Retrofit 错误请求错误：如何做 Retrofit POST 正确的方式

Question

I am having a problem executing a post request using Retrofit. I keep getting the Bad Request error log response.message()

This is the response from Postman GET request to my API:

{
    "data": [
        {
            "id": 7,
            "attributes": {
                "createdAt": "2022-09-14T17:10:38.806Z",
                "updatedAt": "2022-09-14T17:10:38.806Z",
                "publishedAt": "2022-09-14T17:10:38.767Z",
                "title": "This is title",
                "body": "This is body"
            }
        }
    ],
    "meta": {
        "pagination": {
            "page": 1,
            "pageSize": 25,
            "pageCount": 1,
            "total": 1
        }
    }
}

I am able to perform the Retrofit GET and DELETE. The problem comes when am trying to execute a POST. This is the request body that is send using Postman and it is working correctly:

{
    "data": {
        "title": "This is title",
        "body": "This is body"
    }
}

How can I replicate this request body to make POST request using Retrofit using Android Java? Here is the code am using which is retuning Bad request error:

My interface:

public interface Service {

    @FormUrlEncoded
    @POST("api/notes")
    Call<DataResponse> create(
            @Field("title") String title,
            @Field("body") String body
    );

The method I am excuting to Post data:

    private void create(){
        //Call the interface
        crudInterface = RestClient.connection().create(Service.class);
        Call<DataResponse> call = crudInterface.create(title, body);
        call.enqueue(new Callback<DataResponse>() {
            @Override
            public void onResponse(@NonNull Call<DataResponse> call, @NonNull Response<DataResponse> response) {
                Toast toast = Toast.makeText(getApplicationContext(), response.message(), Toast.LENGTH_LONG);
                toast.show();
                Log.e("Response : ", response.message());
                Log.d("Response code: ", String.valueOf(response.code()));

            }

            @Override
            public void onFailure(@NonNull Call<DataResponse> call, @NonNull Throwable t) {
                Toast.makeText(getApplicationContext(), "Gagal menghubungi server : "+t.getMessage(), Toast.LENGTH_LONG).show();
                Log.e("Throw err: ",t.getMessage());
            }
        });
    }

I get this to my logcat:

2022-09-14 20:20:33.153 9649-9649/com.application.strapi_crud E/Response :: Bad Request
2022-09-14 20:20:33.252 9649-9649/com.application.strapi_crud D/Response code :: 400

Answer 1

There is a problem with your service interface. You are posting this json object:

{"title":"yourTitleValue", "body":"yourBodyValue"}

However you should send an object like this:

{
"data": {
    "title": "This is title",
    "body": "This is body"
    }
}

so, there are a few things you can do but I think the most straightforward soultion is to create a data class:

public class Data{
@SerialisedName("title")
private String title;
@SerialisedName("body")
private String body;
//constructors, getters
}

After that, you should change your interface:

public interface Service {

@FormUrlEncoded
@POST("api/notes")
Call<DataResponse> create(@Body Data data);
}

Finally, you should create a Data object and pass it to your function like this:

Call<DataResponse> call = crudInterface.create(new Data("some title", " some 
body"));

If there is not a problem with your DataResponse class, this approch should work.