README.md

json-to-elm

Decodes JSON into a custom Elm type and provides helpers for generating encoders and decoders for that with elm-codegen.

When to Use

This package was designed and built to help with taking JSON of an unknown shape and generating code for encoding / decoding it with elm-codegen. I'm not sure if there are many good uses for this package beyond that use-case!

Quick Start

To get started, run the decode function with some JSON. This can be JSON encoded in your Elm app or JSON from an external source, like flags or ports.

decodeToElm : Json.Decode.Value -> Result Json.Decode.Error JsonToElm.Value
decodeToElm json =
    Json.Decode.decodeValue JsonToElm.decode json

If the JSON passed to the function above had this shape:

{
    "name": "Joshua",
    "friends": ["John", "Cindy", "Leslie"],
    "active": "true"
}

It would result in the following JsonToElm.Value being returned:

JsonToElm.Record
    (Dict.fromList 
        [ ( "name", JsonToElm.StringVal "Joshua" )
        , ( "friends"
          , JsonToElm.ListVal 
            [ JsonToElm.StringVal "John"
            , JsonToElm.StringVal "Cindy"
            , JsonToElm.StringVal "Leslie"
            ] 
          )
        , ( "active", JsonToElm.BoolVal True )
        ]
    )