class BoundRelatedObject(object):

    def __init__(self, related_object, field_mapping, original):

        self.relation = related_object

        self.field_mappings = field_mapping[related_object.name]

    def template_name(self):

        raise NotImplementedError

    def __repr__(self):

        return repr(self.__dict__)

class RelatedObject(object):

    def __init__(self, parent_model, model, field):

        self.parent_model = parent_model

        self.model = model

        self.opts = model._meta

        self.field = field

        self.name = '%s:%s' % (self.opts.app_label, self.opts.module_name)

        self.var_name = self.opts.object_name.lower()

    def get_db_prep_lookup(self, lookup_type, value, connection, prepared=False):

        # Defer to the actual field definition for db prep

        return self.field.get_db_prep_lookup(lookup_type, value,

                        connection=connection, prepared=prepared)

    def editable_fields(self):

        "Get the fields in this class that should be edited inline."

        return [f for f in self.opts.fields + self.opts.many_to_many if f.editable and f != self.field]

    def __repr__(self):

        return "<RelatedObject: %s related to %s>" % (self.name, self.field.name)

    def bind(self, field_mapping, original, bound_related_object_class=BoundRelatedObject):

        return bound_related_object_class(self, field_mapping, original)

    def get_accessor_name(self):

        # This method encapsulates the logic that decides what name to give an

        # accessor descriptor that retrieves related many-to-one or

        # many-to-many objects. It uses the lower-cased object_name + "_set",

        # but this can be overridden with the "related_name" option.

        if self.field.rel.multiple:

            # If this is a symmetrical m2m relation on self, there is no reverse accessor.

            if getattr(self.field.rel, 'symmetrical', False) and self.model == self.parent_model:

                return None

            return self.field.rel.related_name or (self.opts.object_name.lower() + '_set')

        else:

            return self.field.rel.related_name or (self.opts.object_name.lower())

    def get_cache_name(self):

        return "_%s_cache" % self.get_accessor_name()