ELM:如何解码JSONAPI中的数据?

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我有这些数据http://jsonapi.org/format:

{
    "data": [
        {
            "type": "prospect",
            "id": "1",
            "attributes": {
                "provider_user_id": "1",
                "provider": "facebook",
                "name": "Julia",
                "invitation_id": 25
            }
        },
        {
            "type": "prospect",
            "id": "2",
            "attributes": {
                "provider_user_id": "2",
                "provider": "facebook",
                "name": "Sam",
                "invitation_id": 23
            }
        }
    ]
}

模型:

type alias Model = {
  id: Int,
  invitation: Int,
  name: String,
  provider: String,
  provider_user_id: Int
 }

 type alias Collection = List Model

我想把JSON解码成一个集合,但是不知道怎么做。

fetchAll: Effects Actions.Action
fetchAll =
  Http.get decoder (Http.url prospectsUrl [])
   |> Task.toResult
   |> Task.map Actions.FetchSuccess
   |> Effects.task

decoder: Json.Decode.Decoder Collection
decoder =
  ?

如何实现解码器?谢谢

提问于
用户回答回答于

N.B.Json.Decode文档

试试这个:

import Json.Decode as Decode exposing (Decoder)
import String

-- <SNIP>

stringToInt : Decoder String -> Decoder Int
stringToInt d =
  Decode.customDecoder d String.toInt

decoder : Decoder Model
decoder =
  Decode.map5 Model
    (Decode.field "id" Decode.string |> stringToInt )
    (Decode.at ["attributes", "invitation_id"] Decode.int)
    (Decode.at ["attributes", "name"] Decode.string)
    (Decode.at ["attributes", "provider"] Decode.string)
    (Decode.at ["attributes", "provider_user_id"] Decode.string |> stringToInt)

decoderColl : Decoder Collection
decoderColl =
  Decode.map identity
    (Decode.field "data" (Decode.list decoder))

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