Re: [Haskell-cafe] Using HaskellDb to connect to PostgresSql

On Wed, Mar 19, 2008 at 8:32 PM, Justin Bailey wrote:

On Wed, Mar 19, 2008 at 10:55 AM, Marc Mertens wrote:

...

Hello,

I'm trying to learn to use HaskellDb. I have managed to finally compile and install it on my linux box (I have ghc 6.8.2). But when I try to create a database description (as described in http://haskelldb.sourceforge.net/getting-started.html) (using DBDirect-dynamic instead of DBDirect) I'm stuck. I have tried different names for the driver but

I don't have much information about using DBDynamic, but I am able to connect to PostgreSQL easily. I have done it on Windows using GHC 6.8.2. I am using hdbc-postgresql, since hsql would not compile on Windows for me. Here are the import statements and the login function I have for a simple program that connects to postgresql and writes out table info:

import Database.HaskellDB.DBSpec.DatabaseToDBSpec import Database.HaskellDB.DBSpec.DBSpecToDBDirect import Database.HaskellDB.Database import Database.HaskellDB.HDBC.PostgreSQL import Database.HaskellDB.PrimQuery import Database.HaskellDB.FieldType import Database.HaskellDB.DBSpec

login :: MonadIO m => String -> Int -> String -> String -> String -> (Database -> m a) -> m a login server port user password dbname = postgresqlConnect [("host", server), ("port", show port), ("user", user), ("password", password), ("dbname", dbname)]

The versions of all packages I'm using are:

HDBC-1.1.4 HDBC-postgresql-1.1.4.0 haskelldb-hdbc-0.10 haskelldb-hdbc-postgresql-0.10

Note you might have to modify the haskelldb cabal files to get them to use later versions of HDBC.

As for recent documentation, unfortunately the darcs repository and the code is the best place to go. The haddock documentation doesn't have everything.

Finally, I'd suggest joining the haskell-db users mailing list for specific questions. You can find info about that and the darcs repository on the homepage at http://haskelldb.sourceforge.net.

Justin

Just to add to what Justin said, try using DBDirect-hdbc-postgresql instead of DBDirect-dynamic. The "dynamic" driver adds an extra layer of problems, and I'm not sure that it (or hs-plugins?) has been updated to work with GHC 6.8.2. Because of a typo in a .cabal file, there was no DBDirect-hdbc-postgresql until a few minutes ago, but if you pull down the current darcs version and reinstall haskelldb-hdbc-postgresql you should get it. The HaskellDB documentation really is in a sorry state. Does anybody feel like adding a wiki page with a basic getting-started HaskellDB tutorial? It would be very appreciated. This page seems to contain mostly meta-information: http://www.haskell.org/haskellwiki/Applications_and_libraries/Database_inter... /Björn