Fixed #2635 -- Added improved MySQL backend support from Andy Dustman. Also

added database.txt documentation; currently only describing Django-related
features of MySQL versions.

As of this commit, there are four known test failures due to (a) no transaction
support with MyISAM storage engine and (b) MySQLdb automatically creating
decimal types for Django's "float" field.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@4724 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/backends/mysql/base.py

@@ -10,6 +10,9 @@ try:
 except ImportError, e:
     from django.core.exceptions import ImproperlyConfigured
     raise ImproperlyConfigured, "Error loading MySQLdb module: %s" % e
+if Database.version_info < (1,2,1,'final',2):
+    raise ImportError, "MySQLdb-1.2.1p2 or newer is required; you have %s" % MySQLdb.__version__
+
 from MySQLdb.converters import conversions
 from MySQLdb.constants import FIELD_TYPE
 import types
@@ -17,11 +20,14 @@ import re
 
 DatabaseError = Database.DatabaseError
 
+# MySQLdb-1.2.1 supports the Python boolean type, and only uses datetime
+# module for time-related columns; older versions could have used mx.DateTime
+# or strings if there were no datetime module. However, MySQLdb still returns
+# TIME columns as timedelta -- they are more like timedelta in terms of actual
+# behavior as they are signed and include days -- and Django expects time, so
+# we still need to override that.
 django_conversions = conversions.copy()
 django_conversions.update({
-    types.BooleanType: util.rev_typecast_boolean,
-    FIELD_TYPE.DATETIME: util.typecast_timestamp,
-    FIELD_TYPE.DATE: util.typecast_date,
     FIELD_TYPE.TIME: util.typecast_time,
 })
 
@@ -31,31 +37,12 @@ django_conversions.update({
 # http://dev.mysql.com/doc/refman/5.0/en/news.html .
 server_version_re = re.compile(r'(\d{1,2})\.(\d{1,2})\.(\d{1,2})')
 
-# This is an extra debug layer over MySQL queries, to display warnings.
-# It's only used when DEBUG=True.
-class MysqlDebugWrapper:
-    def __init__(self, cursor):
-        self.cursor = cursor
-
-    def execute(self, sql, params=()):
-        try:
-            return self.cursor.execute(sql, params)
-        except Database.Warning, w:
-            self.cursor.execute("SHOW WARNINGS")
-            raise Database.Warning, "%s: %s" % (w, self.cursor.fetchall())
-
-    def executemany(self, sql, param_list):
-        try:
-            return self.cursor.executemany(sql, param_list)
-        except Database.Warning, w:
-            self.cursor.execute("SHOW WARNINGS")
-            raise Database.Warning, "%s: %s" % (w, self.cursor.fetchall())
-
-    def __getattr__(self, attr):
-        if self.__dict__.has_key(attr):
-            return self.__dict__[attr]
-        else:
-            return getattr(self.cursor, attr)
+# MySQLdb-1.2.1 and newer automatically makes use of SHOW WARNINGS on
+# MySQL-4.1 and newer, so the MysqlDebugWrapper is unnecessary. Since the
+# point is to raise Warnings as exceptions, this can be done with the Python
+# warning module, and this is setup when the connection is created, and the
+# standard util.CursorDebugWrapper can be used. Also, using sql_mode
+# TRADITIONAL will automatically cause most warnings to be treated as errors.
 
 try:
     # Only exists in Python 2.4+
@@ -83,28 +70,31 @@ class DatabaseWrapper(local):
 
     def cursor(self):
         from django.conf import settings
+        from warnings import filterwarnings
         if not self._valid_connection():
             kwargs = {
-                'user': settings.DATABASE_USER,
-                'db': settings.DATABASE_NAME,
-                'passwd': settings.DATABASE_PASSWORD,
                 'conv': django_conversions,
             }
+            if settings.DATABASE_USER:
+                kwargs['user'] = settings.DATABASE_USER
+            if settings.DATABASE_NAME:
+                kwargs['db'] = settings.DATABASE_NAME
+            if settings.DATABASE_PASSWORD:
+                kwargs['passwd'] = settings.DATABASE_PASSWORD
             if settings.DATABASE_HOST.startswith('/'):
                 kwargs['unix_socket'] = settings.DATABASE_HOST
-            else:
+            elif settings.DATABASE_HOST:
                 kwargs['host'] = settings.DATABASE_HOST
             if settings.DATABASE_PORT:
                 kwargs['port'] = int(settings.DATABASE_PORT)
             kwargs.update(self.options)
             self.connection = Database.connect(**kwargs)
             cursor = self.connection.cursor()
-            if self.connection.get_server_info() >= '4.1':
-                cursor.execute("SET NAMES 'utf8'")
         else:
             cursor = self.connection.cursor()
         if settings.DEBUG:
-            return util.CursorDebugWrapper(MysqlDebugWrapper(cursor), self)
+            filterwarnings("error", category=Database.Warning)
+            return util.CursorDebugWrapper(cursor, self)
         return cursor
 
     def _commit(self):