Question

我已成功为elm tutorial实施了删除播放器方法。但是，如果不手动发送ForchFetch msg（通过单击按钮）再次从服务器获取播放器，我无法更新模型。这是我的代码：

我的删除按钮：

deleteBtn : Player -> Html.Html Msg
deleteBtn player =
    let
        message =
            Msgs.Delete player
    in
       a
            [ class "btn regular", onClick message]
            [ i [ class "fa fa-pencil mr1" ] [], text "Delete" ]

我的删除讯息：

type Msg = 
    | Delete Player
    | OnDeletePlayer (Result Http.Error Player) 
    | ForceFetch
    | OnFetchPlayers (WebData (List Player))

我的更新功能：

update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
        Msgs.ForceFetch ->
          (model, fetchPlayers)
        Msgs.OnFetchPlayers response -> 
        ( { model | players = response }, Cmd.none )
        Msgs.Delete player ->
          (model, deletePlayerCmd player)

        Msgs.OnDeletePlayer (Ok player) ->
          (updateDeletedPlayerList model player, Cmd.none)

        Msgs.OnDeletePlayer (Err player) ->
          (model, Cmd.none)

updateDeletedPlayerList : Model -> Player -> Model 
updateDeletedPlayerList model deletedPlayer =     
     let
         updatedPlayers = RemoteData.map (List.filter (\p -> deletedPlayer /= p)) model.players
     in
         { model | players = updatedPlayers}

deletePlayerCmd : Player -> Cmd Msg
deletePlayerCmd player =
      Http.send Msgs.OnDeletePlayer (deletePlayerRequest player)

deletePlayerRequest : Player -> Http.Request Player
deletePlayerRequest player =
 Http.request
        { body = Http.emptyBody
        , expect = Http.expectJson playerDecoder
        , headers = []
        , method = "DELETE"
        , timeout = Nothing
        , url = savePlayerUrl player.id
        , withCredentials = False
        }
fetchPlayers : Cmd Msg
fetchPlayers =
    Http.get fetchPlayersUrl playersDecoder 
        |> RemoteData.sendRequest 
        |> Cmd.map Msgs.OnFetchPlayers

为了衡量我的模型：

type alias Model =
    { players : WebData (List Player)
    , route : Route
    , newPlayerName : String
    , newPlayerId : String
    , newPlayerLevel : Int
    }

编辑：

我尝试以下列方式合并fetchPlayers但没有成功：

Msgs.OnDeletePlayer (Ok player) ->
          (updateDeletedPlayerList model player, fetchPlayers)

Answer 1

如果您不希望在删除后获取模型，则需要更新代码中的模型，因此您可以在以下位置：

Msgs.Delete player ->
          (model, deletePlayerCmd player)

您需要将'model'更改为将从中移除播放器的函数：

    Msgs.Delete player ->
        (removePlayer player model, deletePlayerCmd player)

...
removePlayer : Player -> Model -> Model
...

从elm模型中删除值

1 个答案: