From c1cfec6b500c16200a4c2ef5676439c3cc987bc2 Mon Sep 17 00:00:00 2001
From: Hasan Ramezani <hasan.r67@gmail.com>
Date: Thu, 10 Oct 2019 21:13:21 +0200
Subject: [PATCH] [3.0.x] Fixed #30854 -- Fixed QuerySet.select_related() with
 multiple FilteredRelations.

Backport of 6a75cea76a98c08bf2e20d787be9b14c2cd94860 from master.
---
 django/db/models/sql/compiler.py | 10 ++++++----
 tests/filtered_relation/tests.py | 12 ++++++++++++
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/django/db/models/sql/compiler.py b/django/db/models/sql/compiler.py
index 5da862f716..e85e73de50 100644
--- a/django/db/models/sql/compiler.py
+++ b/django/db/models/sql/compiler.py
@@ -1,6 +1,7 @@
 import collections
 import re
 import warnings
+from functools import partial
 from itertools import chain
 
 from django.core.exceptions import EmptyResultSet, FieldError
@@ -902,6 +903,10 @@ class SQLCompiler:
                     select, model._meta, alias, cur_depth + 1,
                     next, restricted)
                 get_related_klass_infos(klass_info, next_klass_infos)
+
+            def remote_setter(name, obj, from_obj):
+                setattr(from_obj, name, obj)
+
             for name in list(requested):
                 # Filtered relations work only on the topmost level.
                 if cur_depth > 1:
@@ -917,15 +922,12 @@ class SQLCompiler:
                         # Set a reverse fk object when relation is non-empty.
                         if from_obj:
                             f.remote_field.set_cached_value(from_obj, obj)
-
-                    def remote_setter(obj, from_obj):
-                        setattr(from_obj, name, obj)
                     klass_info = {
                         'model': model,
                         'field': f,
                         'reverse': True,
                         'local_setter': local_setter,
-                        'remote_setter': remote_setter,
+                        'remote_setter': partial(remote_setter, name),
                         'from_parent': from_parent,
                     }
                     related_klass_infos.append(klass_info)
diff --git a/tests/filtered_relation/tests.py b/tests/filtered_relation/tests.py
index 52fe64dfa5..e80a94c164 100644
--- a/tests/filtered_relation/tests.py
+++ b/tests/filtered_relation/tests.py
@@ -50,6 +50,18 @@ class FilteredRelationTests(TestCase):
                 (self.author2, self.book3, self.editor_b, self.author2),
             ], lambda x: (x, x.book_join, x.book_join.editor, x.book_join.author))
 
+    def test_select_related_multiple(self):
+        qs = Book.objects.annotate(
+            author_join=FilteredRelation('author'),
+            editor_join=FilteredRelation('editor'),
+        ).select_related('author_join', 'editor_join').order_by('pk')
+        self.assertQuerysetEqual(qs, [
+            (self.book1, self.author1, self.editor_a),
+            (self.book2, self.author2, self.editor_b),
+            (self.book3, self.author2, self.editor_b),
+            (self.book4, self.author1, self.editor_a),
+        ], lambda x: (x, x.author_join, x.editor_join))
+
     def test_select_related_with_empty_relation(self):
         qs = Author.objects.annotate(
             book_join=FilteredRelation('book', condition=Q(pk=-1)),