Began implementing BaseDatabaseOperations class for every database backend. This…

Began implementing BaseDatabaseOperations class for every database backend. This class will be used to hold the database-specific methods that currently live at the module level in each backend. Only autoinc_sql() has been implemented so far.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@5950 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/management/sql.py

@@ -213,7 +213,7 @@ def sql_model_create(model, style, known_models=set()):
     Returns the SQL required to create a single model, as a tuple of:
         (list_of_sql, pending_references_dict)
     """
-    from django.db import backend, models
+    from django.db import backend, connection, models
 
     opts = model._meta
     final_output = []
@@ -267,9 +267,9 @@ def sql_model_create(model, style, known_models=set()):
     full_statement.append(';')
     final_output.append('\n'.join(full_statement))
 
-    if opts.has_auto_field and hasattr(backend, 'get_autoinc_sql'):
-        # Add any extra SQL needed to support auto-incrementing primary keys
-        autoinc_sql = backend.get_autoinc_sql(opts.db_table)
+    if opts.has_auto_field:
+        # Add any extra SQL needed to support auto-incrementing primary keys.
+        autoinc_sql = connection.ops.autoinc_sql(opts.db_table)
         if autoinc_sql:
             for stmt in autoinc_sql:
                 final_output.append(stmt)

django/db/backends/__init__.py

@@ -6,6 +6,10 @@ except ImportError:
     from django.utils._threading_local import local
 
 class BaseDatabaseWrapper(local):
+    """
+    Represents a database connection.
+    """
+    ops = None
     def __init__(self, **kwargs):
         self.connection = None
         self.queries = []
@@ -34,3 +38,18 @@ class BaseDatabaseWrapper(local):
     def make_debug_cursor(self, cursor):
         from django.db.backends import util
         return util.CursorDebugWrapper(cursor, self)
+
+class BaseDatabaseOperations(object):
+    """
+    This class encapsulates all backend-specific differences, such as the way
+    a backend performs ordering or calculates the ID of a recently-inserted
+    row.
+    """
+    def autoinc_sql(self, table):
+        """
+        Returns any SQL needed to support auto-incrementing primary keys, or
+        None if no SQL is necessary.
+
+        This SQL is executed when a table is created.
+        """
+        return None

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, util
+from django.db.backends import BaseDatabaseWrapper, BaseDatabaseOperations, util
 try:
     import adodbapi as Database
 except ImportError, e:
@@ -48,7 +48,12 @@ def variantToPython(variant, adType):
     return res
 Database.convertVariantToPython = variantToPython
 
+class DatabaseOperations(BaseDatabaseOperations):
+    pass
+
 class DatabaseWrapper(BaseDatabaseWrapper):
+    ops = DatabaseOperations()
+
     def _cursor(self, settings):
         if self.connection is None:
             if settings.DATABASE_NAME == '' or settings.DATABASE_USER == '':
@@ -130,9 +135,6 @@ def get_start_transaction_sql():
 def get_tablespace_sql(tablespace, inline=False):
     return "ON %s" % quote_name(tablespace)
 
-def get_autoinc_sql(table):
-    return None
-
 def get_sql_flush(style, tables, sequences):
     """Return a list of SQL statements required to remove all data from
     all tables in the database (without actually removing the tables

django/db/backends/dummy/base.py

@@ -21,7 +21,12 @@ class DatabaseError(Exception):
 class IntegrityError(DatabaseError):
     pass
 
-class DatabaseWrapper:
+class DatabaseOperations(object):
+    def __getattr__(self, *args, **kwargs):
+        complain()
+
+class DatabaseWrapper(object):
+    ops = DatabaseOperations()
     cursor = complain
     _commit = complain
     _rollback = ignore
@@ -50,7 +55,6 @@ get_drop_foreignkey_sql = complain
 get_pk_default_value = complain
 get_max_name_length = ignore
 get_start_transaction_sql = complain
-get_autoinc_sql = complain
 get_sql_flush = complain
 get_sql_sequence_reset = complain
 

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, util
+from django.db.backends import BaseDatabaseWrapper, BaseDatabaseOperations, util
 try:
     import MySQLdb as Database
 except ImportError, e:
@@ -53,7 +53,12 @@ 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 DatabaseOperations(BaseDatabaseOperations):
+    pass
+
 class DatabaseWrapper(BaseDatabaseWrapper):
+    ops = DatabaseOperations()
+
     def __init__(self, **kwargs):
         super(DatabaseWrapper, self).__init__(**kwargs)
         self.server_version = None
@@ -181,9 +186,6 @@ def get_max_name_length():
 def get_start_transaction_sql():
     return "BEGIN;"
 
-def get_autoinc_sql(table):
-    return None
-
 def get_sql_flush(style, tables, sequences):
     """Return a list of SQL statements required to remove all data from
     all tables in the database (without actually removing the tables

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, util
+from django.db.backends import BaseDatabaseWrapper, BaseDatabaseOperations, util
 from django.utils.encoding import force_unicode
 try:
     import MySQLdb as Database
@@ -63,7 +63,12 @@ class MysqlDebugWrapper:
         else:
             return getattr(self.cursor, attr)
 
+class DatabaseOperations(BaseDatabaseOperations):
+    pass
+
 class DatabaseWrapper(BaseDatabaseWrapper):
+    ops = DatabaseOperations()
+
     def __init__(self, **kwargs):
         super(DatabaseWrapper, self).__init__(**kwargs)
         self.server_version = None
@@ -200,9 +205,6 @@ def get_max_name_length():
 def get_start_transaction_sql():
     return "BEGIN;"
 
