From 6cd37e0a1ffff06517a62c1cb0009825c551e31c Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Mon, 8 Jun 2009 04:50:24 +0000
Subject: [PATCH] Fixed #10785 -- Corrected a case for foreign key lookup where
 the related object is a custom primary key. Thanks to Alex Gaynor for the
 patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10952 bcc190cf-cafb-0310-a4f2-bffc1f526a37
---
 django/db/models/fields/related.py   | 14 ++++----
 tests/modeltests/custom_pk/fields.py | 54 ++++++++++++++++++++++++++++
 tests/modeltests/custom_pk/models.py | 27 ++++++++++++++
 3 files changed, 88 insertions(+), 7 deletions(-)
 create mode 100644 tests/modeltests/custom_pk/fields.py

diff --git a/django/db/models/fields/related.py b/django/db/models/fields/related.py
index 419695b74b..78019f2bd1 100644
--- a/django/db/models/fields/related.py
+++ b/django/db/models/fields/related.py
@@ -132,12 +132,13 @@ class RelatedField(object):
                     v, field = getattr(v, v._meta.pk.name), v._meta.pk
             except AttributeError:
                 pass
-            if field:
-                if lookup_type in ('range', 'in'):
-                    v = [v]
-                v = field.get_db_prep_lookup(lookup_type, v)
-                if isinstance(v, list):
-                    v = v[0]
+            if not field:
+                field = self.rel.get_related_field()
+            if lookup_type in ('range', 'in'):
+                v = [v]
+            v = field.get_db_prep_lookup(lookup_type, v)
+            if isinstance(v, list):
+                v = v[0]
             return v
 
         if hasattr(value, 'as_sql') or hasattr(value, '_as_sql'):
@@ -958,4 +959,3 @@ class ManyToManyField(RelatedField, Field):
         # A ManyToManyField is not represented by a single column,
         # so return None.
         return None
-
diff --git a/tests/modeltests/custom_pk/fields.py b/tests/modeltests/custom_pk/fields.py
new file mode 100644
index 0000000000..319e42f974
--- /dev/null
+++ b/tests/modeltests/custom_pk/fields.py
@@ -0,0 +1,54 @@
+import random
+import string
+
+from django.db import models
+
+class MyWrapper(object):
+    def __init__(self, value):
+        self.value = value
+
+    def __repr__(self):
+        return "<%s: %s>" % (self.__class__.__name__, self.value)
+
+    def __unicode__(self):
+        return self.value
+
+    def __eq__(self, other):
+        if isinstance(other, self.__class__):
+            return self.value == other.value
+        return self.value == other
+
+class MyAutoField(models.CharField):
+    __metaclass__ = models.SubfieldBase
+
+    def __init__(self, *args, **kwargs):
+        kwargs['max_length'] = 10
+        super(MyAutoField, self).__init__(*args, **kwargs)
+
+    def pre_save(self, instance, add):
+        value = getattr(instance, self.attname, None)
+        if not value:
+            value = MyWrapper(''.join(random.sample(string.lowercase, 10)))
+            setattr(instance, self.attname, value)
+        return value
+
+    def to_python(self, value):
+        if not value:
+            return
+        if not isinstance(value, MyWrapper):
+            value = MyWrapper(value)
+        return value
+
+    def get_db_prep_save(self, value):
+        if not value:
+            return
+        if isinstance(value, MyWrapper):
+            return unicode(value)
+        return value
+
+    def get_db_prep_value(self, value):
+        if not value:
+            return
+        if isinstance(value, MyWrapper):
+            return unicode(value)
+        return value
diff --git a/tests/modeltests/custom_pk/models.py b/tests/modeltests/custom_pk/models.py
index 091f7f32b4..b1d0cb37d0 100644
--- a/tests/modeltests/custom_pk/models.py
+++ b/tests/modeltests/custom_pk/models.py
@@ -9,6 +9,8 @@ this behavior by explicitly adding ``primary_key=True`` to a field.
 from django.conf import settings
 from django.db import models, transaction, IntegrityError
 
+from fields import MyAutoField
+
 class Employee(models.Model):
     employee_code = models.IntegerField(primary_key=True, db_column = 'code')
     first_name = models.CharField(max_length=20)
@@ -28,6 +30,16 @@ class Business(models.Model):
     def __unicode__(self):
         return self.name
 
+class Bar(models.Model):
+    id = MyAutoField(primary_key=True, db_index=True)
+
+    def __unicode__(self):
+        return repr(self.pk)
+
+
+class Foo(models.Model):
+    bar = models.ForeignKey(Bar)
+
 __test__ = {'API_TESTS':"""
 >>> dan = Employee(employee_code=123, first_name='Dan', last_name='Jones')
 >>> dan.save()
@@ -121,6 +133,21 @@ DoesNotExist: Employee matching query does not exist.
 ...        print "Fail with %s" % type(e)
 Pass
 
+# Regression for #10785 -- Custom fields can be used for primary keys.
+>>> new_bar = Bar.objects.create()
+>>> new_foo = Foo.objects.create(bar=new_bar)
+>>> f = Foo.objects.get(bar=new_bar.pk)
+>>> f == new_foo
+True
+>>> f.bar == new_bar
+True
+
+>>> f = Foo.objects.get(bar=new_bar)
+>>> f == new_foo
+True
+>>> f.bar == new_bar
+True
+
 """}
 
 # SQLite lets objects be saved with an empty primary key, even though an