Fixed #17530 - Fixture loading with deferred constraints broken for Postgres for fixtures from multiple dirs/files

Thanks to claudep for the review.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17372 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/regressiontests/fixtures_regress/fixtures_1/forward_ref_1.json

@@ -0,0 +1,10 @@
+[
+    {
+        "pk": 1,
+        "model": "fixtures_regress.book",
+        "fields": {
+            "name": "Cryptonomicon",
+            "author": 4
+        }
+    }
+]

tests/regressiontests/fixtures_regress/fixtures_2/forward_ref_2.json

@@ -0,0 +1,9 @@
+[
+    {
+        "pk": "4",
+        "model": "fixtures_regress.person",
+        "fields": {
+            "name": "Neal Stephenson"
+        }
+    }
+]

tests/regressiontests/fixtures_regress/tests.py

@@ -16,6 +16,7 @@ from django.db import transaction
 from django.db.models import signals
 from django.test import (TestCase, TransactionTestCase, skipIfDBFeature,
     skipUnlessDBFeature)
+from django.test.utils import override_settings
 
 from .models import (Animal, Stuff, Absolute, Parent, Child, Article, Widget,
     Store, Person, Book, NKChild, RefToNKChild, Circle1, Circle2, Circle3,
@@ -390,6 +391,25 @@ class TestFixtures(TestCase):
             stderr.getvalue().startswith('Problem installing fixture')
         )
 
+    _cur_dir = os.path.dirname(os.path.abspath(__file__))
+
+    @override_settings(FIXTURE_DIRS=[os.path.join(_cur_dir, 'fixtures_1'),
+                                     os.path.join(_cur_dir, 'fixtures_2')])
+    def test_loaddata_forward_refs_split_fixtures(self):
+        """
+        Regression for #17530 - should be able to cope with forward references
+        when the fixtures are not in the same files or directories.
+        """
+        management.call_command(
+            'loaddata',
+            'forward_ref_1.json',
+            'forward_ref_2.json',
+            verbosity=0,
+            commit=False
+        )
+        self.assertEqual(Book.objects.all()[0].id, 1)
+        self.assertEqual(Person.objects.all()[0].id, 4)
+
     def test_loaddata_no_fixture_specified(self):
         """
         Regression for #7043 - Error is quickly reported when no fixtures is provided in the command line.