[1.2.X] Fixed #14223 -- Extended unification of exception raised in presence of integrity constraint violations.

The unification had been introduced in r12352 and native backend exceptions still
slipped through in cases that end in connection.commit() call. Thanks Alex,
Jacob and Carl for reviewing.

Backport of [14320] from trunk

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@14321 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/backends/postgresql/base.py

@@ -150,6 +150,13 @@ class DatabaseWrapper(BaseDatabaseWrapper):
             cursor.execute("SET client_encoding to 'UNICODE'")
         return UnicodeCursorWrapper(cursor, 'utf-8')
 
+    def _commit(self):
+        if self.connection is not None:
+            try:
+                return self.connection.commit()
+            except Database.IntegrityError, e:
+                raise utils.IntegrityError, utils.IntegrityError(*tuple(e)), sys.exc_info()[2]
+
 def typecast_string(s):
     """
     Cast all returned strings to unicode strings.

django/db/backends/postgresql_psycopg2/base.py

@@ -189,3 +189,10 @@ class DatabaseWrapper(BaseDatabaseWrapper):
         finally:
             self.isolation_level = level
             self.features.uses_savepoints = bool(level)
+
+    def _commit(self):
+        if self.connection is not None:
+            try:
+                return self.connection.commit()
+            except Database.IntegrityError, e:
+                raise utils.IntegrityError, utils.IntegrityError(*tuple(e)), sys.exc_info()[2]

tests/regressiontests/backends/models.py

@@ -1,5 +1,4 @@
 from django.db import models
-from django.db import connection
 
 class Square(models.Model):
     root = models.IntegerField()
@@ -21,3 +20,18 @@ class SchoolClass(models.Model):
     last_updated = models.DateTimeField()
 
 
+class Reporter(models.Model):
+    first_name = models.CharField(max_length=30)
+    last_name = models.CharField(max_length=30)
+
+    def __unicode__(self):
+        return u"%s %s" % (self.first_name, self.last_name)
+
+
+class Article(models.Model):
+    headline = models.CharField(max_length=100)
+    pub_date = models.DateField()
+    reporter = models.ForeignKey(Reporter)
+
+    def __unicode__(self):
+        return self.headline

tests/regressiontests/backends/tests.py

@@ -1,13 +1,15 @@
 # -*- coding: utf-8 -*-
 # Unit and doctests for specific database backends.
 import datetime
-import models
 import unittest
-from django.db import backend, connection, DEFAULT_DB_ALIAS
+
+from django.conf import settings
+from django.db import backend, connection, DEFAULT_DB_ALIAS, IntegrityError
 from django.db.backends.signals import connection_created
 from django.db.backends.postgresql import version as pg_version
-from django.conf import settings
-from django.test import TestCase
+from django.test import TestCase, TransactionTestCase
+
+import models
 
 class Callproc(unittest.TestCase):
 
@@ -141,6 +143,46 @@ class BackendTestCase(TestCase):
         cursor.executemany(query, [])
         self.assertEqual(models.Square.objects.count(), 11)
 
+
+# We don't make these tests conditional because that means we would need to
+# check and differentiate between:
+# * MySQL+InnoDB, MySQL+MYISAM (something we currently can't do).
+# * if sqlite3 (if/once we get #14204 fixed) has referential integrity turned
+#   on or not, something that would be controlled by runtime support and user
+#   preference.
+# verify if its type is django.database.db.IntegrityError.
+
+class FkConstraintsTests(TransactionTestCase):
+
+    def setUp(self):
+        # Create a Reporter.
+        self.r = models.Reporter.objects.create(first_name='John', last_name='Smith')
+
+    def test_integrity_checks_on_creation(self):
+        """
+        Try to create a model instance that violates a FK constraint. If it
+        fails it should fail with IntegrityError.
+        """
+        a = models.Article(headline="This is a test", pub_date=datetime.datetime(2005, 7, 27), reporter_id=30)
+        try:
+            a.save()
+        except IntegrityError:
+            pass
+
+    def test_integrity_checks_on_update(self):
+        """
+        Try to update a model instance introducing a FK constraint violation.
+        If it fails it should fail with IntegrityError.
+        """
+        # Create an Article.
+        models.Article.objects.create(headline="Test article", pub_date=datetime.datetime(2010, 9, 4), reporter=self.r)
+        # Retrive it from the DB
+        a = models.Article.objects.get(headline="Test article")
+        a.reporter_id = 30
+        try:
+            a.save()
+        except IntegrityError:
+            pass
     def test_unicode_fetches(self):
         #6254: fetchone, fetchmany, fetchall return strings as unicode objects
         qn = connection.ops.quote_name