persistent

I'm working on a program in Python for Windows, and would like to save variables and user preferences so that I can recall them even after the program has been terminated and restarted. Is there an ideal way to do this on Windows machines? Would _winreg and the Windows registry be suited for this task? Or do I need to create some sort of database of my own? You're usually going to want to store it in a configuration folder in the "home" folder. That's easy on *nix systems, more difficult in windows, because you actually need to get the "application data" directory. This usually works for me:

I am trying to use Database.Persistant to make a database for a Scotty app, and I cannot figure out the syntax for adding a foreign key constraint between tables. For example, I have a User table and a Post table, and I want the Post table to have an attribute authorId which references UserId in User . This can be accomplished quite easily in raw SQL, but I want to be able to access the data through haskell without resorting to raw sql commands. Also, the constraints would be overwritting upon database migrations. This is what I have at the moment to define the database: share [mkPersist

For my previous question on chaining failures, Michael Snoyman had suggested I use MaybeT to run them so if any of them fails, it will just short-circuit to Nothing . I was under the impression runDb runs everything in a transaction. So shouldn't a failure at any point in code automatically rollback the transaction? mauth <- runDb $ runMaybeT $ do valid <- MaybeT $ return $ listToMaybe errs uid <- MaybeT $ insertUnique u vid <- MaybeT $ getBy $ UniqueField v -- this step fails but previous insert does not roll back auth <- liftIO $ createAuthToken uid return auth When I run the above code, the

I use Persistent orm with scotty web framework. I want to get value from db by id. These id are coming to me from GET request There are "get" function that takes "Key Entity" variable and returns "Maybe Entity". I use following code to get value from db k <- keyFromValues $ [(PersistInt64 myOwnIntVarFromRequest)] case k of Left _ -> {-some processing-} Right x -> do t <- liftIO . runDb $ get (x::Key Post) --Post is one of my models case t of Nothing -> {-processing-} Just x -> {-processing-} These code is extremly ugly. But i don't know how to do it better So my question is how obtain variable

Haskell and Yesod newbie here. I've been trying to follow the Integration with Yesod example from the Persistent chapter in the Yesod book (http://www.yesodweb.com/book/persistent). The Sqlite compiles and runs fine it seems. However, I'm trying to use MongDB and am having a hard time getting things to work. Specifically: In the example for sqlite: share [mkPersist sqlSettings, mkMigrate "migrateAll"] [persist| The Yesod book says "Mongo code will use mongoSettings instead." But I can't find it in any of the modules, and the code doesn't compile. So instead, I had to use this instead of