"""Support for the MySQL database via the MySQL-python adapter.
MySQL-Python is available at:
http://sourceforge.net/projects/mysql-python
At least version 1.2.1 or 1.2.2 should be used.
Connecting
-----------
Connect string format::
mysql+mysqldb://<user>:<password>@<host>[:<port>]/<dbname>
Character Sets
--------------
Many MySQL server installations default to a ``latin1`` encoding for client
connections. All data sent through the connection will be converted into
``latin1``, even if you have ``utf8`` or another character set on your tables
and columns. With versions 4.1 and higher, you can change the connection
character set either through server configuration or by including the
``charset`` parameter in the URL used for ``create_engine``. The ``charset``
option is passed through to MySQL-Python and has the side-effect of also
enabling ``use_unicode`` in the driver by default. For regular encoded
strings, also pass ``use_unicode=0`` in the connection arguments::
# set client encoding to utf8; all strings come back as unicode
create_engine('mysql+mysqldb:///mydb?charset=utf8')
# set client encoding to utf8; all strings come back as utf8 str
create_engine('mysql+mysqldb:///mydb?charset=utf8&use_unicode=0')
Known Issues
-------------
MySQL-python at least as of version 1.2.2 has a serious memory leak related
to unicode conversion, a feature which is disabled via ``use_unicode=0``.
The recommended connection form with SQLAlchemy is::
engine = create_engine('mysql://scott:tiger@localhost/test?charset=utf8&use_unicode=0', pool_recycle=3600)
"""
import re
from sqlalchemy.dialects.mysql.base import (MySQLDialect,MySQLExecutionContext
MySQLCompiler, MySQLIdentifierPreparer)
from sqlalchemy.engine import base
from sqlalchemy.sql import operators
from sqlalchemy import exc,log,schema,sql,types
from sqlalchemy import processors
class MySQLExecutionContext_mysqldb(MySQLExecutionContext):
@property
def rowcount(self):
if hasattr(self, '_rowcount'):
return self._rowcount
else:
return self.cursor.rowcount
class MySQLCompiler_mysqldb(MySQLCompiler):
def visit_mod(self, binary, **kw):
return self.process(binary.left) + " %% " + self.process(binary.right)
def post_process_text(self, text):
return text.replace('%', '%%')
class MySQLIdentifierPreparer_mysqldb(MySQLIdentifierPreparer):
def _escape_identifier(self, value):
value = value.replace(self.escape_quote, self.escape_to_quote)
return value.replace("%", "%%")
class MySQLDialect_mysqldb(MySQLDialect):
driver = 'mysqldb'
supports_unicode_statements = False
supports_sane_rowcount = True
supports_sane_multi_rowcount = True
supports_native_decimal = True
default_paramstyle = 'format'
execution_ctx_cls = MySQLExecutionContext_mysqldb
statement_compiler = MySQLCompiler_mysqldb
preparer = MySQLIdentifierPreparer_mysqldb
colspecs = util.update_copy(
MySQLDialect.colspecs,
{
}
)
@classmethod
def dbapi(cls):
return __import__('MySQLdb')
def do_executemany(self, cursor, statement, parameters, context=None):
rowcount = cursor.executemany(statement, parameters)
if context is not None:
context._rowcount = rowcount
def create_connect_args(self, url):
opts = url.translate_connect_args(database='db', username='user',
password='passwd')
opts.update(url.query)
util.coerce_kw_type(opts, 'compress', bool)
util.coerce_kw_type(opts, 'connect_timeout', int)
util.coerce_kw_type(opts, 'client_flag', int)
util.coerce_kw_type(opts, 'local_infile', int)
# Note: using either of the below will cause all strings to be returned
# as Unicode, both in raw SQL operations and with column types like
# String and MSString.
util.coerce_kw_type(opts, 'use_unicode', bool)
util.coerce_kw_type(opts, 'charset', str)
# Rich values 'cursorclass' and 'conv' are not supported via
# query string.
ssl = {}
for key in ['ssl_ca', 'ssl_key', 'ssl_cert', 'ssl_capath', 'ssl_cipher']:
if key in opts:
ssl[key[4:]] = opts[key]
util.coerce_kw_type(ssl, key[4:], str)
del opts[key]
if ssl:
opts['ssl'] = ssl
# FOUND_ROWS must be set in CLIENT_FLAGS to enable
# supports_sane_rowcount.
client_flag = opts.get('client_flag', 0)
if self.dbapi is not None:
try:
from MySQLdb.constants import CLIENT
client_flag |= CLIENT_FLAGS.FOUND_ROWS
except:
pass
opts['client_flag'] = client_flag
return [[], opts]
def _get_server_version_info(self, connection):
dbapi_con = connection.connection
version = []
r = re.compile('[.\-]')
for n in r.split(dbapi_con.get_server_info()):
try:
version.append(int(n))
except ValueError:
version.append(n)
return tuple(version)
def _extract_error_code(self, exception):
try:
return exception.orig.args[0]
except AttributeError:
return None
def _detect_charset(self, connection):
"""Sniff out the character set in use for connection results."""
# Note: MySQL-python 1.2.1c7 seems to ignore changes made
# on a connection via set_character_set()
if self.server_version_info < (4, 1, 0):
try:
return connection.connection.character_set_name()
except AttributeError:
# < 1.2.1 final MySQL-python drivers have no charset support.
# a query is needed.
pass
# Prefer 'character_set_results' for the current connection over the
# value in the driver. SET NAMES or individual variable SETs will
# change the charset without updating the driver's view of the world.
#
# If it's decided that issuing that sort of SQL leaves you SOL, then
# this can prefer the driver value.
rs = connection.execute("SHOW VARIABLES LIKE 'character_set%%'")
opts = dict([(row[0], row[1]) for row in self._compat_fetchall(rs)])
if 'character_set_results' in opts:
return opts['character_set_results']
try:
return connection.connection.character_set_name()
except AttributeError:
# Still no charset on < 1.2.1 final...
if 'character_set' in opts:
return opts['character_set']
else:
util.warn(
"Could not detect the connection character set with this "
"combination of MySQL server and MySQL-python. "
"MySQL-python >= 1.2.2 is recommended. Assuming latin1.")
return 'latin1'
dialect = MySQLDialect_mysqldb
|