from django.db.models.fields.related import ( RECURSIVE_RELATIONSHIP_CONSTANT, ManyRelatedObjectsDescriptor, ManyToManyField, ManyToManyRel, RelatedField, create_many_to_many_intermediary_model, ) from django.utils.functional import curry class CustomManyToManyField(RelatedField): """ Ticket #24104 - Need to have a custom ManyToManyField, which is not an inheritor of ManyToManyField. """ many_to_many = True def __init__(self, to, db_constraint=True, swappable=True, **kwargs): try: to._meta except AttributeError: to = str(to) kwargs['rel'] = ManyToManyRel( self, to, related_name=kwargs.pop('related_name', None), related_query_name=kwargs.pop('related_query_name', None), limit_choices_to=kwargs.pop('limit_choices_to', None), symmetrical=kwargs.pop('symmetrical', to == RECURSIVE_RELATIONSHIP_CONSTANT), through=kwargs.pop('through', None), through_fields=kwargs.pop('through_fields', None), db_constraint=db_constraint, ) self.swappable = swappable self.db_table = kwargs.pop('db_table', None) if kwargs['rel'].through is not None: assert self.db_table is None, "Cannot specify a db_table if an intermediary model is used." super(CustomManyToManyField, self).__init__(**kwargs) def contribute_to_class(self, cls, name, **kwargs): if self.remote_field.symmetrical and ( self.remote_field.model == "self" or self.remote_field.model == cls._meta.object_name): self.remote_field.related_name = "%s_rel_+" % name super(CustomManyToManyField, self).contribute_to_class(cls, name, **kwargs) if not self.remote_field.through and not cls._meta.abstract and not cls._meta.swapped: self.remote_field.through = create_many_to_many_intermediary_model(self, cls) setattr(cls, self.name, ManyRelatedObjectsDescriptor(self.remote_field)) self.m2m_db_table = curry(self._get_m2m_db_table, cls._meta) def get_internal_type(self): return 'ManyToManyField' # Copy those methods from ManyToManyField because they don't call super() internally contribute_to_related_class = ManyToManyField.__dict__['contribute_to_related_class'] _get_m2m_attr = ManyToManyField.__dict__['_get_m2m_attr'] _get_m2m_reverse_attr = ManyToManyField.__dict__['_get_m2m_reverse_attr'] _get_m2m_db_table = ManyToManyField.__dict__['_get_m2m_db_table'] class InheritedManyToManyField(ManyToManyField): pass