Question

我是Elm的新手并试图找出0.17。我想知道是否有人了解我的数据为什么不在此处的视图中呈现。在Chrome控制台中，我可以看到GET请求已成功完成，但它实际上从未显示在页面上。我从URL返回的数据应该是这样的：

[{＆＃34; title＆＃34;：＆＃34; Aut enim quia accusamus。＆＃34;，＆＃34; content＆＃34;：＆＃34; Ipsa aliquid repellendus laudantium velit。使用corrupti qui ut aut autudududndae。 Ipsum molestiae ullam quasi molestiae qui quas。错误nobis cupiditate dolor moortiae officia quod doloribus。＆＃34;}，{＆＃34; title＆＃34;：＆＃34; Architecto assumenda incidunt reprehenderit aut。＆＃34;，＆＃34; content＆＃34;：＆＃34; Praesentium voluptas aspernatur ullam voluptatum odit voluptas。 Tempora dolorum incidunt qui commodi fugit。 Adipisci maiores cum aliquid itaque voluptatem beatae。 Aut minus omnis nihil voluptatem。 Eius praesentium quis deleniti dolorem debitis。＆＃34;}]

module Questions exposing (..)

import List
import Html exposing (..)
import Html.App
import Html.Attributes exposing (..)
import Html.Events as Events
import Http
import Json.Decode as Json exposing ((:=))
import Task exposing (..)

main : Program Never
main =
  Html.App.program
    { init = init
    , update = update
    , view = view
    , subscriptions = \_ -> Sub.none }

--MODEL

type alias Question =
  { title : String
  , content : String }

type alias Model =
  { questions : List Question
  }

initialModel : Model
initialModel =
  { questions = []
  }

questionsDecoder : Json.Decoder (List Question)
questionsDecoder =
  Json.list questionDecoder

questionDecoder : Json.Decoder Question
questionDecoder =
  Json.object2
        Question
          ("title" := Json.string)
          ("content" := Json.string)

fetchData : Cmd Msg
fetchData =
  let
    url = "http://localhost:3000/api/questions"
  in
    Task.perform FetchFail FetchDone (Http.get questionsDecoder url)

--INIT

init : ( Model, Cmd Msg )
init =
  ( initialModel
  , fetchData )

--UPDATE

type Msg = NoOp
    | FetchData
    | FetchDone (List Question)
    | FetchFail Http.Error

update : Msg -> Model -> (Model, Cmd Msg)
update message model =
  case message of
    NoOp ->
      ( model, Cmd.none )
    FetchData ->
      ( model, fetchData)
    FetchDone results ->
      ( { model | questions = results }
      , Cmd.none )
    FetchFail error ->
      ( model, Cmd.none )

-- VIEW

questionView : Model -> Question -> Html Msg
questionView model question =
  div [ ]
    [ h3 [  ] [text question.title]
    , h5 [  ] [text question.content]
    ]

questionsListView : Model -> Html Msg
questionsListView model =
  ul [ ]
    (model.questions |> List.map (questionView model))

view : Model -> Html Msg
view model =
  div [ ]
    [ h1 [  ] [text "SLACK OVERFLOW"]
    , questionsListView initialModel
    ]

感谢您的帮助！

Answer 1

您的view似乎总是通过initialModel：

view : Model -> Html Msg
view model =
  div [ ]
    [ h1 [  ] [text "SLACK OVERFLOW"]
    , questionsListView initialModel
    ]

我想你想把你收到的model作为参数：

view : Model -> Html Msg
view model =
    div [ ]
        [ h1 [  ] [text "SLACK OVERFLOW"]
        , questionsListView model
        ]

Elm 0.17 - JSON数据无法在视图中呈现

1 个答案: