Http request with options method


I want to fetch a url in the form of “”, below code can work without problem:

fetchIndexCommand : Cmd Msg
fetchIndexCommand =
Http.get “” indexDecoder
|> RemoteData.sendRequest
|> IndexReceived

I am trying to make it another way, make the parameters seperated, as below:

fetchIndexCommand : Cmd Msg
fetchIndexCommand =
indexRequest “” indexDecoder
|> RemoteData.sendRequest
|> IndexReceived

indexRequest : String -> Decoder a -> Http.Request a
indexRequest url decoder =
{ method = “GET”
, headers = []
, url = url
, body = Http.jsonBody indexEncoder
, expect = Http.expectJson decoder
, timeout = Nothing
, withCredentials = False

indexEncoder : Encode.Value
indexEncoder =
[ ( “a”, Encode.string “a” )
, ( “b”, Encode.string “b” )

This will not work, it will return NetworkError of RemoteData, my browser console will show OPTIONS 405 error, as well as on the server end log: REST Method Not Supported (405): Method options not supported at…

The Http.get is also Http.request, why the behaviour is so different? Did I make any mistake?


Is “” the actual url you are fetching? Also what domain is your elm app running on?

This sounds very much like a CORS issue. If the second request is not a “simple request” (see the section on the linked page for details on what that is) then the browser will automatically send an HTTP OPTIONS pre-flight request first to check whether the CORS settings for that site will allow your actual request. From your error message (“Method Not Supported (405): Method options not supported…”) it sounds ike the http server doesn’t support OPTIONS http requests and therefore the CORS pre-flight request fails.


my elm app is on my local machine, fetching from remote. So my server has to accept OPTIONS method.

Thank you. I will try to configure my server


indexRequest is a GET, which does not send a body. You would need to POST (maybe PUT, depending on the use case) in order to send a body. The server will of course need to support these methods and handle parsing the body.


Indeed. So to send a GET request, the parameters have to been added to url as “”, No way to encode seperately?


You can use to encode the query string for a url. If you have a lot of query parameters or a complex use case this may be helpful.


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