query.py 文件源码

def _process_aggregate_args(self, args, kwargs):
        """for aggregate and annotate kwargs: allow ModelX___field syntax for kwargs, forbid it for args.
        Modifies kwargs if needed (these are Aggregate objects, we translate the lookup member variable)"""

        def patch_lookup_lt_18(a):
            a.lookup = translate_polymorphic_field_path(self.model, a.lookup)


        def patch_lookup_gte_18(a):
            # With Django > 1.8, the field on which the aggregate operates is
            # stored inside a complex query expression.
            if isinstance(a, Q):
                translate_polymorphic_Q_object(self.model, a)
            elif hasattr(a, 'get_source_expressions'):
                for source_expression in a.get_source_expressions():
                    patch_lookup_gte_18(source_expression)
            else:
                a.name = translate_polymorphic_field_path(self.model, a.name)

        ___lookup_assert_msg = 'PolymorphicModel: annotate()/aggregate(): ___ model lookup supported for keyword arguments only'
        def test___lookup_for_args_lt_18(a):
            assert '___' not in a.lookup, ___lookup_assert_msg

        def test___lookup_for_args_gte_18(a):
            """ *args might be complex expressions too in django 1.8 so
            the testing for a '___' is rather complex on this one """
            if isinstance(a, Q):
                def tree_node_test___lookup(my_model, node):
                    " process all children of this Q node "
                    for i in range(len(node.children)):
                        child = node.children[i]

                        if type(child) == tuple:
                            # this Q object child is a tuple => a kwarg like Q( instance_of=ModelB )
                            assert '___' not in child[0], ___lookup_assert_msg
                        else:
                            # this Q object child is another Q object, recursively process this as well
                            tree_node_test___lookup(my_model, child)

                tree_node_test___lookup(self.model, a)
            elif hasattr(a, 'get_source_expressions'):
                for source_expression in a.get_source_expressions():
                    test___lookup_for_args_gte_18(source_expression)
            else:
                assert '___' not in a.name, ___lookup_assert_msg

        for a in args:
            test___lookup = test___lookup_for_args_lt_18 if django.VERSION < (1, 8) else test___lookup_for_args_gte_18
            test___lookup(a)
        for a in six.itervalues(kwargs):
            patch_lookup = patch_lookup_lt_18 if django.VERSION < (1, 8) else patch_lookup_gte_18
            patch_lookup(a)