From 59ac04a54dde3a489f7948b6e6d6170d74aa80c8 Mon Sep 17 00:00:00 2001
From: Malcolm Tredinnick <malcolm.tredinnick@gmail.com>
Date: Fri, 14 Mar 2008 11:46:26 +0000
Subject: [PATCH] queryset-refactor: Second part of select_related() fix.

Relations on the parent model can now be specified as part of the fields list.
Fixed #6761.


git-svn-id: http://code.djangoproject.com/svn/django/branches/queryset-refactor@7241 bcc190cf-cafb-0310-a4f2-bffc1f526a37
---
 django/db/models/sql/query.py                | 20 +++++++++---
 tests/modeltests/model_inheritance/models.py | 32 +++++++++++++++++---
 2 files changed, 43 insertions(+), 9 deletions(-)

diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index 77f3519516..6d36ac3e40 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -769,10 +769,10 @@ class Query(object):
             return
         if not opts:
             opts = self.get_meta()
-            root_alias = self.tables[0]
+            root_alias = self.get_initial_alias()
             self.select.extend(self.get_default_columns())
         if not used:
-            used = []
+            used = set()
 
         # Setup for the case when only particular related fields should be
         # included in the related selection.
@@ -783,14 +783,24 @@ class Query(object):
             else:
                 restricted = False
 
-        for f in opts.fields:
+        for f, model in opts.get_fields_with_model():
             if (not f.rel or (restricted and f.name not in requested) or
                     (not restricted and f.null) or f.rel.parent_link):
                 continue
             table = f.rel.to._meta.db_table
-            alias = self.join((root_alias, table, f.column,
+            if model:
+                int_opts = opts
+                alias = root_alias
+                for int_model in opts.get_base_chain(model):
+                    lhs_col = int_opts.parents[int_model].column
+                    int_opts = int_model._meta
+                    alias = self.join((alias, int_opts.db_table, lhs_col,
+                            int_opts.pk.column), exclusions=used)
+            else:
+                alias = root_alias
+            alias = self.join((alias, table, f.column,
                     f.rel.get_related_field().column), exclusions=used)
-            used.append(alias)
+            used.add(alias)
             self.select.extend([(alias, f2.column)
                     for f2 in f.rel.to._meta.fields])
             if restricted:
diff --git a/tests/modeltests/model_inheritance/models.py b/tests/modeltests/model_inheritance/models.py
index 3f13dabc72..4a8c00fb52 100644
--- a/tests/modeltests/model_inheritance/models.py
+++ b/tests/modeltests/model_inheritance/models.py
@@ -42,6 +42,12 @@ class Student(CommonInfo):
 # Multi-table inheritance
 #
 
+class Chef(models.Model):
+    name = models.CharField(max_length=50)
+
+    def __unicode__(self):
+        return u"%s the chef" % self.name
+
 class Place(models.Model):
     name = models.CharField(max_length=50)
     address = models.CharField(max_length=80)
@@ -59,6 +65,7 @@ class Rating(models.Model):
 class Restaurant(Place, Rating):
     serves_hot_dogs = models.BooleanField()
     serves_pizza = models.BooleanField()
+    chef = models.ForeignKey(Chef, null=True, blank=True)
 
     class Meta(Rating.Meta):
         db_table = 'my_restaurant'
@@ -136,7 +143,9 @@ Test constructor for Restaurant.
 >>> r.save()
 
 # Test the constructor for ItalianRestaurant.
->>> ir = ItalianRestaurant(name='Ristorante Miron', address='1234 W. Ash', serves_hot_dogs=False, serves_pizza=False, serves_gnocchi=True, rating=4)
+>>> c = Chef(name="Albert")
+>>> c.save()
+>>> ir = ItalianRestaurant(name='Ristorante Miron', address='1234 W. Ash', serves_hot_dogs=False, serves_pizza=False, serves_gnocchi=True, rating=4, chef=c)
 >>> ir.save()
 >>> ir.address = '1234 W. Elm'
 >>> ir.save()
@@ -144,9 +153,9 @@ Test constructor for Restaurant.
 # Make sure Restaurant and ItalianRestaurant have the right fields in the right
 # order.
 >>> [f.name for f in Restaurant._meta.fields]
-['id', 'name', 'address', 'place_ptr', 'rating', 'serves_hot_dogs', 'serves_pizza']
+['id', 'name', 'address', 'place_ptr', 'rating', 'serves_hot_dogs', 'serves_pizza', 'chef']
 >>> [f.name for f in ItalianRestaurant._meta.fields]
-['id', 'name', 'address', 'place_ptr', 'rating', 'serves_hot_dogs', 'serves_pizza', 'restaurant_ptr', 'serves_gnocchi']
+['id', 'name', 'address', 'place_ptr', 'rating', 'serves_hot_dogs', 'serves_pizza', 'chef', 'restaurant_ptr', 'serves_gnocchi']
 >>> Restaurant._meta.ordering
 ['-rating']
 
@@ -158,7 +167,7 @@ Test constructor for Restaurant.
 >>> Restaurant.objects.filter(supplier__name='foo')
 Traceback (most recent call last):
     ...
-FieldError: Cannot resolve keyword 'supplier' into field. Choices are: address, id, italianrestaurant, lot, name, place_ptr, provider, rating, serves_hot_dogs, serves_pizza
+FieldError: Cannot resolve keyword 'supplier' into field. Choices are: address, chef, id, italianrestaurant, lot, name, place_ptr, provider, rating, serves_hot_dogs, serves_pizza
 
 # Parent fields can be used directly in filters on the child model.
 >>> Restaurant.objects.filter(name='Demon Dogs')
@@ -240,4 +249,19 @@ u'Demon Puppies'
 >>> list(ItalianRestaurant.objects.values('name', 'rating')) == [d]
 True
 
+# select_related works with fields from the parent object as if they were a
+# normal part of the model.
+>>> from django import db
+>>> from django.conf import settings
+>>> settings.DEBUG = True
+>>> db.reset_queries()
+>>> ItalianRestaurant.objects.all()[0].chef
+<Chef: Albert the chef>
+>>> len(db.connection.queries)
+2
+>>> ItalianRestaurant.objects.select_related('chef')[0].chef
+<Chef: Albert the chef>
+>>> len(db.connection.queries)
+3
+
 """}