json-mask

A simple library for filtering JSON using the fields syntax inspired by Google's Partial Response. Field masks remove unnecessary values while retaining the structure of the JSON resource.

Mask Syntax

• a,b,c comma-separated list will select multiple fields
• a/b/c path will select a field from its parent
• a(b,c) sub-selection will select many fields from a parent
• a/*/c the star * wildcard will select all items in a field

Terminal characters ,*()/ can be escaped using a single backslash \.

Usage

import qualified Data.Aeson as Aeson
import qualified Data.Aeson.QQ.Simple as Aeson
import qualified Data.ByteString.Lazy as BSL
import JSONMask (masked)

val :: Aeson.Value
val = [Aeson.aesonQQ|{"p":{"a":1,"b":2},"z":1}|]

main :: IO ()
main = BSL.putStr . Aeson.encode $ masked val "p/a,z"

--  {p: {a: 1}, z: 1}

More examples can be found in the tests.