Changeset 7574

Timestamp:

06/04/08 19:39:32 (3 months ago)

Author:

jacob

Message:

Fixed #6886: Tightened up ForeignKey? and OneToOne? field assignment. Specifically:

• Raise a ValueError? if you try to assign the wrong type of object.
  
• Raise a ValueError? if you try to assign None to a field not specified with null=True.
  
• Cache the set value at set time instead of just at lookup time.
  

This is a slightly backwards-incompatible change; see BackwardsIncompatibleChanges for more details.

Files:

• django/trunk/django/db/models/fields/related.py (modified) (3 diffs)
• django/trunk/tests/modeltests/one_to_one/models.py (modified) (1 diff)
• django/trunk/tests/regressiontests/many_to_one_regress/models.py (modified) (2 diffs)
• django/trunk/tests/regressiontests/one_to_one_regress/models.py (modified) (1 diff)

django/trunk/django/db/models/fields/related.py

@@ -183 +183 @@
-        if instance is None:
-            raise AttributeError, "%s must be accessed via instance" % self.related.opts.object_name
+        
+        # The similarity of the code below to the code in 
+        # ReverseSingleRelatedObjectDescriptor is annoying, but there's a bunch
+        # of small differences that would make a common base class convoluted.
+        
+        # If null=True, we can assign null here, but otherwise the value needs
+        # to be an instance of the related class.
+        if value is None and self.related.field.null == False:
+            raise ValueError('Cannot assign None: "%s.%s" does not allow null values.' %
+                                (instance._meta.object_name, self.related.get_accessor_name()))
+        elif value is not None and not isinstance(value, self.related.model):
+            raise ValueError('Cannot assign "%r": "%s.%s" must be a "%s" instance.' %
+                                (value, instance._meta.object_name, 
+                                 self.related.get_accessor_name(), self.related.opts.object_name))
+        
-        # Set the value of the related field
-        setattr(value, self.related.field.rel.get_related_field().attname, instance)
-
-Clear the cache, if it exists
-try:
-    delattr(value, self.related.field.get_cache_name())
-except AttributeError:
-    pass
+Since we already know what the related object is, seed the related
+# object caches now, too. This avoids another db hit if you get the 
+# object you just set.
+setattr(instance, self.cache_name, value)
+setattr(value, self.related.field.get_cache_name(), instance)
-
-class ReverseSingleRelatedObjectDescriptor(object):
@@ -226 +241 @@
-        if instance is None:
-            raise AttributeError, "%s must be accessed via instance" % self._field.name
+        
+        # If null=True, we can assign null here, but otherwise the value needs
+        # to be an instance of the related class.
+        if value is None and self.field.null == False:
+            raise ValueError('Cannot assign None: "%s.%s" does not allow null values.' %
+                                (instance._meta.object_name, self.field.name))
+        elif value is not None and not isinstance(value, self.field.rel.to):
+            raise ValueError('Cannot assign "%r": "%s.%s" must be a "%s" instance.' %
+                                (value, instance._meta.object_name, 
+                                 self.field.name, self.field.rel.to._meta.object_name))
+        
-        # Set the value of the related field
-        try:
@@ -233 +259 @@
-        setattr(instance, self.field.attname, val)
-
-
-
-
-
-
+
+
+
+
-
-class ForeignRelatedObjectsDescriptor(object):

django/trunk/tests/modeltests/one_to_one/models.py

@@ -81 +81 @@
-<Place: Ace Hardware the place>
-
-
-
-
+
->>> p1.restaurant = r
->>> r.save()
->>> p1.restaurant
-<Restaurant: Demon Dogs the restaurant>

django/trunk/tests/regressiontests/many_to_one_regress/models.py

@@ +1 @@
+"""
+Regression tests for a few FK bugs: #1578, #6886
+"""
+
-from django.db import models
-
@@ -26 +30 @@
-
-__test__ = {'API_TESTS':"""
-AddManipulator().save(dict(id='3', name='An example', another=None)) 
+objects.create(id='3', name='An example')
-<Third: Third object>
->>> parent = Parent(name = 'fred')
->>> parent.save()
-AddManipulator().save(dict(name='bam-bam', parent=parent.id)
+objects.create(name='bam-bam', parent=parent
-<Child: Child object>
+
+#
+# Tests of ForeignKey assignment and the related-object cache (see #6886)
+#
+>>> p = Parent.objects.create(name="Parent")
+>>> c = Child.objects.create(name="Child", parent=p)
+
+# Look up the object again so that we get a "fresh" object
+>>> c = Child.objects.get(name="Child")
+>>> p = c.parent
+
+# Accessing the related object again returns the exactly same object
+>>> c.parent is p
+True
+
+# But if we kill the cache, we get a new object
+>>> del c._parent_cache
+>>> c.parent is p
+False
+
+# Assigning a new object results in that object getting cached immediately
+>>> p2 = Parent.objects.create(name="Parent 2")
+>>> c.parent = p2
+>>> c.parent is p2
+True
+
+# Assigning None fails: Child.parent is null=False
+>>> c.parent = None
+Traceback (most recent call last):
+    ...
+ValueError: Cannot assign None: "Child.parent" does not allow null values.
+
+# You also can't assign an object of the wrong type here
+>>> c.parent = First(id=1, second=1)
+Traceback (most recent call last):
+    ...
+ValueError: Cannot assign "<First: First object>": "Child.parent" must be a "Parent" instance.
+
-"""}

django/trunk/tests/regressiontests/one_to_one_regress/models.py

@@ -51 +51 @@
->>> p1.bar
-<Bar: Demon Dogs the bar>
+
+#
+# Regression test for #6886 (the related-object cache)
+# 
+
+# Look up the objects again so that we get "fresh" objects
+>>> p = Place.objects.get(name="Demon Dogs")
+>>> r = p.restaurant
+
+# Accessing the related object again returns the exactly same object
+>>> p.restaurant is r
+True
+
+# But if we kill the cache, we get a new object
+>>> del p._restaurant_cache
+>>> p.restaurant is r
+False
+
+# Reassigning the Restaurant object results in an immediate cache update
+# We can't use a new Restaurant because that'll violate one-to-one, but
+# with a new *instance* the is test below will fail if #6886 regresses.
+>>> r2 = Restaurant.objects.get(pk=r.pk)
+>>> p.restaurant = r2
+>>> p.restaurant is r2
+True
+
+# Assigning None fails: Place.restaurant is null=False
+>>> p.restaurant = None
+Traceback (most recent call last):
+    ...
+ValueError: Cannot assign None: "Place.restaurant" does not allow null values.
+
+# You also can't assign an object of the wrong type here
+>>> p.restaurant = p
+Traceback (most recent call last):
+    ...
+ValueError: Cannot assign "<Place: Demon Dogs the place>": "Place.restaurant" must be a "Restaurant" instance.
+
-"""}