Implemented BaseDatabaseFeatures and changed all code to access it -- connection.features.foo instead of backend.foo

git-svn-id: http://code.djangoproject.com/svn/django/trunk@5974 bcc190cf-cafb-0310-a4f2-bffc1f526a37

10 files changed, 56 insertions, 78 deletions

diff --git a/django/db/backends/__init__.py b/django/db/backends/__init__.py
index 632dd36639..2415d453ce 100644
--- a/django/db/backends/__init__.py
+++ b/django/db/backends/__init__.py
@@ -39,6 +39,16 @@ class BaseDatabaseWrapper(local):
         from django.db.backends import util
         return util.CursorDebugWrapper(cursor, self)
 
+class BaseDatabaseFeatures(object):
+    allows_group_by_ordinal = True
+    allows_unique_and_pk = True
+    autoindexes_primary_keys = True
+    needs_datetime_string_cast = True
+    needs_upper_for_iops = False
+    supports_constraints = True
+    supports_tablespaces = False
+    uses_case_insensitive_names = False
+
 class BaseDatabaseOperations(object):
     """
     This class encapsulates all backend-specific differences, such as the way
diff --git a/django/db/backends/ado_mssql/base.py b/django/db/backends/ado_mssql/base.py
index fe7daaf765..60109b7226 100644
--- a/django/db/backends/ado_mssql/base.py
+++ b/django/db/backends/ado_mssql/base.py
@@ -4,7 +4,7 @@ ADO MSSQL database backend for Django.
 Requires adodbapi 2.0.1: http://adodbapi.sourceforge.net/
 """
 
-from django.db.backends import BaseDatabaseWrapper, BaseDatabaseOperations, util
+from django.db.backends import BaseDatabaseWrapper, BaseDatabaseFeatures, BaseDatabaseOperations, util
 try:
     import adodbapi as Database
 except ImportError, e:
@@ -48,6 +48,9 @@ def variantToPython(variant, adType):
     return res
 Database.convertVariantToPython = variantToPython
 
+class DatabaseFeatures(BaseDatabaseFeatures):
+    supports_tablespaces = True
+
 class DatabaseOperations(BaseDatabaseOperations):
     def date_extract_sql(self, lookup_type, field_name):
         return "DATEPART(%s, %s)" % (lookup_type, field_name)
@@ -79,6 +82,7 @@ class DatabaseOperations(BaseDatabaseOperations):
         return "ON %s" % self.quote_name(tablespace)
 
 class DatabaseWrapper(BaseDatabaseWrapper):
+    features = DatabaseFeatures()
     ops = DatabaseOperations()
 
     def _cursor(self, settings):
@@ -93,15 +97,6 @@ class DatabaseWrapper(BaseDatabaseWrapper):
             self.connection = Database.connect(conn_string)
         return self.connection.cursor()
 
-allows_group_by_ordinal = True
-allows_unique_and_pk = True
-autoindexes_primary_keys = True
-needs_datetime_string_cast = True
-needs_upper_for_iops = False
-supports_constraints = True
-supports_tablespaces = True
-uses_case_insensitive_names = False
-
 OPERATOR_MAPPING = {
     'exact': '= %s',
     'iexact': 'LIKE %s',
diff --git a/django/db/backends/dummy/base.py b/django/db/backends/dummy/base.py
index 94fa3e1c23..671c9d7291 100644
--- a/django/db/backends/dummy/base.py
+++ b/django/db/backends/dummy/base.py
@@ -21,12 +21,13 @@ class DatabaseError(Exception):
 class IntegrityError(DatabaseError):
     pass
 
-class DatabaseOperations(object):
+class ComplainOnGetattr(object):
     def __getattr__(self, *args, **kwargs):
         complain()
 
 class DatabaseWrapper(object):
-    ops = DatabaseOperations()
+    ops = ComplainOnGetattr()
+    features = ComplainOnGetattr()
     cursor = complain
     _commit = complain
     _rollback = ignore
@@ -37,7 +38,4 @@ class DatabaseWrapper(object):
     def close(self):
         pass # close()
 
-supports_constraints = False
-supports_tablespaces = False
-
 OPERATOR_MAPPING = {}
diff --git a/django/db/backends/mysql/base.py b/django/db/backends/mysql/base.py
index 1501508b4c..079bf36eb0 100644
--- a/django/db/backends/mysql/base.py
+++ b/django/db/backends/mysql/base.py
@@ -4,7 +4,7 @@ MySQL database backend for Django.
 Requires MySQLdb: http://sourceforge.net/projects/mysql-python
 """
 
-from django.db.backends import BaseDatabaseWrapper, BaseDatabaseOperations, util
+from django.db.backends import BaseDatabaseWrapper, BaseDatabaseFeatures, BaseDatabaseOperations, util
 try:
     import MySQLdb as Database
 except ImportError, e:
@@ -53,6 +53,9 @@ server_version_re = re.compile(r'(\d{1,2})\.(\d{1,2})\.(\d{1,2})')
 # standard util.CursorDebugWrapper can be used. Also, using sql_mode
 # TRADITIONAL will automatically cause most warnings to be treated as errors.
 
