Re: [elm-discuss] http request: How to access the whole response

[germain]

Hi William,
 

> The error type has to be "Maybe" because we could hit a network error 
> before we get a response
>

Yes,the Task.andThen error returned value could be with or without 
response! 
The compiler forces us to take into consideration both scenarios => the 
error returned value (what value it could ever be, with or without 
response) should be of identical Type: Maybe Http.Response, Http.Error
We won't later on have some kind of JS troubles like "response is 
undefined" :) 

In the code below you will see that I have used pattern matching to grab 
the relevant fields of the response. It looks natural to me as I am an 
aficionado of Elixir.

I think this post is almost over now. Til now I have hardcoded the body of 
the send request. I should make a form :)  Thanks again !


-- MODEL

type alias Model =
{ error : String
, responseValue: Seat
, responseWithoutValue: responseWithoutValue
 }

type alias Seat =
  { seatNo : Int
  , occupied : Bool
  , id : Int
  }

type alias ResponseWithoutValue =
{ status : Int
, statusText : String
, headers : Dict.Dict String String
, url : String
}


-- JSON DECODER

seatDecoder : JsonDecode.Decoder Seat
seatDecoder =
  let
seat =
  JsonDecode.object3 Seat
("seatNo" := JsonDecode.int)
("occupied" := JsonDecode.bool)
("id" := JsonDecode.int)
  in
-- I use phoenix as backend which wraps the body of the response in a 
Json "data" field 
"data"  := seat


-- UPDATE 

type Msg
= CreateSeat
| PostSucceed (Http.Response, Seat)
| PostFail ( Maybe Http.Response, Http.Error )


update : Msg -> Model -> (Model, Cmd Msg)
update msg model =
case msg of
CreateSeat ->
  (model, postCommand )

PostSucceed  ( { status, statusText, headers, url }, decodedValue ) ->
  (
  { model
| postData = decodedValue
, responseWithoutValue = { status =  status, statusText = 
 statusText, headers =  headers, url =  url }
  }
  , Cmd.none
  )

PostFail errorMessage ->
  ( {  model | error = (toString errorMessage) }, Cmd.none)


Le mercredi 22 juin 2016 00:33:05 UTC+8, William Casarin a écrit :
>
> Hey germain, 
>
> On Mon, Jun 20, 2016 at 11:23 PM, germain  > wrote: 
> > IT'S WORK, thank you so much William ~ 
>
> No problem. 
>
> > - Http.fromJson decoder (Task.succeed response) => why do you use 
> > (Task.succeed response) ? And not just give as argument "response"? 
> > Is it connected with `andThen` and its signature  andThen : Task x a -> 
> (a 
> > -> Task x b) -> Task x b where a is "just" the response of the post 
> request 
> > which must be transformed into a Task by using Task.succeed succeed : a 
> -> 
> > Task x a in order to pass it to the fromJson function which requires 
> > fromJson : Decoder a -> Task RawError Response -> Task Error a ? 
>
> Exactly right, you answered your own question. Since we temporarily 
> extracted 
> the response value using `andThen`, we need to wrap it up with succeed 
> again so 
> that fromJson accepts it. Also the second argument to `andThen` is a 
> function 
> that must return a task, and since `decoded` returns a task, it works out. 
>
> The error type has to be "Maybe" because we could hit a network error 
> before we get a response. 
>
> > - Do you know the difference between Task.Task and Platform.Task? 
>
> They're the same. They're aliased to each other. 
>
> Cheers, 
> William 
>
> --- 
> https://jb55.com 
>

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Re: [elm-discuss] http request: How to access the whole response

[William Casarin]

Hey germain,

On Mon, Jun 20, 2016 at 11:23 PM, germain  wrote:
> IT'S WORK, thank you so much William ~

No problem.

> - Http.fromJson decoder (Task.succeed response) => why do you use
> (Task.succeed response) ? And not just give as argument "response"?
> Is it connected with `andThen` and its signature  andThen : Task x a -> (a
> -> Task x b) -> Task x b where a is "just" the response of the post request
> which must be transformed into a Task by using Task.succeed succeed : a ->
> Task x a in order to pass it to the fromJson function which requires
> fromJson : Decoder a -> Task RawError Response -> Task Error a ?

Exactly right, you answered your own question. Since we temporarily extracted
the response value using `andThen`, we need to wrap it up with succeed again so
that fromJson accepts it. Also the second argument to `andThen` is a function
that must return a task, and since `decoded` returns a task, it works out.

The error type has to be "Maybe" because we could hit a network error
before we get a response.

> - Do you know the difference between Task.Task and Platform.Task?

They're the same. They're aliased to each other.