-def get_autoinc_sql(table):
-    return None
-
 def get_sql_flush(style, tables, sequences):
     """Return a list of SQL statements required to remove all data from
     all tables in the database (without actually removing the tables

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, util
+from django.db.backends import BaseDatabaseWrapper, BaseDatabaseOperations, util
 from django.utils.datastructures import SortedDict
 from django.utils.encoding import smart_str, force_unicode
 import datetime
@@ -21,7 +21,26 @@ except ImportError, e:
 DatabaseError = Database.Error
 IntegrityError = Database.IntegrityError
 
+class DatabaseOperations(BaseDatabaseOperations):
+    def autoinc_sql(self, table):
+        # To simulate auto-incrementing primary keys in Oracle, we have to
+        # create a sequence and a trigger.
+        sq_name = get_sequence_name(table)
+        tr_name = get_trigger_name(table)
+        sequence_sql = 'CREATE SEQUENCE %s;' % sq_name
+        trigger_sql = """
+            CREATE OR REPLACE TRIGGER %s
+            BEFORE INSERT ON %s
+            FOR EACH ROW
+            WHEN (new.id IS NULL)
+                BEGIN
+                    SELECT %s.nextval INTO :new.id FROM dual;
+                END;/""" % (tr_name, quote_name(table), sq_name)
+        return sequence_sql, trigger_sql
+
 class DatabaseWrapper(BaseDatabaseWrapper):
+    ops = DatabaseOperations()
+
     def _valid_connection(self):
         return self.connection is not None
 
@@ -187,22 +206,6 @@ def get_start_transaction_sql():
 def get_tablespace_sql(tablespace, inline=False):
     return "%sTABLESPACE %s" % ((inline and "USING INDEX " or ""), quote_name(tablespace))
 
-def get_autoinc_sql(table):
-    # To simulate auto-incrementing primary keys in Oracle, we have to
-    # create a sequence and a trigger.
-    sq_name = get_sequence_name(table)
-    tr_name = get_trigger_name(table)
-    sequence_sql = 'CREATE SEQUENCE %s;' % sq_name
-    trigger_sql = """CREATE OR REPLACE TRIGGER %s
-  BEFORE INSERT ON %s
-  FOR EACH ROW
-  WHEN (new.id IS NULL)
-    BEGIN
-      SELECT %s.nextval INTO :new.id FROM dual;
-    END;
-    /""" % (tr_name, quote_name(table), sq_name)
-    return sequence_sql, trigger_sql
-
 def get_drop_sequence(table):
     return "DROP SEQUENCE %s;" % quote_name(get_sequence_name(table))
 

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, BaseDatabaseOperations, util
 try:
     import psycopg as Database
 except ImportError, e:
@@ -57,7 +57,12 @@ class UnicodeCursorWrapper(object):
 
 postgres_version = None
 
+class DatabaseOperations(BaseDatabaseOperations):
+    pass
+
 class DatabaseWrapper(BaseDatabaseWrapper):
+    ops = DatabaseOperations()
+
     def _cursor(self, settings):
         set_tz = False
         if self.connection is None:
@@ -157,9 +162,6 @@ def get_max_name_length():
 def get_start_transaction_sql():
     return "BEGIN;"
 
-def get_autoinc_sql(table):
-    return None
-
 def get_sql_flush(style, tables, sequences):
     """Return a list of SQL statements required to remove all data from
     all tables in the database (without actually removing the tables

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, util
+from django.db.backends import BaseDatabaseWrapper, BaseDatabaseOperations, util
 try:
     import psycopg2 as Database
     import psycopg2.extensions
@@ -19,7 +19,12 @@ psycopg2.extensions.register_type(psycopg2.extensions.UNICODE)
 
 postgres_version = None
 
+class DatabaseOperations(BaseDatabaseOperations):
+    pass
+
 class DatabaseWrapper(BaseDatabaseWrapper):
+    ops = DatabaseOperations()
+
     def _cursor(self, settings):
         set_tz = False
         if self.connection is None:
@@ -111,9 +116,6 @@ def get_max_name_length():
 def get_start_transaction_sql():
     return "BEGIN;"
 
-def get_autoinc_sql(table):
-    return None
-
 def get_sql_flush(style, tables, sequences):
     """Return a list of SQL statements required to remove all data from
     all tables in the database (without actually removing the tables

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, util
+from django.db.backends import BaseDatabaseWrapper, BaseDatabaseOperations, util
 try:
     try:
         from sqlite3 import dbapi2 as Database
@@ -34,7 +34,12 @@ Database.register_converter("TIMESTAMP", util.typecast_timestamp)
 Database.register_converter("decimal", util.typecast_decimal)
 Database.register_adapter(decimal.Decimal, util.rev_typecast_decimal)
 
+class DatabaseOperations(BaseDatabaseOperations):
+    pass
+
 class DatabaseWrapper(BaseDatabaseWrapper):
+    ops = DatabaseOperations()
+
     def _cursor(self, settings):
         if self.connection is None:
             kwargs = {
@@ -143,9 +148,6 @@ def get_max_name_length():
 def get_start_transaction_sql():
     return "BEGIN;"
 
-def get_autoinc_sql(table):
-    return None
-
 def get_sql_flush(style, tables, sequences):
     """
     Return a list of SQL statements required to remove all data from