ActionCable in Elm

This package is an Elm client library for ActionCable, which comes bundled with Ruby on Rails.

Basic Usage

import ActionCable
import ActionCable.Msg as ACMsg
import ActionCable.Identifier as ID


initModel : (Model, Cmd Msg)
initModel =
    { cable =
        ActionCable.initCable "ws://localhost:3000/cable/"
            |> ActionCable.onDidReceiveData (Just HandleData)
            |> ActionCable.withDebug True
    , errorToast = Nothing
    , ...
    } ! []


type Msg
    = CableMsg ACMsg.Msg
    | SubscribeTo String
    | UnsubscribeFrom String
    | HandleData ID.Identifier Json.Decode.Value
    | SendData String String


update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
    case msg of
        SubscribeTo roomName ->
          subscribeTo roomName model

        UnsubscribeFrom roomName ->
          unsubscribeFrom roomName model

        HandleData identifier value ->
            -- value is a Json.Decode.Value. You'll probably want to use
            -- Json.Decode.decodeValue
            { model | messages = toString value :: model.messages } ! []

        SendData roomName aStringToSend ->
          sendData roomName aStringToSend model

        CableMsg cableMsg ->
            -- important to forward on "accounting" messages to the underlying submodel
            ActionCable.update cableMsg model.cable
                |> (\( cable, cmd ) -> { model | cable = cable } ! [ cmd ])


subscribeTo : String -> Model -> (Model, Cmd Msg)
subscribeTo roomName model =
    case ActionCable.subscribeTo (channelId roomName) model.cable of
        Ok ( cable, cmd ) ->
            { model | cable = cable } ! [ Cmd.map CableMsg cmd ]

        Err err ->
            -- you're probably already subscribed to this channel
            { model | errorToast = Just <| ActionCable.errorToString err } ! []


unsubscribeFrom : String -> Model -> (Model, Cmd Msg)
unsubscribeFrom roomName model =
    case ActionCable.unsubscribeFrom (channelId roomName) model.cable of
        Ok ( cable, cmd ) ->
            { model | cable = cable } ! [ Cmd.map CableMsg cmd ]

        Err err ->
            -- you're probably already unsubscribed from this channel
            { model | errorToast = Just <| ActionCable.errorToString err } ! []


sendData : String -> String -> Model -> (Model, Cmd Msg)
sendData roomName aStringToSend model =
    let
        sendCmd =
            ActionCable.perform
                "some_channel_action_name"
                [ ( "jsonKey", Json.Encode.string aStringToSend ) ]
                (channelId roomName)
                model.cable
    in
        case sendCmd of
            Ok toSend ->
                model ! [ toSend ]

            Err err ->
                -- probably because you haven't subscribed to the channel yet
                { model | errorToast = Just <| ActionCable.errorToString err } ! []


channelId : String -> ID.Identifier
channelId roomName =
    ID.newIdentifier "ChatChannel" [ ( "room", roomName ) ]


-- subscriptions


subscriptions : Model -> Sub Msg
subscriptions model =
    ActionCable.listen CableMsg model.cable

License

elm-action-cable is released under the Apache v2 license, the details of which can be found in the LICENSE file.

Author

• Brad Grzesiak, Bendyworks