Deep conditions in FilteredRelation raise ProgrammingError if annotation reused

[Jacob Walls]

I was debugging a query that failed like this:

psycopg.errors.UndefinedTable: missing FROM-clause entry for table "book_editor"
LINE 1: ...r" LEFT OUTER JOIN "filtered_relation_editor" ON (book_edito...

#34229 seems related. Here, the key is using a deeper condition relation (book__editor) than the filtered relation (book) and then reusing that attempted annotation in another annotate().

Failing unit test. The test right above ​asserts that a ValueError is raised in a similar situation, so maybe this test should do that also? See comment:1

tests/filtered_relation/tests.py

@@ -668 +668 @@
                 ),
             )
 
+    def test_condition_deeper_relation_name_reused_annotation(self):
+        qs = Author.objects.annotate(
+            book_editor=FilteredRelation(
+                "book",
+                condition=Q(book__editor__name="b"),
+            ),
+        ).annotate(reused_annotation=F("book_editor"))
+        self.assertEqual(qs.count(), 2)
+
     def test_with_empty_relation_name_error(self):
         with self.assertRaisesMessage(ValueError, "relation_name cannot be empty."):
             FilteredRelation("", condition=Q(blank=""))

[Sarah Boyce]

Thank you for the test case!

[Jacob Walls]

Here's a better unit test that asserts ValueError is raised. This passes if you adjust the lookup to add an explicit __exact, so hopefully the solve is to just account for implicit exact when counting relation depths:

tests/filtered_relation/tests.py

@@ -668 +668 @@
                 ),
             )
 
+    def test_condition_deeper_relation_name_implicit_exact(self):
+        msg = (
+            "FilteredRelation's condition doesn't support nested relations "
+            "deeper than the relation_name (got "
+            "'book__editor__name' for 'book')."
+        )
+        with self.assertRaisesMessage(ValueError, msg):
+            Author.objects.annotate(
+                book_editor=FilteredRelation(
+                    "book",
+                    condition=Q(book__editor__name="b"),
+                ),
+            )
+
     def test_with_empty_relation_name_error(self):
         with self.assertRaisesMessage(ValueError, "relation_name cannot be empty."):
             FilteredRelation("", condition=Q(blank=""))