BoumTAC BoumTAC - 3 months ago 15
JSON Question

ELM how to decode different value in json array

I have a JSON array with different value in the array and I don't know how to parse it. Here is an example:

"firstname": "John",
"lastname": "Doe",
"age": 30
"companyName": "Doe enterprise",
"location": "NYC",
"numberOfEmployee": 10

So my JSON is like this, the first element of the array is an user, and the second a company.
I have the equivalent in Elm:

type alias User =
{ firsname : String
, lastname : String
, age : Int

type alias Company =
{ companyName : String
, location : String
, numberOfEmployee : Int

Task.perform FetchFail FetchPass (Http.get decodeData url)

So how do I get my
pass in my
function ?
There is something like
but it's for object only.
Here there a way to do something like this ?

decodeData = [0] userDecoder [1] companyDecoder

Answer works for array indexes as well. First you'll need a Data type to hold the user and company:

import Json.Decode as Json exposing ((:=))

type alias Data =
  { user : User
  , company : Company

And you'll need simple decoders for user and company:

userDecoder : Json.Decoder User
userDecoder =
  Json.object3 User
    ("firstname" := Json.string)
    ("lastname" := Json.string)
    ("age" :=

companyDecoder : Json.Decoder Company
companyDecoder =
  Json.object3 Company
    ("companyName" := Json.string)
    ("location" := Json.string)
    ("numberOfEmployee" :=

And finally you can use to get the values at those array indexes. The difference from your example is that you need to pass a string containing an integer index instead of an int:

dataDecoder : Json.Decoder Data
dataDecoder =
  Json.object2 Data
    ( ["0"] userDecoder)
    ( ["1"] companyDecoder)