Haskell Persistent: how get entity from db by key if i have key in integer variable?

问题

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 of type "Key Entity" without calling keyFromValues.

PS Sorry for my poor English

回答1:

You can use toSqlKey for that.

来源：https://stackoverflow.com/questions/28068447/haskell-persistent-how-get-entity-from-db-by-key-if-i-have-key-in-integer-varia