file.hs

import Data.Aeson
import Web.HttpApiData (ToHttpApiData(..))

instance FromJSON SFId where
    parseJSON = withText "Id" $ \i -> do
        return $ SFId i

instance ToJSON SFId where
    toJSON (SFId i) = object 
        [ "Id" .= i ]

instance ToHttpApiData SFId where
    toQueryParam (SFId id) = id

-- Now the user can set their adts id field with wtv name they want.

data Account = Account
    { accountId :: SFId
    , name :: Text
    } deriving (Generic, Show)
    
 instance FromJSON Account
 instance ToJSON Account
 
    
 --- This will also automatically handle the SFId for the user. However, I had to create my own FromJSON class because
 --- Salesforce returns other fields that end user will not need.
 --- Example of a reponse when making a get: {attributes: {type: "foo", url:"random"}, Id: "sad2313sda", Name: "new Account"}
 --- My own FromJSON class removes the unedded fields and formats fields name to meet salesforce naming convention. Salesforce naming convention for fields starts with capital letters and 
 --- mixes it with camelCamel cases. I.E: AccountName, AccountNumber 
 

class (Generic a, GFromJSON Zero (Rep a)) => HFFromJSON a where
    myFromJSON :: Value -> Parser a
    myFromJSON (Object v) = genericParseJSON defaultOptions { fieldLabelModifier = firstCharToUpper} v'
        where v' = Object (HMS.delete "attributes" $ v) :: Value

class (Typeable a, Generic a, GToJSON Zero (Rep a)) => HFToJSON a where
    myToJSON :: a -> Value
    myToJSON = genericToJSON defaultOptions { fieldLabelModifier = capitalized }
    
capitalized :: String -> String
capitalized [] = []
capitalized (head:tail) = Char.toUpper head : lowered tail
  where
    lowered [] = []
    lowered (head:tail) = Char.toLower head : lowered tail

firstCharToUpper :: String -> String 
firstCharToUpper (head:tail) = Char.toUpper head : tail