Retrofit POST Method with Json data got error code 400 : Bad Request

Question

I would like to call a POST Method(Magento REST API) in Retrofit with a JSON data(provide JSON as JsonObject). For that, I call as follow from the postman and work fine for

Answer 1

Change your code to something like this, GsonConverterFactory converts a User object to json itself.

public interface APIService {
    @POST("seq/restapi/checkpassword")
    @Headers({
        "Content-Type: application/json;charset=utf-8",
        "Accept: application/json;charset=utf-8",
        "Cache-Control: max-age=640000"
    })
    Call<Post> savePost(@Body User user);
}

This is User Class:

public class User {
    private String username;
    private String password;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

Answer 2

Try this

1.APIInterface.java

public interface APIInterface {

    /*Login*/
    @POST("users/login")
    Call<UserResponse> savePost(@HeaderMap Map<String, String> header, @Body UserModel loginRequest);

}

2.ApiClient.java

public class ApiClient {

    public static final String BASE_URL = "baseurl";
    private static Retrofit retrofit = null;


    public static Retrofit getClient() {
        if (retrofit == null) {
            HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
            interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
            OkHttpClient client = new OkHttpClient.Builder().addInterceptor(interceptor)
                    .connectTimeout(30, TimeUnit.MINUTES)
                    .readTimeout(30, TimeUnit.MINUTES)
                    .build();

            retrofit = new Retrofit.Builder()
                    .baseUrl(BASE_URL)
                    .client(client)
                    .addConverterFactory(GsonConverterFactory.create())
                    .build();
        }
        return retrofit;
    }

}

3. API call

   public void sendPost(JSONObject jsonObject) {
   
       LoginRequestModel loginRequest = new LoginRequestModel(userName, userPassword);
   
       Map<String, String> header = new HashMap<>();
       header.put("Content-Type", "application/json");
   
       APIInterface appInterface = ApiClient.getClient().create(APIInterface.class);
       System.out.println("Final" + new Gson().toJson(loginRequest));
   
       Call<LoginResponseModel> call = appInterface.savePost(header, loginRequest);
   
       call.enqueue(new Callback<LoginResponseModel>() {
           @Override
           public void onResponse(Call<LoginResponseModel> call, Response<UserModel> response) {
               hideProgressDialog();
   
               if (response.body()!=null) {
   
               } else {
                   Toast.makeText(mContext, "Invalid credentials", Toast.LENGTH_SHORT).show();
               }
   
           }
   
           @Override
           public void onFailure(Call<LoginResponseModel> call, Throwable t) {
               t.printStackTrace();
           }
       });
   

   }

4. Dependencies in Gradle file

   compile 'com.squareup.retrofit2:retrofit:2.3.0'
   compile 'com.google.code.gson:gson:2.8.2'
   compile 'com.squareup.retrofit2:converter-gson:2.3.0'
   compile 'com.squareup.okhttp3:okhttp:3.9.0'
   compile 'com.squareup.okhttp3:logging-interceptor:3.9.0'
   

5.User Model

public class UserModel {

    @SerializedName("usename")
    @Expose
    String userEmail;

    @SerializedName("password")
    @Expose
    String userPassword;

    public UserModel(String userEmail, String userPassword) {
        this.userEmail = userEmail;
        this.userPassword = userPassword;
    }


}

Answer 3

I think the GsonConverterFactory you've set up for all calls converts your JSONObject to json. That's why your call's body may look quite different than you think. This is the result of gson.toJson(new JSONObject()):

{ "nameValuePairs": {} }

Try changing the object you send to this:

public class Credentials {
    private String username;
    private String password;

    ...
}

and then update your call

public interface APIService {

@POST("seq/restapi/checkpassword")
@Headers({
    "Content-Type: application/json;charset=utf-8",
    "Accept: application/json;charset=utf-8",
    "Cache-Control: max-age=640000"
})
Call<Post> savePost(
    @Body Credentials credentials
);}

To ensure your call is correct, call

Gson gson = new Gson();
gson.toJson(new Credentials("test_username", "test_password");