+class DatabaseFeatures(BaseDatabaseFeatures):
+    autoindexes_primary_keys = False
+
 class DatabaseOperations(BaseDatabaseOperations):
     def date_extract_sql(self, lookup_type, field_name):
         # http://dev.mysql.com/doc/mysql/en/date-and-time-functions.html
@@ -116,6 +119,7 @@ class DatabaseOperations(BaseDatabaseOperations):
             return []
 
 class DatabaseWrapper(BaseDatabaseWrapper):
+    features = DatabaseFeatures()
     ops = DatabaseOperations()
 
     def __init__(self, **kwargs):
@@ -175,15 +179,6 @@ class DatabaseWrapper(BaseDatabaseWrapper):
             self.server_version = tuple([int(x) for x in m.groups()])
         return self.server_version
 
-allows_group_by_ordinal = True
-allows_unique_and_pk = True
-autoindexes_primary_keys = False
-needs_datetime_string_cast = True     # MySQLdb requires a typecast for dates
-needs_upper_for_iops = False
-supports_constraints = True
-supports_tablespaces = False
-uses_case_insensitive_names = False
-
 OPERATOR_MAPPING = {
     'exact': '= %s',
     'iexact': 'LIKE %s',
diff --git a/django/db/backends/mysql_old/base.py b/django/db/backends/mysql_old/base.py
index 296a576e26..e4ff1c64b2 100644
--- a/django/db/backends/mysql_old/base.py
+++ b/django/db/backends/mysql_old/base.py
@@ -4,7 +4,7 @@ MySQL database backend for Django.
 Requires MySQLdb: http://sourceforge.net/projects/mysql-python
 """
 
-from django.db.backends import BaseDatabaseWrapper, BaseDatabaseOperations, util
+from django.db.backends import BaseDatabaseWrapper, BaseDatabaseFeatures, BaseDatabaseOperations, util
 from django.utils.encoding import force_unicode
 try:
     import MySQLdb as Database
@@ -63,6 +63,9 @@ class MysqlDebugWrapper:
         else:
             return getattr(self.cursor, attr)
 
+class DatabaseFeatures(BaseDatabaseFeatures):
+    autoindexes_primary_keys = False
+
 class DatabaseOperations(BaseDatabaseOperations):
     def date_extract_sql(self, lookup_type, field_name):
         # http://dev.mysql.com/doc/mysql/en/date-and-time-functions.html
@@ -126,6 +129,7 @@ class DatabaseOperations(BaseDatabaseOperations):
             return []
 
 class DatabaseWrapper(BaseDatabaseWrapper):
+    features = DatabaseFeatures()
     ops = DatabaseOperations()
 
     def __init__(self, **kwargs):
@@ -194,15 +198,6 @@ class DatabaseWrapper(BaseDatabaseWrapper):
             self.server_version = tuple([int(x) for x in m.groups()])
         return self.server_version
 
-allows_group_by_ordinal = True
-allows_unique_and_pk = True
-autoindexes_primary_keys = False
-needs_datetime_string_cast = True     # MySQLdb requires a typecast for dates
-needs_upper_for_iops = False
-supports_constraints = True
-supports_tablespaces = False
-uses_case_insensitive_names = False
-
 OPERATOR_MAPPING = {
     'exact': '= %s',
     'iexact': 'LIKE %s',
diff --git a/django/db/backends/oracle/base.py b/django/db/backends/oracle/base.py
index 842efde35c..f4f602ff0d 100644
--- a/django/db/backends/oracle/base.py
+++ b/django/db/backends/oracle/base.py
@@ -4,7 +4,7 @@ Oracle database backend for Django.
 Requires cx_Oracle: http://www.python.net/crew/atuining/cx_Oracle/
 """
 
-from django.db.backends import BaseDatabaseWrapper, BaseDatabaseOperations, util
+from django.db.backends import BaseDatabaseWrapper, BaseDatabaseFeatures, BaseDatabaseOperations, util
 from django.utils.datastructures import SortedDict
 from django.utils.encoding import smart_str, force_unicode
 import datetime
@@ -21,6 +21,14 @@ except ImportError, e:
 DatabaseError = Database.Error
 IntegrityError = Database.IntegrityError
 
