related.py 文件源码

def deconstruct(self):
        name, path, args, kwargs = super(ForeignObject, self).deconstruct()
        kwargs['from_fields'] = self.from_fields
        kwargs['to_fields'] = self.to_fields
        if self.rel.related_name is not None:
            kwargs['related_name'] = self.rel.related_name
        if self.rel.related_query_name is not None:
            kwargs['related_query_name'] = self.rel.related_query_name
        if self.rel.on_delete != CASCADE:
            kwargs['on_delete'] = self.rel.on_delete
        if self.rel.parent_link:
            kwargs['parent_link'] = self.rel.parent_link
        # Work out string form of "to"
        if isinstance(self.rel.to, six.string_types):
            kwargs['to'] = self.rel.to
        else:
            kwargs['to'] = "%s.%s" % (self.rel.to._meta.app_label, self.rel.to._meta.object_name)
        # If swappable is True, then see if we're actually pointing to the target
        # of a swap.
        swappable_setting = self.swappable_setting
        if swappable_setting is not None:
            # If it's already a settings reference, error
            if hasattr(kwargs['to'], "setting_name"):
                if kwargs['to'].setting_name != swappable_setting:
                    raise ValueError(
                        "Cannot deconstruct a ForeignKey pointing to a model "
                        "that is swapped in place of more than one model (%s and %s)"
                        % (kwargs['to'].setting_name, swappable_setting)
                    )
            # Set it
            from django.db.migrations.writer import SettingsReference
            kwargs['to'] = SettingsReference(
                kwargs['to'],
                swappable_setting,
            )
        return name, path, args, kwargs