Question

我的应用程序使用Navigate进行路由，但由于某种原因，初始http命令没有为其中一个子模块触发。在父模块和子模块之间连接命令的方式可能有问题，但我可以使用一些帮助来定位问题。代码和结构以elm-taco（https://github.com/ohanhi/elm-taco）为例进行建模。下面是代码相关部分的摘录，没有编译器错误。

Main.elm

init : Flags -> Location -> ( AppModel, Cmd Msg )
init flags location =
        (  startModel
        , Http2.get ("localhost:4000/graphql?query=" ++ encoded) HandleLogDataResponse decoder)

update :  Msg -> AppModel -> ( AppModel, Cmd Msg )
update  msg model =
        case msg of
             HandleLogDataResponse webData ->
                 updateLogData model webData
             RouterMsg routerMsg ->
                 updateRouter model routerMsg

updateLogData :  AppModel -> WebData LogData -> ( AppModel, Cmd Msg )
updateLogData  model webData =
    case webData of
        Success logdata ->
            case model.appState of
                NotReady time ->
                    let
                        initTaco =
                            { currentTime = time
                            , logdata = logdata
                            }
                        ( initRouterModel, routerCmd ) =
                            Router.init initTaco model.location
                    in
                        ( { model | appState = Ready initTaco initRouterModel }
                        , Cmd.map RouterMsg routerCmd
                        )

                Ready taco routerModel ->
                    ( { model | appState = Ready (updateTaco taco (UpdateLogData logdata)) routerModel }
                    , Cmd.none
                    )

Router.elm

init : Taco -> Location -> (Model, Cmd Msg)
init taco location =
    let 
        ( chatModel, chatCmd) =
               Chat.initModel taco
    in
      ( { chatModel = chatModel
      , route = parseLocation location}
      , Cmd.map ChatMsg chatCmd
      )

update: Msg -> Model -> ( Model,Cmd Msg, TacoUpdate)
update msg model =
    case msg of
        ChatMsg chatMsg ->
            updateChat model chatMsg

updateChat : Model -> Chat.Msg -> (Model, Cmd Msg, TacoUpdate)
updateChat model chatMsg =
    let
        ( nextChatModel, chatCmd, tacoUpdate) =
            Chat.update chatMsg model.chatModel
    in
        ( {model | chatModel = nextChatModel }
        , Cmd.map ChatMsg chatCmd
        , tacoUpdate)

Chat.elm

initModel : Taco -> ( Model, Cmd Msg )
initModel taco =
    let
        startModel = { newMessage = ""
                    , messages = taco.messages
                    , response = "Waiting for a response..."
                    , logs = [] 
                    }
        cmd = Http.send FetchHNTopStories request

    in
            ( startModel
            , cmd
        )

Answer 1

为了获得执行命令的结果，您需要为它提供一种到达运行时的方法。

这是通过main完成的。如果您的Cmd未访问该应用的main，则永远不会执行这些内容。

在您提供的代码示例中，子模块init如何到达main并不明显。传统上，init中的Main.elm应使用子模块中的init，Cmd.map子模块init Cmds和Cmd.batch以及其余部分主要init Cmds。

Elm子模块的init命令没有触发

1 个答案: