root / pykota / trunk / pykota / storages / pgstorage.py @ 3527

# -*- coding: utf-8 -*-
#
# PyKota : Print Quotas for CUPS
#
# (c) 2003-2009 Jerome Alet <alet@librelogiciel.com>
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# $Id$
#
#

"""This module defines a class to access to a PostgreSQL database backend."""

from types import StringType

from pykota.errors import PyKotaStorageError
from pykota.storage import BaseStorage
from pykota.storages.sql import SQLStorage

from pykota.utils import *

try :
    import pg
except ImportError :
    import sys
    # TODO : to translate or not to translate ?
    raise PyKotaStorageError, "This python version (%s) doesn't seem to have the PygreSQL module installed correctly." % sys.version.split()[0]
else :
    try :
        PGError = pg.Error
    except AttributeError :
        PGError = pg.error

class Storage(BaseStorage, SQLStorage) :
    def __init__(self, pykotatool, host, dbname, user, passwd) :
        """Opens the PostgreSQL database connection."""
        BaseStorage.__init__(self, pykotatool)
        try :
            (host, port) = host.split(":")
            port = int(port)
        except ValueError :
            port = 5432         # Use PostgreSQL's default tcp/ip port (5432).

        self.tool.logdebug("Trying to open database (host=%s, port=%s, dbname=%s, user=%s)..." % (repr(host),
                                                                                                  repr(port),
                                                                                                  repr(dbname),
                                                                                                  repr(user)))
        try :
            self.database = pg.DB(host=host,
                                  port=port,
                                  dbname=dbname,
                                  user=user,
                                  passwd=passwd)
        except PGError, msg :
            msg = "%(msg)s --- the most probable cause of your problem is that PostgreSQL is down, or doesn't accept incoming connections because you didn't configure it as explained in PyKota's documentation." % locals()
            raise PGError, msg
        self.closed = False
        try :
            self.quote = self.database._quote
        except AttributeError : # pg <v4.x
            self.quote = pg._quote
        try :
            self.database.query("SET CLIENT_ENCODING TO 'UTF-8';")
        except PGError, msg :
            self.tool.logdebug("Impossible to set database client encoding to UTF-8 : %s" % msg)
        self.tool.logdebug("Database opened (host=%s, port=%s, dbname=%s, user=%s)" % (repr(host),
                                                                                       repr(port),
                                                                                       repr(dbname),
                                                                                       repr(user)))

    def close(self) :
        """Closes the database connection."""
        if not self.closed :
            self.database.close()
            self.closed = True
            self.tool.logdebug("Database closed.")

    def beginTransaction(self) :
        """Starts a transaction."""
        self.database.query("BEGIN;")
        self.tool.logdebug("Transaction begins...")

    def commitTransaction(self) :
        """Commits a transaction."""
        self.database.query("COMMIT;")
        self.tool.logdebug("Transaction committed.")

    def rollbackTransaction(self) :
        """Rollbacks a transaction."""
        self.database.query("ROLLBACK;")
        self.tool.logdebug("Transaction aborted.")

    def doRawSearch(self, query) :
        """Does a raw search query."""
        query = query.strip()
        if not query.endswith(';') :
            query += ';'
        self.querydebug("QUERY : %s" % query)
        try :
            return self.database.query(query)
        except PGError, msg :
            raise PyKotaStorageError, repr(msg)

    def doSearch(self, query) :
        """Does a search query."""
        result = self.doRawSearch(query)
        if (result is not None) and (result.ntuples() > 0) :
            return result.dictresult()

    def doModify(self, query) :
        """Does a (possibly multiple) modify query."""
        query = query.strip()
        if not query.endswith(';') :
            query += ';'
        self.querydebug("QUERY : %s" % query)
        try :
            return self.database.query(query)
        except PGError, msg :
            self.tool.logdebug("Query failed : %s" % repr(msg))
            raise PyKotaStorageError, repr(msg)

    def doQuote(self, field) :
        """Quotes a field for use as a string in SQL queries."""
        if type(field) == type(0.0) :
            typ = "decimal"
        elif type(field) == type(0) :
            typ = "int"
        elif type(field) == type(0L) :
            typ = "int"
        else :
            typ = "text"
        return self.quote(field, typ)

    def prepareRawResult(self, result) :
        """Prepares a raw result by including the headers."""
        if result.ntuples() > 0 :
            entries = [result.listfields()]
            entries.extend(result.getresult())
            nbfields = len(entries[0])
            for i in range(1, len(entries)) :
                fields = list(entries[i])
                for j in range(nbfields) :
                    field = fields[j]
                    if type(field) == StringType :
                        fields[j] = databaseToUnicode(field)
                entries[i] = tuple(fields)
            return entries