Its not trivial. Apparently, the mongodb driver isn't exactly ready for showtime. AFAIK, the context monad is a reader monad that contains the connection parameters for mongo. I never got it to work. Greg might know more. Max On Jun 29, 2011, at 4:17 PM, Kamil Ciemniewski wrote:
Hi all,
I've got some "newbie" problems using MongoDB as backend in Persistent.
Basically I've got my app type defined as: data MyApp = MyApp { getStatic :: Static -- ^ Settings for static file serving. , connPool :: ConnPool Host }
And I made it an instance of YesodPersist by: instance YesodPersist MyApp where type YesodDB MyApp = MongoDBReader Host runDB db = liftIOHandler $ fmap connPool getYesod >>= (\p -> return (p, "localhost")) >>= runMongoDBConn db
And I made it an instance of YesodAuth as well by: instance YesodAuth MyApp where type AuthId MyApp = UserId
loginDest _ = RootR logoutDest _ = RootR
getAuthId creds = runDB $ do x <- getBy $ UniqueUser $ credsIdent creds case x of Just (uid, _) -> return $ Just uid Nothing -> do fmap Just $ insert $ User (credsIdent creds) Nothing
authPlugins = [ authEmail ]
I've defined User model as yesod scaffold tool defines it.
Now, when I try to compile it i get:
No instances for (Control.Monad.Context.Context Database.MongoDB.Connection.MasterOrSlaveOk (GGHandler s MyApp IO), Control.Monad.Context.Context Database.MongoDB.Query.Database (GGHandler s MyApp IO), Control.Monad.Context.Context Database.MongoDB.Internal.Protocol.Pipe (GGHandler s MyApp IO), Control.Monad.Context.Context Database.MongoDB.Query.WriteMode (GGHandler s MyApp IO), Control.Monad.Throw.Throw Database.MongoDB.Query.Failure (GGHandler s MyApp IO)) arising from a use of `insert' Possible fix: add instance declarations for (Control.Monad.Context.Context Database.MongoDB.Connection.MasterOrSlaveOk (GGHandler s MyApp IO), Control.Monad.Context.Context Database.MongoDB.Query.Database (GGHandler s MyApp IO), Control.Monad.Context.Context Database.MongoDB.Internal.Protocol.Pipe (GGHandler s MyApp IO), Control.Monad.Context.Context Database.MongoDB.Query.WriteMode (GGHandler s MyApp IO), Control.Monad.Throw.Throw Database.MongoDB.Query.Failure (GGHandler s MyApp IO)) In the expression: insert In the second argument of `($)', namely `insert $ User (credsIdent creds) Nothing' In the expression: fmap Just $ insert $ User (credsIdent creds) Nothing
The problem is probably very trivial.. But I've got no ideas how to fix it.
Best regards Kamil Ciemniewski _______________________________________________ web-devel mailing list web-devel@haskell.org http://www.haskell.org/mailman/listinfo/web-devel