hi, all:
python's version: 2.6.
MySQLdb version: 1.2.3.
I once encounter with a question like this:
File
"/usr/local/lib/python2.6/dist-packages/MySQL_python-1.2.3-py2.6-linux-x86_64.egg/MySQLdb/connections.py",
line 36, in defaulterrorhandler
raise errorclass, errorvalue
OperationalError: (2006, 'MySQL server has gone away')
and i try to find the exception is how to perform to us in the source code.
when i read the source code, some questions puzzled me!
question 1： how to find the words "2006, 'MySQL server has gone away" in
sourced code?
question 2: in MySQLdb/cursors.py , the method errorhandler() just receive
two parameters such as exc,value when it's be invoked. however, in
MySQLdb/connection.py, we define it as one receives 4 parameters such
connection, cursor, erorclass, errorvalue
a method should accepts 4 parameters is invoked by 2
parameters. how to explain it?
question 3: in MySQLdb/connection.py, the module cursors is been imported.
while, In MySQLdb/cursors.py, some methods such as errorhandler in
MySQLdb/connection.py is been invoked.
the two module, which one is execute first? which one is
added to mem first?
some important codes are shown as follows.
any response will be welcome!
-- Jia Xiaolei
-----------------------------------------------------------------------------------
source code about MySQLdb
------------------------------------------------------
# MySQLdb/connections.py
import cursors
def defaulterrorhandler(connection, cursor, errorclass, errorvalue):
"""
If cursor is not None, (errorclass, errorvalue) is appended to
cursor.messages; otherwise it is appended to
connection.messages. Then errorclass is raised with errorvalue as
the value.
You can override this with your own error handler by assigning it
to the instance.
"""
error = errorclass, errorvalue
if cursor:
cursor.messages.append(error)
else:
connection.messages.append(error)
del cursor
del connection
raise errorclass, errorvalue
class Connection(_mysql.connection):
"""MySQL Database Connection Object"""
default_cursor = cursors.Cursor
errorhandler = defaulterrorhandler
def __init__(self, *args, **kwargs):
# some codes
self.cursorclass = kwargs2.pop('cursorclass', self.default_cursor)
charset = kwargs2.pop('charset', '')
def cursor(self, cursorclass=None):
"""
Create a cursor on which queries may be performed. The
optional cursorclass parameter is used to create the
Cursor. By default, self.cursorclass=cursors.Cursor is
used.
"""
return (cursorclass or self.cursorclass)(self)
def xx(yy):
# some codes
# MySQLdb/cursors.py
class BaseCursor(object):
def __init__(self, connection):
from weakref import proxy
self.connection = proxy(connection)
self.description = None
self.description_flags = None
self.rowcount = -1
self.arraysize = 1
self._executed = None
self.lastrowid = None
self.messages = []
self.errorhandler = connection.errorhandler
self._result = None
self._warnings = 0
self._info = None
self.rownumber = None
def execute(self, query, args=None):
"""Execute a query.
query -- string, query to execute on server
args -- optional sequence or mapping, parameters to use with query.
Note: If args is a sequence, then %s must be used as the
parameter placeholder in the query. If a mapping is used,
%(key)s must be used as the placeholder.
Returns long integer rows affected, if any
"""
from types import ListType, TupleType
from sys import exc_info
del self.messages[:]
db = self._get_db()
charset = db.character_set_name()
if isinstance(query, unicode):
query = query.encode(charset)
if args is not None:
query = query % db.literal(args)
try:
r = self._query(query)
except TypeError, m:
if m.args[0] in ("not enough arguments for format string",
"not all arguments converted"):
self.messages.append((ProgrammingError, m.args[0]))
self.errorhandler(self, ProgrammingError, m.args[0])
else:
self.messages.append((TypeError, m))
self.errorhandler(self, TypeError, m)
except:
exc, value, tb = exc_info()
del tb
self.messages.append((exc, value))
self.errorhandler(self, exc, value)
self._executed = query
if not self._defer_warnings: self._warning_check()
return r
class Cursor(CursorStoreResultMixIn, CursorTupleRowsMixIn,
BaseCursor):
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