[SOLVED] Retrofit - @Body parameters cannot be used with form or multi-part encoding

Retrofit - @Body parameters cannot be used with form or multi-part encoding

I m trying to make a request in which I want to include a Header , a form-urlencoded field and a json body. My Retrofit interface is as follows

@FormUrlEncoded
@POST("/api/register")
Observable<RegisterResponse> register(
    @Header("Authorization") String authorization, 
    @Field("grant_type") String grantType, 
    @Body RegisterBody body
);

When I make this request I get back exception @Body parameters cannot be used with form or multi-part encoding.
I have also tried with the @Multipart annotation:

@Multipart
@FormUrlEncoded
@POST("/api/register")
Observable<RegisterResponse> register(
    @Header("Authorization") String authorization, 
    @Part("grant_type") TypedString grantType, 
    @Body RegisterBody body
);

and I get an IllegalArgumentException and only one encoding annotation is allowed.

Solution

This post pointed me to the right direction https://stackoverflow.com/a/21423093/1446856. I attached everything in the body and send it as a TypedInput.
So the interface looks something like this

@POST("/api/register")
@Headers({ "Content-Type: application/json;charset=UTF-8"})
Observable<RegisterResponse> register(
    @Header("Authorization") String authorization,
    @Body TypedInput body
);

and the body looks something like this

String bodyString = jsonBody + "?grant_type=" + 
    grantType + "&scope=" + scope;
TypedInput requestBody = new TypedByteArray(
    "application/json", bodyString.getBytes(Charset.forName("UTF-8")));