RemoteData.Http

A collection of helper functions for loading JSON data from a server using RemoteData.

API Documentation

There is an example for each of the functions in the module documentation.

A simple full usage example can be found right here on this readme.

Introduction

RemoteData is a type representing the state of some remote server data. It looks like this:

type RemoteData e a
    = NotAsked
    | Loading
    | Failure e
    | Success a

In this package, we deal with the more specialized version of the type, called WebData:

type alias WebData a =
    RemoteData Http.Error a

This means the Failure case will always have an error from the elm-lang/http package.

For more information, please refer to the package documentation for RemoteData.

Example usage

Using RemoteData.Http looks like this. Play with the code on Ellie.

module Main exposing (..)

import Html exposing (Html, button, text)
import Html.Events exposing (onClick)
import Json.Decode
import RemoteData exposing (RemoteData(..), WebData)
import RemoteData.Http


{-| Store the data as a `WebData a` type in your model
-}
type alias Model =
    { cat : WebData Cat
    }


{-| Add a message with a `WebData a` parameter
-}
type Msg
    = HandleCatResponse (WebData Cat)
    | GetCat


init : ( Model, Cmd Msg )
init =
    ( { cat = NotAsked }
    , Cmd.none
    )


update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
    case msg of
        HandleCatResponse data ->
            ( { model | cat = data }
            , Cmd.none
            )

        GetCat ->
            ( { model | cat = Loading }
            , RemoteData.Http.get "/api/cats/1" HandleCatResponse catDecoder
            )


view : Model -> Html Msg
view model =
    case model.cat of
        Loading ->
            text "Loading cat data, please stand by..."

        Success cat ->
            text ("Received cat: " ++ toString cat)

        Failure error ->
            text ("Oh noes, cat loading failed with error: " ++ toString error)

        NotAsked ->
            button [ onClick GetCat ] [ text "Get cat data from the server" ]


main =
    Html.program
        { init = init
        , update = update
        , view = view
        , subscriptions = \_ -> Sub.none
        }


{- This stuff is just to make it compile...
Replace with your real type and decoder.
-}
type alias Cat =
    {}


catDecoder =
    Json.Decode.fail "this isn't a real decoder"

There is a function to make a command or a task for each of the HTTP verbs, and also the same with some additional configuration.

Take a look at the module documentation.

License

This is made by Ossi Hanhinen and licensed under BSD (3-clause).