Cheers,
William

---
https://jb55.com

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Re: [elm-discuss] http request: How to access the whole response

[germain]

IT'S WORK, thank you so much William ~ 

BUT I HAVE A FEW MORE QUESTIONS:

- Http.fromJson decoder (Task.succeed response) => why do you use 
(Task.succeed response) ? And not just give as argument "response"?
Is it connected with `andThen` and its signature  andThen 
 : 
Task  x 
a -> (a -> Task 
 x b) -> 
Task  x 
b where a is "just" the response of the post request which must be 
transformed into a Task by using Task.succeed succeed 
 : a 
-> Task  
x a in order to pass it to the fromJson function which requires fromJson 
 : 
Decoder a -> Task RawError 
 
Response 
 
-> Task Error 
 a ?

- Do you know the difference between Task.Task and Platform.Task?

I still have to write the "correct" decoder of the result of the 
Http.fromJson :)

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Re: [elm-discuss] http request: How to access the whole response

[William Casarin]

Hey germain,

On Thu, Jun 16, 2016 at 9:52 AM, germain  wrote:
>
> HOWEVER I just get the value field of the response and nothing else
>
> UnexpectedPayload "Expecting an object with a field named `fakeInt` but
> instead got: {\"data\":{\"seatNo\":100,\"occupied\":true,\"id\":67}}"
>
> What's wrong?

If you're looking to handle UnexpectedPayload messages, you'll need to
include the Response in the error type:


withResponse : JsonDecode.Decoder a
-> Task.Task Http.RawError Http.Response
-> Task.Task (Maybe Http.Response, Http.Error) a
withResponse decoder task =
  let
decoded response = Http.fromJson decoder (Task.succeed response)
  in
-- Task.mapError promoteError task `Task.andThen` decoded
Task.mapError (\rawErr -> (Nothing, promoteError rawErr)) task
`Task.andThen` (\resp -> Task.mapError (\err -> (Just
resp, err)) (decoded resp))


Cheers,
William

---
https://jb55.com

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Re: [elm-discuss] http request: How to access the whole response

[germain]

type alias PostResponse =
  (Http.Response, Int)

type alias Model =
{ error : String
, response:  String
 }


type Msg
= CreateSeat
| PostSucceed PostResponse
| PostFail Http.Error


update : Msg -> Model -> (Model, Cmd Msg)
update msg model =
case msg of
CreateSeat ->
  (model, postCommand )

PostSucceed  response ->
  ( { model | response = (toString response) },  Cmd.none )

PostFail errorMessage ->
  ( {  model | error = (toString errorMessage) }, Cmd.none)
   
post' : String -> Http.Body -> Task.Task RawError Http.Response
-- post' decoder url body =
post' url body =
Http.send Http.defaultSettings
{ verb = "POST"
, headers =[ ("Content-type", "application/json")]
, url = url
, body = body
}
-- |> Http.fromJson decoder


promoteError : RawError -> Error
promoteError rawError =
  case rawError of
  Http.RawTimeout  -> Http.Timeout
  Http.RawNetworkError -> Http.NetworkError

withResponse : JsonDecode.Decoder a -> Task.Task Http.RawError 
Http.Response -> Task.Task Http.Error (Http.Response, a)
withResponse decoder task =
  let
decoded response =
  Task.map (\val -> (response, val)) (Http.fromJson decoder 
(Task.succeed response))
  in
-- Task.mapError promoteError task `Task.andThen` decoded
Task.mapError promoteError task `Task.andThen` decoded

fakeDecoder : JsonDecode.Decoder Int
fakeDecoder =
"fakeInt"  := ( JsonDecode.int )


postCommand : Cmd Msg
postCommand =
  let
body = Http.string """{"seat":{"seat_no": 100, "occupied": true}}"""
url = "http://localhost:4000/api/seats";

  in
post' url body
|> withResponse fakeDecoder
|> Task.perform PostFail PostSucceed

HOWEVER I just get the value field of the response and nothing else

UnexpectedPayload "Expecting an object with a field named `fakeInt` but 
instead got: {\"data\":{\"seatNo\":100,\"occupied\":true,\"id\":67}}"

What's wrong?

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Re: [elm-discuss] http request: How to access the whole response

[germain]

post' : String -> Http.Body -> Task.Task RawError Http.Responsepost' url 
body =Http.send Http.defaultSettings{ verb = "POST", headers =[ 
("Content-type", "application/json")], url = url, body = body}

promoteError : RawError -> ErrorpromoteError rawError =  case rawError of  
Http.RawTimeout  -> Http.Timeout  Http.RawNetworkError -> 
Http.NetworkError
withResponse : JsonDecode.Decoder a -> Task.Task Http.RawError 
Http.Response -> Task.Task Http.Error (Http.Response, a)withResponse 
decoder task =  letdecoded response =  Task.map (\val -> (response, 
val)) (Http.fromJson decoder (Task.succeed response))  inTask.mapError 
promoteError task `Task.andThen` decoded


