Source code for dal_contenttypes.fields
"""Model choice fields that take a ContentType too: for generic relations."""
from django.contrib.contenttypes.models import ContentType
[docs]
class ContentTypeModelFieldMixin(object):
"""
Common methods for form fields for GenericForeignKey.
ModelChoiceFieldMixin expects options to look like::
<option value="4">Model #4</option>
With a ContentType of id 3 for that model, it becomes::
<option value="3-4">Model #4</option>
"""
[docs]
def prepare_value(self, value):
"""Return a ctypeid-objpk string for value."""
if not value:
return ''
if isinstance(value, str):
# Apparently Django's ModelChoiceField also expects two kinds of
# "value" to be passed in this method.
return value
return '%s-%s' % (ContentType.objects.get_for_model(value).pk,
value.pk)
[docs]
class ContentTypeModelMultipleFieldMixin(ContentTypeModelFieldMixin):
"""Same as ContentTypeModelFieldMixin, but supports value list."""
[docs]
def prepare_value(self, value):
"""Run the parent's method for each value."""
if not value: # ModelMultipleChoiceField does it too
return []
return [
super(ContentTypeModelMultipleFieldMixin, self).prepare_value(v)
for v in value
]
[docs]
class GenericModelMixin(ContentTypeModelFieldMixin):
"""GenericForeignKey support for form fields, with FutureModelForm.
GenericForeignKey enforce editable=false, this class implements
save_object_data() and value_from_object() to allow FutureModelForm to
compensate.
"""
[docs]
def save_object_data(self, instance, name, value):
"""Set the attribute, for FutureModelForm."""
setattr(instance, name, value)
[docs]
def value_from_object(self, instance, name):
"""Get the attribute, for FutureModelForm."""
return getattr(instance, name)