *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 clean(self, value):
+        Field.clean(self, value)
+        if value in EMPTY_VALUES:
+            return None
+        try:
+            key = self.to_field_name or 'pk'
+            value = self.queryset.get(**{key: value})
+        except self.queryset.model.DoesNotExist:
+            raise ValidationError(self.error_messages['invalid_choice'])
+        return 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'])
+        for pk in value:
+            try:
+                self.queryset.filter(pk=pk)
+            except ValueError:
+                raise ValidationError(self.error_messages['invalid_pk_value'] % pk)
+        qs = self.queryset.filter(pk__in=value)
+        pks = set([force_unicode(o.pk) for o in qs])
+        for val in value:
+            if force_unicode(val) not in pks:
+                raise ValidationError(self.error_messages['invalid_choice'] % val)
+        return qs