related.py 文件源码

def resolve_related_fields(self):
        if len(self.from_fields) < 1 or len(self.from_fields) != len(self.to_fields):
            raise ValueError('Foreign Object from and to fields must be the same non-zero length')
        if isinstance(self.remote_field.model, six.string_types):
            raise ValueError('Related model %r cannot be resolved' % self.remote_field.model)
        related_fields = []
        for index in range(len(self.from_fields)):
            from_field_name = self.from_fields[index]
            to_field_name = self.to_fields[index]
            from_field = (self if from_field_name == 'self'
                          else self.opts.get_field(from_field_name))
            to_field = (self.remote_field.model._meta.pk if to_field_name is None
                        else self.remote_field.model._meta.get_field(to_field_name))
            related_fields.append((from_field, to_field))
        return related_fields