+class DatabaseFeatures(BaseDatabaseFeatures):
+    allows_group_by_ordinal = False
+    allows_unique_and_pk = False        # Suppress UNIQUE/PK for Oracle (ORA-02259)
+    needs_datetime_string_cast = False
+    needs_upper_for_iops = True
+    supports_tablespaces = True
+    uses_case_insensitive_names = True
+
 class DatabaseOperations(BaseDatabaseOperations):
     def autoinc_sql(self, table):
         # To simulate auto-incrementing primary keys in Oracle, we have to
@@ -128,6 +136,7 @@ class DatabaseOperations(BaseDatabaseOperations):
         return "%sTABLESPACE %s" % ((inline and "USING INDEX " or ""), self.quote_name(tablespace))
 
 class DatabaseWrapper(BaseDatabaseWrapper):
+    features = DatabaseFeatures()
     ops = DatabaseOperations()
 
     def _valid_connection(self):
@@ -151,15 +160,6 @@ class DatabaseWrapper(BaseDatabaseWrapper):
         cursor.execute("ALTER SESSION SET NLS_TIMESTAMP_FORMAT = 'YYYY-MM-DD HH24:MI:SS.FF'")
         return cursor
 
-allows_group_by_ordinal = False
-allows_unique_and_pk = False        # Suppress UNIQUE/PK for Oracle (ORA-02259)
-autoindexes_primary_keys = True
-needs_datetime_string_cast = False
-needs_upper_for_iops = True
-supports_constraints = True
-supports_tablespaces = True
-uses_case_insensitive_names = True
-
 class FormatStylePlaceholderCursor(Database.Cursor):
     """
     Django uses "format" (e.g. '%s') style placeholders, but Oracle uses ":var"
diff --git a/django/db/backends/postgresql/base.py b/django/db/backends/postgresql/base.py
index 094670cbc6..755a34231c 100644
--- a/django/db/backends/postgresql/base.py
+++ b/django/db/backends/postgresql/base.py
@@ -5,7 +5,7 @@ Requires psycopg 1: http://initd.org/projects/psycopg1
 """
 
 from django.utils.encoding import smart_str, smart_unicode
-from django.db.backends import BaseDatabaseWrapper, util
+from django.db.backends import BaseDatabaseWrapper, BaseDatabaseFeatures, util
 from django.db.backends.postgresql.operations import DatabaseOperations
 try:
     import psycopg as Database
@@ -56,7 +56,11 @@ class UnicodeCursorWrapper(object):
         else:
             return getattr(self.cursor, attr)
 
+class DatabaseFeatures(BaseDatabaseFeatures):
+    pass # This backend uses all the defaults.
+
 class DatabaseWrapper(BaseDatabaseWrapper):
+    features = DatabaseFeatures()
     ops = DatabaseOperations()
 
     def _cursor(self, settings):
@@ -87,15 +91,6 @@ class DatabaseWrapper(BaseDatabaseWrapper):
             self.ops.postgres_version = [int(val) for val in cursor.fetchone()[0].split()[1].split('.')]
         return cursor
 
-allows_group_by_ordinal = True
-allows_unique_and_pk = True
-autoindexes_primary_keys = True
-needs_datetime_string_cast = True
-needs_upper_for_iops = False
-supports_constraints = True
-supports_tablespaces = False
-uses_case_insensitive_names = False
-
 def typecast_string(s):
     """
     Cast all returned strings to unicode strings.
diff --git a/django/db/backends/postgresql_psycopg2/base.py b/django/db/backends/postgresql_psycopg2/base.py
index 87b41877a6..0bcfd46ac4 100644
--- a/django/db/backends/postgresql_psycopg2/base.py
+++ b/django/db/backends/postgresql_psycopg2/base.py
@@ -4,7 +4,7 @@ PostgreSQL database backend for Django.
 Requires psycopg 2: http://initd.org/projects/psycopg2
 """
 
-from django.db.backends import BaseDatabaseWrapper
+from django.db.backends import BaseDatabaseWrapper, BaseDatabaseFeatures
 from django.db.backends.postgresql.operations import DatabaseOperations
 try:
     import psycopg2 as Database
@@ -18,7 +18,11 @@ IntegrityError = Database.IntegrityError
 
 psycopg2.extensions.register_type(psycopg2.extensions.UNICODE)
 
