JSON access by Lens

json_access_by_lens.hs

{-# LANGUAGE OverloadedStrings #-}

module Test06 where

import Prelude hiding (readFile, lookup)

import Control.Monad.IO.Class
import Control.Lens
import Data.Aeson
import Data.Aeson.Lens
import qualified Data.ByteString as B

main :: IO () 
main = do
   val <- B.readFile  "test/Data/test01.json"
   print val
   print $ val ^? key "lng"       . nonNull
   print $ val ^? key "lng"       . _String
   print $ val ^? key "resources" . _Object
   print $ val ^? key "resources" . key "en" . key "translation" . _Object
   print $ val ^? key "resources" . key "en" . key "translation" . key "look" . key "deep" . _Value
   print $ val ^? (foldl (.) _Value $ map key ["resources" , "en", "translation"])

{-
test/Data/test01.json

{
  "lng": "en",
  "debug": true,
  "resources": {
   "en": {
        "translation" : {
           "key": "value of key",
           "look": {
              "deep": "value of look deep"
           }
        }   
    }
  }
}

-}