- February 4, 2010
- foreign-key filterspec list-filter 3400
- 2 (after 2 ratings)
This is some (probably) pretty dodgy code that allows for foreign keys in the admin's list_filter without using a custom FilterSpec. It overrides the django.db.models.options.Options get_field class to handle spanned relationships, i.e. list_filter=('houseroomtown',) as seen in http://code.djangoproject.com/ticket/3400
I have only tested this with a double foreign key relationship('house__room'), and it worked. It hasn't been tested in production, and the troubling part of this code is probably to use of 'deepcopy'. I do add those copies back to the options instance, so there shouldn't be too much runaway copying.
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from django.db.models.fields import FieldDoesNotExist import copy from django.db.models.fields.related import ForeignKey def get_field(self, name, many_to_many=True): """ Returns the requested field by name. Raises FieldDoesNotExist on error. """ to_search = many_to_many and (self.fields + self.many_to_many) or self.fields if hasattr(self, '_copy_fields'): to_search += self._copy_fields for f in to_search: if f.name == name: return f if not name.startswith('__') and '__' in name: f = None model = self path = name.split('__') for field_name in path: f = model._get_field(field_name) if isinstance(f, ForeignKey): model = f.rel.to._meta f = copy.deepcopy(f) f.name = name if not hasattr(self, "_copy_fields"): self._copy_fields = list() self._copy_fields.append(f) return f raise FieldDoesNotExist, '%s has no field named %r' % (self.object_name, name) setattr(options.Options, '_get_field', options.Options.get_field.im_func) setattr(options.Options, 'get_field', get_field)