gistfile1.py

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, create_engine
from sqlalchemy.orm import sessionmaker

Base = declarative_base()
class Info(Base):
    __tablename__ = 'infos'
    
    id = Column(Integer, primary_key=True)
    keyword = Column(String, unique=True)
    response = Column(String)

    def __init__(self, key, response):
        self.keyword = key
        self.response = response

    def __repr__(self):
        return "<Info('%s', '%s', '%s')>" % (self.keyword, self.response)

class InfoExists(Exception): pass
class NoSuchData(Exception): pass

class InfoManager(object):
    def __init__(self, db="/:memory:"):
        self.engine = create_engine('sqlite://%s' % db, echo=True)
        Base.metadata.create_all(self.engine)
        Session = sessionmaker(bind=self.engine)
        self.session = Session()
        
    def addInfo(self, key, response, replace=False):
        key = key.lower()
        exists = self.session.query(Info).filter_by(keyword=key)
        
        if exists.count():
            if not replace:
                raise InfoExists, key
        
        if exists.count():
            info = exists
            info.response = response
        else:
            info = Info(key, response)
            self.session.add(info)
            
        self.session.commit()
        return info
        
    def getInfo(self, key):
        key = key.lower()
        exists = self.session.query(Info).filter_by(keyword=key)
        
        if not exists.count():
            return NoSuchData, key
            
        return exists.first().response

if __name__ == "__main__":
    m = InfoManager()

    print "Adding bot"
    m.addInfo("bot", "I am a bot")

    print "Adding EntityReborn"
    m.addInfo("EntityReborn", "He's my owner")

    try:
        print "Trying to redefine bot, without replacing"
        m.addInfo("bot", "should make an error")
    except InfoExists, key:
        print "Passed, InfoExists raised for %s" % key
        
    try:
        print "Trying to replace bot"
        info = m.addInfo("bot", "Updated!", True)
        print "Passed, bot is now '%s'" % info.response
    except InfoExists, key:
        print "Got infoexists, %s" % key
    except Exception, err:
        print "Got error: %s" % err

    print "EntityReborn is '%s'" % m.getInfo("EntityReborn") # All good.
    print "bot is '%s'" % m.getInfo("bot") # Should be "Updated!", returns "I am a bot"