cursors.py

python联接mysql驱动 python联接mysql驱动

"""MySQLdb Cursors

This module implements Cursors of various types for MySQLdb. By
default, MySQLdb uses the Cursor class.

"""

import re
insert_values = re.compile(r"\svalues\s*(\(((?<!\\)'.*?\).*(?<!\\)?'|.)+?\))", re.IGNORECASE)
from _mysql_exceptions import Warning, Error, InterfaceError, DataError, \
     DatabaseError, OperationalError, IntegrityError, InternalError, \
     NotSupportedError, ProgrammingError


class BaseCursor(object):
    
    """A base for Cursor classes. Useful attributes:
    
    description
        A tuple of DB API 7-tuples describing the columns in
        the last executed query; see PEP-249 for details.

    description_flags
        Tuple of column flags for last query, one entry per column
        in the result set. Values correspond to those in
        MySQLdb.constants.FLAG. See MySQL documentation (C API)
        for more information. Non-standard extension.
    
    arraysize
        default number of rows fetchmany() will fetch

    """

    from _mysql_exceptions import MySQLError, Warning, Error, InterfaceError, \
         DatabaseError, DataError, OperationalError, IntegrityError, \
         InternalError, ProgrammingError, NotSupportedError
    
    _defer_warnings = False
    
    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 __del__(self):
        self.close()
        self.errorhandler = None
        self._result = None
        
    def close(self):
        """Close the cursor. No further queries will be possible."""
        if not self.connection: return
        while self.nextset(): pass
        self.connection = None

    def _check_executed(self):
        if not self._executed:
            self.errorhandler(self, ProgrammingError, "execute() first")

    def _warning_check(self):
        from warnings import warn
        if self._warnings:
            warnings = self._get_db().show_warnings()
            if warnings:
                # This is done in two loops in case
                # Warnings are set to raise exceptions.
                for w in warnings:
                    self.messages.append((self.Warning, w))
                for w in warnings:
                    warn(w[-1], self.Warning, 3)
            elif self._info:
                self.messages.append((self.Warning, self._info))
                warn(self._info, self.Warning, 3)

    def nextset(self):
        """Advance to the next result set.

        Returns None if there are no more result sets.
        """
        if self._executed:
            self.fetchall()
        del self.messages[:]
        
        db = self._get_db()
        nr = db.next_result()
        if nr == -1:
            return None
        self._do_get_result()
        self._post_get_result()
        self._warning_check()
        return 1

    def _post_get_result(self): pass
    
    def _do_get_result(self):
        db = self._get_db()
        self._result = self._get_result()
        self.rowcount = db.affected_rows()
        self.rownumber = 0
        self.description = self._result and self._result.describe() or None
        self.description_flags = self._result and self._result.field_flags() or None
        self.lastrowid = db.insert_id()
        self._warnings = db.warning_count()
        self._info = db.info()
    
    def setinputsizes(self, *args):
        """Does nothing, required by DB API."""
      
    def setoutputsizes(self, *args):
        """Does nothing, required by DB API."""

    def _get_db(self):
        if not self.connection:
            self.errorhandler(self, ProgrammingError, "cursor closed")
        return self.connection
    
    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

    def executemany(self, query, args):

        """Execute a multi-row query.
        
        query -- string, query to execute on server

        args

            Sequence of sequences or mappings, parameters to use with
            query.
            
        Returns long integer rows affected, if any.
        
        This method improves performance on multiple-row INSERT and
        REPLACE. Otherwise it is equivalent to looping over args with
        execute().

        """
        del self.messages[:]
        db = self._get_db()
        if not args: return
        charset = db.character_set_name()
        if isinstance(query, unicode): query = query.encode(charset)
        m = insert_values.search(query)
        if not m:
            r = 0
            for a in args:
                r = r + self.execute(query, a)
            return r
        p = m.start(1)
        e = m.end(1)
        qv = m.group(1)
        try:
            q = [ qv % db.literal(a) for a in args ]
        except TypeError, msg:
            if msg.args[0] in ("not enough arguments for format string",
                               "not all arguments converted"):
                self.messages.append((ProgrammingError, msg.args[0]))
                self.errorhandler(self, ProgrammingError, msg.args[0])
            else:
                self.messages.append((TypeError, msg))
                self.errorhandler(self, TypeError, msg)
        except:
            from sys import exc_info
            exc, value, tb = exc_info()
            del tb
            self.errorhandler(self, exc, value)
        r = self._query('\n'.join([query[:p], ',\n'.join(q), query[e:]]))
        if not self._defer_warnings: self._warning_check()
        return r
    
    def callproc(self, procname, args=()):

        """Execute stored procedure procname with args
        
        procname -- string, name of procedure to execute on server

        args -- Sequence of parameters to use with procedure

        Returns the original args.

        Compatibility warning: PEP-249 specifies that any modified
        parameters must be returned. This is currently impossible
        as they are only available by storing them in a server
        variable and then retrieved by a query. Since stored
        procedures return zero or more result sets, there is no
        reliable way to get at OUT or INOUT parameters via callproc.
        The server variables are named @_procname_n, where procname
        is the parameter above and n is the position of the parameter
        (from zero). Once all result sets generated by the procedure
        have been fetched, you can issue a SELECT @_procname_0, ...
        query using .execute() to get any OUT or INOUT values.

        Compatibility warning: The act of calling a stored procedure
        itself creates an empty result set. This appears after any
        result sets generated by the procedure. This is non-standard
        behavior with respect to the DB-API. Be sure to use nextset()
        to advance through all result sets; otherwise you may get
        disconnected.
        """