Hello TG Group, Examining TG2.2 I found that now it has an option to support load balancing using SQLAlchemy Master Slave Load Balancing.
What it does is to subclass sqlalchemy.orm.Session, overrides get_bind method, and sets it in the sessionmaker as class_; much like A. Molina explain in other post but now I kind of get it. I'm interested in beeing able to select a database depending from where my app gets the request. So I figure to copy the balanced session method and adapt it to my needs. I have two scenarios, The request comes from: http://*db_one*.myapp.com I want to select the database db_one ------ The request comes from: http://myapp.com/*db_one* ------ In the first one dbname = request.host.split('.myapp.com')[0] db_url = config['sqlalchemy.url'].replace('dbname', dbname) engine = create_engine(db_url, pool_recycle=3600) The second one I haven't realized yet, maybe I'll try with a parameter like ac=db_one on the url. When I try to implement this for the first scenario I get 'TypeError: No object (name: request) has been registered for this thread' When the method is called 'request' object is 'request: <paste.registry.StackedObjectProxy object at 0x90a4e0c>' meaning is not yet defined. Looking at the TG stack WSGI Server PasteCascade - serves one of a list of WSGI apps. StaticFile Server - serves static files from /public OR TurboGears Application: - the TG stack *Registry Manager* - sets up the request proxy, etc. Error Middleware - if the path goes to _debug handle the request *Database Session Manager* - setup the DBSession Transaction Manager - Authentication - add info to the environ if user is authenticated Authorization - add more info to the environ for authorization. ToscaWidgets - nothing on the way in. Cache - sets up the cache Session - sets up the web session Routes - parses the URL and adds info to environ Custom Middleware - User defined middleware TurboGearsApp – calls WSGI style controller ObjectDispatchController – gets params, do validation, etc Your Controller Code – does anything! ObjectDispatchController – renders response, etc. ToscaWidgets - injects resources used by widgets Transaction Manager - commits or rolls back transaction Database Session Manager - cleans up the DBSession Error Middleware - displays error pages, etc The request proxy is set before the db session manager so I don't know why is request getting called before assignment. Any orientation will be appreciated. Thanks -- You received this message because you are subscribed to the Google Groups "TurboGears" group. To view this discussion on the web visit https://groups.google.com/d/msg/turbogears/-/jeP6Efo1afkJ. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/turbogears?hl=en.
