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Token HTTP Authentication in Elm
import Html.App as Html
import Html exposing (..)
import Html.Events exposing (..)
import Task
import Http
import Json.Decode as Json exposing ((:=))
-- Model
type alias Model =
{ token : Token
, pendingRequests : List (String -> Task.Task Never Msg)
, ip : String
}
type Token
= Valid String
| Invalid
| Refreshing
init : ( Model, Cmd Msg )
init =
( Model (Valid "expired") [] "no ip", Cmd.none )
-- Update
type Msg
= Fetch
| FetchFailure Http.Error
| SaveIp String
| SaveRequest (String -> Task.Task Never Msg)
| RefreshTokenFailed Never
| UpdateToken String
| SendPendingRequests ()
attemptWithToken : Token -> (x -> msg) -> (a -> msg) -> (String -> Task.Task x a) -> Cmd msg
attemptWithToken token failureMsg successMsg requestWithoutToken =
case token of
Invalid ->
Cmd.none
Refreshing ->
Cmd.none
Valid token ->
Task.perform failureMsg successMsg (requestWithoutToken token)
update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
case msg of
Fetch ->
( model, attemptWithToken model.token FetchFailure SaveIp fetchIp )
FetchFailure error ->
( { model | token = Refreshing }, Task.perform RefreshTokenFailed UpdateToken (Task.succeed "valid") )
SaveIp ip ->
( { model | ip = ip }, Cmd.none )
-- Token Logic
SaveRequest request ->
( { model | pendingRequests = request :: model.pendingRequests }, Cmd.none )
RefreshTokenFailed error ->
( model, Cmd.none )
UpdateToken newToken ->
( { model | token = Valid newToken }, Task.perform SendPendingRequests SendPendingRequests (Task.succeed ()) )
SendPendingRequests _ ->
( model, Cmd.none )
-- View
view : Model -> Html Msg
view model =
div []
[ button [ onClick Fetch ] [ text "send request" ]
, text model.ip
]
-- Request
fetchIp : String -> Task.Task Http.Error String
fetchIp token =
if token == "expired" then
Http.get ("ip" := Json.string) ("http://thisfails" ++ token)
else
Http.get ("ip" := Json.string) ("http://jsonip.com?token=" ++ token)
-- Main
main : Program Never
main =
Html.program
{ init = init
, update = update
, view = view
, subscriptions = \_ -> Sub.none
}
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