On Wed, Jun 29, 2011 at 11:17 AM, Kamil Ciemniewski
<
ciemniewski.kamil@gmail.com> 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
>