Retrofit2.0.0 beta getting null response body ,response code is 400

Question

I am new to Retrofit.I tried to implement Retrofit 2.0.0 beta in my project. To register a user i tried Retrofit. The METHOD POST is and Content Type is application/x-www-form-urlencoded . I am getting response as 400 but response body is null . I am attaching my code here.

public interface MyApiInterface {
    @Headers("Content-Type: application/x-www-form-urlencoded")
    @FormUrlEncoded
    @POST("/users/register")
    Call<LoginResponse> doRegister(@Field("key") String value, @Field("key")
    String value;
}

public class RestClient {    
    private static Retrofit REST_CLIENT;
    private static MyApiInterface apiService;
    public static String BASE_URL = "http://xx.xxx.xxx.xx:";

    static {
        setupRestClient();
    }

    public static MyApiInterface get() {
        return apiService;
    }

    private static void setupRestClient() {
        REST_CLIENT = new Retrofit.Builder()
                .baseUrl(BASE_URL)

                .addConverterFactory(GsonConverterFactory.create())
                .build();
         apiService =
                 REST_CLIENT.create(MyApiInterface.class);
    }
}


Call<Register> call = RestClient.get().doRegister("xxx",""xxxx);

call.enqueue(new Callback<Register>() {
        @Override
        public void onResponse(Response<Register> response, Retrofit retrofit) {
            int statusCode = response.code();
            LoginResponse user = response.body();
            Log.d("String",statusCode+""+response.body()  );
        }

        @Override
        public void onFailure(Throwable t) {

        }
    });

I am getting response as

{
    status: "failed"
    error_code: "invalid_client"
}  

and my Register class is

public class Register {
   public  String status;
   public String error_code;
}

Answer 1

Your backend seems to does not support default User-Agent header and requires specific one. If you do not provide this header explicitly, I think OkHttp will add default User-Agent which is okhttp/version (not sure about this, could be System.getProperty("http.agent") ).

You should create Interceptor which will add the client header that your server will accept.