-- a FAKE decoder to get the UnexpectedPayload message :)
fakeDecoder : JsonDecode.Decoder IntfakeDecoder ="fakeInt"  := ( 
JsonDecode.int )


postCommand : Cmd Msg
postCommand =
  let
body = Http.string """{"seat":{"seat_no": 100, "occupied": true}}"""
url = "http://localhost:4000/api/seats";

  in
post' url body
|> withResponse fakeDecoder
|> Task.perform PostFail PostSucceed

type alias MyResponse =
  (Http.Response, Int)


update : Msg -> Model -> (Model, Cmd Msg)
update msg model =
case msg of
 CreateSeat ->
  (model, postCommand )

  PostSucceed  response ->
  ( { model | response = (toString response) },  Cmd.none )
 
  PostFail errorMessage ->
  ( {  model | error = (toString errorMessage) }, Cmd.none)


And then I got the same result, the value of the Http.Response only :
UnexpectedPayload "Expecting an object with a field named `seatNo` but 
instead got: {\"data\":{\"seatNo\":100,\"occupied\":true,\"id\":62}}"

What's wrong?


Le jeudi 16 juin 2016 01:10:02 UTC+8, William Casarin a écrit :
>
> Hey germain, 
>
> On Wed, Jun 15, 2016 at 8:51 AM, germain  > wrote: 
> > Hello, 
> > [..] 
> > Is it possible to retrieve the whole response, for example to retrieve 
> the 
> > status and the value fields? 
>
> So this is a bit ugly because promoteError is not exposed, but it can 
> be accomplished with `Task.andThen`: 
>
>
> promoteError : RawError -> Error 
> promoteError rawError = case rawError of 
>   RawTimeout  -> Timeout 
>   RawNetworkError -> NetworkError 
>
> withResponse : Decoder a -> Task RawError Response -> Task Error 
> (Response, a) 
> withResponse decoder task = 
>   let 
>   decoded resp = Task.map (\val -> (resp, val)) 
>   (Http.fromJson decoder (Task.succeed 
> resp)) 
>   in 
>   Task.mapError promoteError task `Task.andThen` decoded 
>
>
> Cheers, 
> William 
>
> --- 
> https://jb55.com 
>

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Re: [elm-discuss] http request: How to access the whole response

[germain]

post' : String -> Http.Body -> Task.Task RawError Http.Responsepost' url 
body =Http.send Http.defaultSettings{ verb = "POST", headers =[ 
("Content-type", "application/json")], url = url, body = body}

promoteError : RawError -> ErrorpromoteError rawError =  case rawError of  
Http.RawTimeout  -> Http.Timeout  Http.RawNetworkError -> 
Http.NetworkError
withResponse : JsonDecode.Decoder a -> Task.Task Http.RawError 
Http.Response -> Task.Task Http.Error (Http.Response, a)withResponse 
decoder task =  letdecoded response =  Task.map (\val -> (response, 
val)) (Http.fromJson decoder (Task.succeed response))  inTask.mapError 
promoteError task `Task.andThen` decoded


-- a FAKE decoder to get the UnexpectedPayload message :)
fakeInt : JsonDecode.Decoder IntfakeInt ="fakeInt"  := ( JsonDecode.int 
)


postCommand : Cmd Msg
postCommand =
  let
body = Http.string """{"seat":{"seat_no": 100, "occupied": true}}"""
url = "http://localhost:4000/api/seats";

  in
post' url body
|> withResponse statusAndValueDecoder
|> Task.perform PostFail PostSucceed

type alias MyResponse =
  (Http.Response, Int)


update : Msg -> Model -> (Model, Cmd Msg)
update msg model =
case msg of
 CreateSeat ->
  (model, postCommand )

  PostSucceed  response ->
  ( { model | response = (toString response) },  Cmd.none )
 
  PostFail errorMessage ->
  ( {  model | error = (toString errorMessage) }, Cmd.none)


And then I got the same result, the value of the Http.Response only :
UnexpectedPayload "Expecting an object with a field named `seatNo` but 
instead got: {\"data\":{\"seatNo\":100,\"occupied\":true,\"id\":62}}"

What's wrong?


>

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Re: [elm-discuss] http request: How to access the whole response

[William Casarin]

Hey germain,

On Wed, Jun 15, 2016 at 8:51 AM, germain  wrote:
> Hello,
> [..]
> Is it possible to retrieve the whole response, for example to retrieve the
> status and the value fields?

So this is a bit ugly because promoteError is not exposed, but it can
be accomplished with `Task.andThen`:


promoteError : RawError -> Error
promoteError rawError = case rawError of
  RawTimeout  -> Timeout
  RawNetworkError -> NetworkError

withResponse : Decoder a -> Task RawError Response -> Task Error
(Response, a)
withResponse decoder task =
  let
  decoded resp = Task.map (\val -> (resp, val))
  (Http.fromJson decoder (Task.succeed resp))
  in
  Task.mapError promoteError task `Task.andThen` decoded


Cheers,
William

---
https://jb55.com

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