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pythondatabaseasynchronoustornado

Python: Tornado and persistent database connection

I am reading tornado documentation. I would like to have persistent connection(connection is up during application lifetime) to DB and return data from DB asynchronously. Where is the best place of doing this?

  • def initialize ?
  • handler's __init__ method?
  • def prepare?
  • or other place?

Could you provide some examples?

Solution

  • The simplest thing is just to make the database connection object a module-level global variable. See this example from the Motor documentation:

    db = motor.motor_tornado.MotorClient().test_database

application = tornado.web.Application([
    (r'/', MainHandler)
], db=db)

application.listen(8888)
tornado.ioloop.IOLoop.instance().start()

    RequestHandlers could simply use the global variable directly. Also, passing the database as the db keyword argument to Application makes it available to request handlers in their "settings" dict:

    class MainHandler(tornado.web.RequestHandler):
    def get(self):
        db = self.settings['db']

    This might make it easier to access the database object from RequestHandlers defined in other files.