试图让 elm 端口工作以维持会话。
在 index.html 中,脚本包含以下监听器:
window.addEventListener("load", function(event) {
app.ports.onSessionChange.send(localStorage.session);
}, false);
localStorage.session
看起来像这样(它会一直留在那里,直到我退出):
{"email":"user@fake.com","token":"eyJhbG...","user_id":1,"handle":"me"}
中的定义Ports.elm
是:
port onSessionChange : (Value -> msg) -> Sub msg
此端口连接到Main.elm
此处(如果我忘记包含以下一些定义,请告诉我):
subscriptions : Model -> Sub Msg
subscriptions model =
Ports.onSessionChange sessionChange
sessionChange : Json.Decode.Value -> Msg
sessionChange value =
let
result =
Json.Decode.decodeValue sessionDecoder value
in
case result of
Ok sess ->
SetSession (Just sess)
Err err ->
SetSession Nothing
...
type alias Session =
{ email : String
, token : String
, user_id : Int
, handle : String
}
...
import Json.Decode as Decode exposing (..)
import Json.Decode.Pipeline as Pipeline exposing (decode, required)
sessionDecoder : Decode.Decoder Session
sessionDecoder =
Pipeline.decode Session
|> Pipeline.required "email" Decode.string
|> Pipeline.required "token" Decode.string
|> Pipeline.required "user_id" Decode.int
|> Pipeline.required "handle" Decode.string
...
type Msg
= NoOp
| SetSession (Maybe Session)
...
update msg model =
case msg of
SetSession session ->
case Debug.log "session = " session of
Just sess ->
({ model | session = sess } , Cmd.none)
Nothing ->
(model, Cmd.none)
Debug.log "session"
页面加载时显示Nothing
在控制台中,因此 JS 正在与 elm 对话,但解码器似乎失败了。有任何想法吗?