+class DatabaseFeatures(BaseDatabaseFeatures):
+    needs_datetime_string_cast = False
+
 class DatabaseWrapper(BaseDatabaseWrapper):
+    features = DatabaseFeatures()
     ops = DatabaseOperations()
 
     def _cursor(self, settings):
@@ -49,15 +53,6 @@ class DatabaseWrapper(BaseDatabaseWrapper):
             self.ops.postgres_version = [int(val) for val in cursor.fetchone()[0].split()[1].split('.')]
         return cursor
 
-allows_group_by_ordinal = True
-allows_unique_and_pk = True
-autoindexes_primary_keys = True
-needs_datetime_string_cast = False
-needs_upper_for_iops = False
-supports_constraints = True
-supports_tablespaces = False
-uses_case_insensitive_names = False
-
 OPERATOR_MAPPING = {
     'exact': '= %s',
     'iexact': 'ILIKE %s',
diff --git a/django/db/backends/sqlite3/base.py b/django/db/backends/sqlite3/base.py
index 96f88dfa17..2ffdefa73e 100644
--- a/django/db/backends/sqlite3/base.py
+++ b/django/db/backends/sqlite3/base.py
@@ -2,7 +2,7 @@
 SQLite3 backend for django.  Requires pysqlite2 (http://pysqlite.org/).
 """
 
-from django.db.backends import BaseDatabaseWrapper, BaseDatabaseOperations, util
+from django.db.backends import BaseDatabaseWrapper, BaseDatabaseFeatures, BaseDatabaseOperations, util
 try:
     try:
         from sqlite3 import dbapi2 as Database
@@ -34,6 +34,9 @@ Database.register_converter("TIMESTAMP", util.typecast_timestamp)
 Database.register_converter("decimal", util.typecast_decimal)
 Database.register_adapter(decimal.Decimal, util.rev_typecast_decimal)
 
+class DatabaseFeatures(BaseDatabaseFeatures):
+    supports_constraints = False
+
 class DatabaseOperations(BaseDatabaseOperations):
     def date_extract_sql(self, lookup_type, field_name):
         # sqlite doesn't support extract, so we fake it with the user-defined
@@ -70,6 +73,7 @@ class DatabaseOperations(BaseDatabaseOperations):
         return sql
 
 class DatabaseWrapper(BaseDatabaseWrapper):
+    features = DatabaseFeatures()
     ops = DatabaseOperations()
 
     def _cursor(self, settings):
@@ -111,15 +115,6 @@ class SQLiteCursorWrapper(Database.Cursor):
     def convert_query(self, query, num_params):
         return query % tuple("?" * num_params)
 
-allows_group_by_ordinal = True
-allows_unique_and_pk = True
-autoindexes_primary_keys = True
-needs_datetime_string_cast = True
-needs_upper_for_iops = False
-supports_constraints = False
-supports_tablespaces = False
-uses_case_insensitive_names = False
-
 def _sqlite_extract(lookup_type, dt):
     try:
         dt = util.typecast_timestamp(dt)
diff --git a/django/db/models/query.py b/django/db/models/query.py
index 8cf4510622..767942c6a5 100644
--- a/django/db/models/query.py
+++ b/django/db/models/query.py
@@ -651,7 +651,7 @@ class DateQuerySet(QuerySet):
         table_name = qn(self.model._meta.db_table)
         field_name = qn(self._field.column)
 
-        if backend.allows_group_by_ordinal:
+        if connection.features.allows_group_by_ordinal:
             group_by = '1'
         else:
             group_by = connection.ops.date_trunc_sql(self._kind, '%s.%s' % (table_name, field_name))
@@ -663,7 +663,7 @@ class DateQuerySet(QuerySet):
         cursor.execute(sql, params)
 
         has_resolve_columns = hasattr(self, 'resolve_columns')
-        needs_datetime_string_cast = backend.needs_datetime_string_cast
+        needs_datetime_string_cast = connection.features.needs_datetime_string_cast
         dates = []
         # It would be better to use self._field here instead of DateTimeField(),
         # but in Oracle that will result in a list of datetime.date instead of
@@ -796,7 +796,7 @@ def get_where_clause(lookup_type, table_prefix, field_name, value, db_type):
     else:
         field_cast_sql = '%s%s'
     field_sql = field_cast_sql % (table_prefix, field_name)
-    if lookup_type in ('iexact', 'icontains', 'istartswith', 'iendswith') and backend.needs_upper_for_iops:
+    if lookup_type in ('iexact', 'icontains', 'istartswith', 'iendswith') and connection.features.needs_upper_for_iops:
         format = 'UPPER(%s) %s'
     else:
         format = '%s %s'