Fixed #1142 -- Added multiple database support.

This monster of a patch is the result of Alex Gaynor's 2009 Google Summer of Code project.
Congratulations to Alex for a job well done.

Big thanks also go to:
 * Justin Bronn for keeping GIS in line with the changes,
 * Karen Tracey and Jani Tiainen for their help testing Oracle support
 * Brett Hoerner, Jon Loyens, and Craig Kimmerer for their feedback.
 * Malcolm Treddinick for his guidance during the GSoC submission process.
 * Simon Willison for driving the original design process
 * Cal Henderson for complaining about ponies he wanted.

... and everyone else too numerous to mention that helped to bring this feature into fruition.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@11952 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/modeltests/basic/models.py

@@ -16,7 +16,7 @@ try:
 except NameError:
     from django.utils.itercompat import sorted
 
-from django.db import models
+from django.db import models, DEFAULT_DB_ALIAS
 
 class Article(models.Model):
     headline = models.CharField(max_length=100, default='Default headline')
@@ -373,7 +373,7 @@ from django.conf import settings
 
 building_docs = getattr(settings, 'BUILDING_DOCS', False)
 
-if building_docs or settings.DATABASE_ENGINE == 'postgresql':
+if building_docs or settings.DATABASES[DEFAULT_DB_ALIAS]['ENGINE'] == 'django.db.backends.postgresql':
     __test__['API_TESTS'] += """
 # In PostgreSQL, microsecond-level precision is available.
 >>> a9 = Article(headline='Article 9', pub_date=datetime(2005, 7, 31, 12, 30, 45, 180))
@@ -382,7 +382,7 @@ if building_docs or settings.DATABASE_ENGINE == 'postgresql':
 datetime.datetime(2005, 7, 31, 12, 30, 45, 180)
 """
 
-if building_docs or settings.DATABASE_ENGINE == 'mysql':
+if building_docs or settings.DATABASES[DEFAULT_DB_ALIAS]['ENGINE'] == 'django.db.backends.mysql':
     __test__['API_TESTS'] += """
 # In MySQL, microsecond-level precision isn't available. You'll lose
 # microsecond-level precision once the data is saved.

tests/modeltests/custom_pk/models.py

@@ -7,7 +7,7 @@ this behavior by explicitly adding ``primary_key=True`` to a field.
 """
 
 from django.conf import settings
-from django.db import models, transaction, IntegrityError
+from django.db import models, transaction, IntegrityError, DEFAULT_DB_ALIAS
 
 from fields import MyAutoField
 
@@ -156,7 +156,7 @@ True
 # SQLite lets objects be saved with an empty primary key, even though an
 # integer is expected. So we can't check for an error being raised in that case
 # for SQLite. Remove it from the suite for this next bit.
-if settings.DATABASE_ENGINE != 'sqlite3':
+if settings.DATABASES[DEFAULT_DB_ALIAS]['ENGINE'] != 'django.db.backends.sqlite3':
     __test__["API_TESTS"] += """
 # The primary key must be specified, so an error is raised if you try to create
 # an object without it.

tests/modeltests/delete/models.py

@@ -171,9 +171,9 @@ True
 # temporarily replace the UpdateQuery class to verify that E.f is actually nulled out first
 >>> import django.db.models.sql
 >>> class LoggingUpdateQuery(django.db.models.sql.UpdateQuery):
-...     def clear_related(self, related_field, pk_list):
+...     def clear_related(self, related_field, pk_list, using):
 ...         print "CLEARING FIELD",related_field.name
-...         return super(LoggingUpdateQuery, self).clear_related(related_field, pk_list)
+...         return super(LoggingUpdateQuery, self).clear_related(related_field, pk_list, using)
 >>> original_class = django.db.models.sql.UpdateQuery
 >>> django.db.models.sql.UpdateQuery = LoggingUpdateQuery
 >>> e1.delete()

tests/modeltests/fixtures/fixtures/db_fixture_1.default.json

@@ -0,0 +1,10 @@
+[
+    {
+        "pk": "6",
+        "model": "fixtures.article",
+        "fields": {
+            "headline": "Who needs more than one database?",
+            "pub_date": "2006-06-16 14:00:00"
+        }
+    }
+]

tests/modeltests/fixtures/fixtures/db_fixture_3.nosuchdb.json

@@ -0,0 +1,10 @@
+[
+    {
+        "pk": "8",
+        "model": "fixtures.article",
+        "fields": {
+            "headline": "There is no spoon.",
+            "pub_date": "2006-06-16 14:00:00"
+        }
+    }
+]

tests/modeltests/fixtures/models.py

@@ -11,9 +11,10 @@ in the application directory, on in one of the directories named in the
 from django.contrib.auth.models import Permission
 from django.contrib.contenttypes import generic
 from django.contrib.contenttypes.models import ContentType
-from django.db import models
+from django.db import models, DEFAULT_DB_ALIAS
 from django.conf import settings
 
+
 class Category(models.Model):
     title = models.CharField(max_length=100)
     description = models.TextField()
@@ -200,7 +201,7 @@ __test__ = {'API_TESTS': """
 
 # Database flushing does not work on MySQL with the default storage engine
 # because it requires transaction support.
-if settings.DATABASE_ENGINE != 'mysql':
+if settings.DATABASES[DEFAULT_DB_ALIAS]['ENGINE'] != 'django.db.backends.mysql':
     __test__['API_TESTS'] += \
 """
 # Reset the database representation of this app. This will delete all data.
@@ -261,6 +262,41 @@ Multiple fixtures named 'fixture5' in '...fixtures'. Aborting.
 
