def __init__(self, to, to_field=None, rel_class=ManyToOneRel, **kwargs):
        try:
            to_name = to._meta.object_name.lower()
        except __HOLE__: # to._meta doesn't exist, so it must be RECURSIVE_RELATIONSHIP_CONSTANT
            assert isinstance(to, basestring), "%s(%r) is invalid. First parameter to ForeignKey must be either a model, a model name, or the string %r" % (self.__class__.__name__, to, RECURSIVE_RELATIONSHIP_CONSTANT)
        else:
            assert not to._meta.abstract, "%s cannot define a relation with abstract class %s" % (self.__class__.__name__, to._meta.object_name)
            to_field = to_field or to._meta.pk.name
        kwargs['verbose_name'] = kwargs.get('verbose_name', None)

        kwargs['rel'] = rel_class(to, to_field,
            related_name=kwargs.pop('related_name', None),
            limit_choices_to=kwargs.pop('limit_choices_to', None),
            lookup_overrides=kwargs.pop('lookup_overrides', None),
            parent_link=kwargs.pop('parent_link', False))
        Field.__init__(self, **kwargs)

        self.db_index = True
dataset/ETHPy150Open CollabQ/CollabQ/vendor/django/db/models/fields/related.py/ForeignKey.__init__