""" Regression tests for a few FK bugs: #1578, #6886 """ from django.db import models # If ticket #1578 ever slips back in, these models will not be able to be # created (the field names being lower-cased versions of their opposite # classes is important here). class First(models.Model): second = models.IntegerField() class Second(models.Model): first = models.ForeignKey(First, related_name = 'the_first') # Protect against repetition of #1839, #2415 and #2536. class Third(models.Model): name = models.CharField(max_length=20) third = models.ForeignKey('self', null=True, related_name='child_set') class Parent(models.Model): name = models.CharField(max_length=20) bestchild = models.ForeignKey('Child', null=True, related_name='favored_by') class Child(models.Model): name = models.CharField(max_length=20) parent = models.ForeignKey(Parent) # Multiple paths to the same model (#7110, #7125) class Category(models.Model): name = models.CharField(max_length=20) def __unicode__(self): return self.name class Record(models.Model): category = models.ForeignKey(Category) class Relation(models.Model): left = models.ForeignKey(Record, related_name='left_set') right = models.ForeignKey(Record, related_name='right_set') def __unicode__(self): return u"%s - %s" % (self.left.category.name, self.right.category.name) __test__ = {'API_TESTS':""" >>> Third.objects.create(id='3', name='An example') >>> parent = Parent(name = 'fred') >>> parent.save() >>> Child.objects.create(name='bam-bam', parent=parent) # # 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 succeeds if field is null=True. >>> p.bestchild = None >>> p.bestchild is None 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 "": "Child.parent" must be a "Parent" instance. # Creation using keyword argument should cache the related object. >>> p = Parent.objects.get(name="Parent") >>> c = Child(parent=p) >>> c.parent is p True # Creation using keyword argument and unsaved related instance (#8070). >>> p = Parent() >>> c = Child(parent=p) >>> c.parent is p True # Creation using attname keyword argument and an id will cause the related # object to be fetched. >>> p = Parent.objects.get(name="Parent") >>> c = Child(parent_id=p.id) >>> c.parent is p False >>> c.parent == p True # # Test of multiple ForeignKeys to the same model (bug #7125). # >>> c1 = Category.objects.create(name='First') >>> c2 = Category.objects.create(name='Second') >>> c3 = Category.objects.create(name='Third') >>> r1 = Record.objects.create(category=c1) >>> r2 = Record.objects.create(category=c1) >>> r3 = Record.objects.create(category=c2) >>> r4 = Record.objects.create(category=c2) >>> r5 = Record.objects.create(category=c3) >>> r = Relation.objects.create(left=r1, right=r2) >>> r = Relation.objects.create(left=r3, right=r4) >>> r = Relation.objects.create(left=r1, right=r3) >>> r = Relation.objects.create(left=r5, right=r2) >>> r = Relation.objects.create(left=r3, right=r2) >>> Relation.objects.filter(left__category__name__in=['First'], right__category__name__in=['Second']) [] >>> Category.objects.filter(record__left_set__right__category__name='Second').order_by('name') [, ] """}