getting failure Http.error while in browser network shows response - elm

Question

I am exploring ELM and trying to access web api. I followed the this link.
I am able to hit my service and getting the response (Showing in browser network tab), but failure code portion is executing from elm update.
Implementation
---Model
type alias Model =
{
message : String,
}
model:Model
model = {
message = "Hello"
}
--update
postRequest : Http.Request
postRequest =
{ verb = "POST"
, headers =
[("Content-Type", "application/json")
]
, url = "http://xyz/events/list"
, body = Http.string """{ "domainId": 1 }"""
}
getEventList: Cmd Msg
getEventList =
Task.perform Messages.FetchFail Messages.FetchSucceed (Http.fromJson decodeString (Http.send Http.defaultSettings postRequest))
update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
case msg of
Messages.NoOp ->
( model, Cmd.none )
Messages.FetchSucceed xy->
({model| message = "success"},Cmd.none)
Messages.FetchFail _->
({model |message = "fail"} ,Cmd.none)
API response :
{ "message": "", "data": [
{
"eventId": 104,
"title": "private Events",
"description": "abc",
"businessId": 51,
"businessTitle": "VampireDA_Adda",
"startDate": "2016-07-08"
},
{
"eventId": 107,
"title": "Event weekly Midnight",
"description": "xyz",
"businessId": 44,
"businessTitle": "Spanish Scotch",
"startDate": "2016-07-08"
}] }
Please help me, if i have implement any thing wrong.
and also how i can decode json to model (fill model with response json)?

Answer 1

you are probably getting the error because the decoding is not working out. But first try to get used to piping
Http.send Http.defaultSettings postRequest
|> Http.fromJson decodeString
|> Task.perform Messages.FetchFail Messages.FetchSucceed
To decode you need an Elm record
type alias DataItem =
{ eventId: Int
, title: String
, description : String
, businessId : Int
, businessTitle : String
, startDate: String
}
The decoder will then look something like
dataDecoder =
object6 DataItem
("eventId" := int)
("title" := string)
("description" := string)
("businessId" := int)
("businessTitle" := string)
("startDate" := string)
decoder = at ["data"] (list dataDecoder)
Decoders take a bit of getting used to, so I created a site to help you practise: http://simonh1000.github.io/decoder/