 >>> management.call_command('flush', verbosity=0, interactive=False)
 
+# Load db fixtures 1 and 2. These will load using the 'default' database identifier implicitly
+>>> management.call_command('loaddata', 'db_fixture_1', verbosity=0)
+>>> management.call_command('loaddata', 'db_fixture_2', verbosity=0)
+>>> Article.objects.all()
+[<Article: Who needs more than one database?>, <Article: Who needs to use compressed data?>, <Article: Python program becomes self aware>]
+
+>>> management.call_command('flush', verbosity=0, interactive=False)
+
+# Load db fixtures 1 and 2. These will load using the 'default' database identifier explicitly
+>>> management.call_command('loaddata', 'db_fixture_1', verbosity=0, using='default')
+>>> management.call_command('loaddata', 'db_fixture_2', verbosity=0, using='default')
+>>> Article.objects.all()
+[<Article: Who needs more than one database?>, <Article: Who needs to use compressed data?>, <Article: Python program becomes self aware>]
+
+>>> management.call_command('flush', verbosity=0, interactive=False)
+
+# Try to load db fixture 3. This won't load because the database identifier doesn't match
+>>> management.call_command('loaddata', 'db_fixture_3', verbosity=0)
+>>> Article.objects.all()
+[<Article: Python program becomes self aware>]
+
+>>> management.call_command('loaddata', 'db_fixture_3', verbosity=0, using='default')
+>>> Article.objects.all()
+[<Article: Python program becomes self aware>]
+
+>>> management.call_command('flush', verbosity=0, interactive=False)
+
+# Try to load fixture 1, but this time, exclude the 'fixtures' app.
+>>> management.call_command('loaddata', 'fixture1', verbosity=0, exclude='fixtures')
+>>> Article.objects.all()
+[<Article: Python program becomes self aware>]
+
+>>> Category.objects.all()
+[]
+
 # Load back in fixture 1, we need the articles from it
 >>> management.call_command('loaddata', 'fixture1', verbosity=0)
 

tests/modeltests/lookup/models.py

@@ -4,7 +4,7 @@
 This demonstrates features of the database API.
 """
 
-from django.db import models
+from django.db import models, DEFAULT_DB_ALIAS
 from django.conf import settings
 
 class Article(models.Model):
@@ -43,7 +43,9 @@ False
 True
 """}
 
-if settings.DATABASE_ENGINE in ('postgresql', 'postgresql_pysycopg2'):
+if settings.DATABASES[DEFAULT_DB_ALIAS]['ENGINE'] in (
+        'django.db.backends.postgresql',
+        'django.db.backends.postgresql_pysycopg2'):
     __test__['API_TESTS'] += r"""
 # text matching tests for PostgreSQL 8.3
 >>> Article.objects.filter(id__iexact='1')
@@ -405,7 +407,7 @@ FieldError: Join on field 'headline' not permitted. Did you misspell 'starts' fo
 """
 
 
-if settings.DATABASE_ENGINE != 'mysql':
+if settings.DATABASES[DEFAULT_DB_ALIAS]['ENGINE'] != 'django.db.backends.mysql':
     __test__['API_TESTS'] += r"""
 # grouping and backreferences
 >>> Article.objects.filter(headline__regex=r'b(.).*b\1')

tests/modeltests/many_to_one/models.py

@@ -157,7 +157,7 @@ False
 
 # The underlying query only makes one join when a related table is referenced twice.
 >>> queryset = Article.objects.filter(reporter__first_name__exact='John', reporter__last_name__exact='Smith')
->>> sql = queryset.query.as_sql()[0]
+>>> sql = queryset.query.get_compiler(queryset.db).as_sql()[0]
 >>> sql.count('INNER JOIN')
 1
 

tests/modeltests/proxy_models/models.py

@@ -166,12 +166,13 @@ class ProxyImprovement(Improvement):
 __test__ = {'API_TESTS' : """
 # The MyPerson model should be generating the same database queries as the
 # Person model (when the same manager is used in each case).
->>> MyPerson.other.all().query.as_sql() == Person.objects.order_by("name").query.as_sql()
+>>> from django.db import DEFAULT_DB_ALIAS
+>>> MyPerson.other.all().query.get_compiler(DEFAULT_DB_ALIAS).as_sql() == Person.objects.order_by("name").query.get_compiler(DEFAULT_DB_ALIAS).as_sql()
 True
 
