1 from types import StringTypes
3 from sqlalchemy import create_engine
4 from sqlalchemy.orm import sessionmaker
6 from sqlalchemy import Column, Integer, String
7 from sqlalchemy.orm import relationship, backref
8 from sqlalchemy import ForeignKey
10 from sfa.util.sfalogging import logger
12 # this module is designed to be loaded when the configured db server is reachable
13 # OTOH model can be loaded from anywhere including the client-side
17 def __init__ (self, config):
19 # will be created lazily on-demand
21 # the former PostgreSQL.py used the psycopg2 directly and was doing
22 #self.connection.set_client_encoding("UNICODE")
23 # it's unclear how to achieve this in sqlalchemy, nor if it's needed at all
24 # http://www.sqlalchemy.org/docs/dialects/postgresql.html#unicode
25 # we indeed have /var/lib/pgsql/data/postgresql.conf where
26 # this setting is unset, it might be an angle to tweak that if need be
27 # try a unix socket first - omitting the hostname does the trick
28 unix_url = "postgresql+psycopg2://%s:%s@:%s/%s"%\
29 (config.SFA_DB_USER,config.SFA_DB_PASSWORD,config.SFA_DB_PORT,dbname)
30 # the TCP fallback method
31 tcp_url = "postgresql+psycopg2://%s:%s@%s:%s/%s"%\
32 (config.SFA_DB_USER,config.SFA_DB_PASSWORD,config.SFA_DB_HOST,config.SFA_DB_PORT,dbname)
33 for url in [ unix_url, tcp_url ] :
35 self.engine = create_engine (url)
42 raise Exception,"Could not connect to database"
45 # expects boolean True: debug is ON or False: debug is OFF
46 def debug (self, echo):
50 self.engine.execute ("select 1").scalar()
53 if self._session is None:
54 Session=sessionmaker ()
55 self._session=Session(bind=self.engine)
58 def close_session (self):
59 if self._session is None: return
64 from sfa.util.config import Config
66 alchemy=Alchemy (Config())
68 dbsession=alchemy.session()