generics.py 文件源码

def get_object(self):
        query = self.filter_query(self.get_query())

        # If query joins more than one table and you need to base the lookup on something besides
        # an id field on the self.model, you can provide an alternative lookup as tuple of the model class
        # and a string of the column name.

        if isinstance(self.lookup_field, str):
            lookup_col = getattr(self.model, self.lookup_field)
            lookup_val = self.lookup_url_kwargs[self.lookup_field]
        else:
            assert isinstance(self.lookup_field, tuple), (
                "'{}' `lookup_field` attribute should be a string or a tuple of (<model class>, `column`) "
                .format(self.__class__.__name__)
            )

            lookup_col = getattr(self.lookup_field[0], self.lookup_field[1])
            lookup_val = self.lookup_url_kwargs[self.lookup_field[1]]

        try:
            instance = query.filter(lookup_col == lookup_val).one()
        except NoResultFound:
            raise HTTPNotFound()

        # May raise HTTPForbidden
        self.check_object_permissions(self.request, instance)

        return instance