 # The StatusPerson models should have its own table (it's using ORM-level
 # inheritance).
->>> StatusPerson.objects.all().query.as_sql() == Person.objects.all().query.as_sql()
+>>> StatusPerson.objects.all().query.get_compiler(DEFAULT_DB_ALIAS).as_sql() == Person.objects.all().query.get_compiler(DEFAULT_DB_ALIAS).as_sql()
 False
 
 # Creating a Person makes them accessible through the MyPerson proxy.

tests/modeltests/raw_query/tests.py

@@ -10,7 +10,7 @@ class RawQueryTests(TestCase):
         """
         Execute the passed query against the passed model and check the output
         """
-        results = list(model.objects.raw(query=query, params=params, translations=translations))
+        results = list(model.objects.raw(query, params=params, translations=translations))
         self.assertProcessed(results, expected_results, expected_annotations)
         self.assertAnnotations(results, expected_annotations)
 
@@ -111,7 +111,7 @@ class RawQueryTests(TestCase):
         query = "SELECT * FROM raw_query_author WHERE first_name = %s"
         author = Author.objects.all()[2]
         params = [author.first_name]
-        results = list(Author.objects.raw(query=query, params=params))
+        results = list(Author.objects.raw(query, params=params))
         self.assertProcessed(results, [author])
         self.assertNoAnnotations(results)
         self.assertEqual(len(results), 1)

tests/modeltests/serializers/models.py

@@ -149,8 +149,8 @@ __test__ = {'API_TESTS':"""
 # database since the data was serialized (we'll simulate that below).
 >>> for obj in serializers.deserialize("xml", xml):
 ...     print obj
-<DeserializedObject: Poker has no place on ESPN>
-<DeserializedObject: Time to reform copyright>
+<DeserializedObject: serializers.Article(pk=1)>
+<DeserializedObject: serializers.Article(pk=2)>
 
 # Deserializing data with different field values doesn't change anything in the
 # database until we call save():
@@ -183,8 +183,8 @@ __test__ = {'API_TESTS':"""
 >>> json = serializers.serialize("json", Article.objects.all())
 >>> for obj in serializers.deserialize("json", json):
 ...     print obj
-<DeserializedObject: Poker has no place on television>
-<DeserializedObject: Time to reform copyright>
+<DeserializedObject: serializers.Article(pk=1)>
+<DeserializedObject: serializers.Article(pk=2)>
 
 >>> json = json.replace("Poker has no place on television", "Just kidding; I love TV poker")
 >>> for obj in serializers.deserialize("json", json):
@@ -205,7 +205,7 @@ __test__ = {'API_TESTS':"""
 
 >>> for obj in serializers.deserialize("json", json):
 ...     print obj
-<DeserializedObject: Profile of Joe>
+<DeserializedObject: serializers.AuthorProfile(pk=1)>
 
 # Objects ids can be referenced before they are defined in the serialization data
 # However, the deserialization process will need to be contained within a transaction
@@ -275,7 +275,7 @@ None
 
 >>> obj = list(serializers.deserialize("json", serialized))[0]
 >>> print obj
-<DeserializedObject: Soslan Djanaev (1) playing for Spartak Moskva>
+<DeserializedObject: serializers.Player(pk=1)>
 
 """}
 
@@ -310,8 +310,8 @@ try:
 >>> obs = list(serializers.deserialize("yaml", serialized))
 >>> for i in obs:
 ...     print i
-<DeserializedObject: Just kidding; I love TV poker>
-<DeserializedObject: Time to reform copyright>
+<DeserializedObject: serializers.Article(pk=1)>
+<DeserializedObject: serializers.Article(pk=2)>
 
 # Custom field with non trivial to string convertion value with YAML serializer
 
@@ -324,7 +324,7 @@ try:
 >>> serialized = serializers.serialize("yaml", Player.objects.all())
 >>> obj = list(serializers.deserialize("yaml", serialized))[0]
 >>> print obj
-<DeserializedObject: Soslan Djanaev (1) playing for Spartak Moskva>
+<DeserializedObject: serializers.Player(pk=1)>
 
 
 """

tests/modeltests/transactions/models.py

@@ -7,7 +7,7 @@ commit-on-success behavior. Alternatively, you can manage the transaction
 manually.
 """
 
-from django.db import models
+from django.db import models, DEFAULT_DB_ALIAS
 
 class Reporter(models.Model):
     first_name = models.CharField(max_length=30)
@@ -28,7 +28,7 @@ from django.conf import settings
 
 building_docs = getattr(settings, 'BUILDING_DOCS', False)
 
-if building_docs or settings.DATABASE_ENGINE != 'mysql':
+if building_docs or settings.DATABASES[DEFAULT_DB_ALIAS]['ENGINE'] != 'django.db.backends.mysql':
     __test__['API_TESTS'] += """
 # the default behavior is to autocommit after each save() action
 >>> def create_a_reporter_then_fail(first, last):