How to grab JSON Array and use gson to parse each json object? (Retrofit)

Question

I am returning an array of results with my json Objects, and I am trying to use my customObjectResponse class to pull out each of the fields within each of the objects... th

Answer 1

I ended up just calling in the callback a list of the customObject and it did the job...

new Callback<List<ObjResponse>>() {

Answer 2

I originally had trouble getting an idea of how the OP solved his problem but, after days of debugging I have finally figured out how to solve this issue.

So you essentially have data in the format like so (JSON Array of JSON Objects):

[
    {
      ...
    }
] 

Your class that models the data and contains the getter and setter methods are nothing more than your typical POJO.

public class Person implements Serializable {
    @SerializedName("Exact format of your json field name goes here")
    private String firstName;

    // Getters and Setters....
}

In your interface that contains your RESTful annotations you want to convert your call from:

Before:

public interface APInterface {
    @GET("SOME URL TO YOUR JSON ARRAY")
    Call<Person>(...)
}

After:

public interface APInterface {
    @GET("SOME URL TO YOUR JSON ARRAY")
    Call<List<Person>>(...)
}

In your android activity you want to convert all calls in the form of Call<Person> to Call<List<Person>>

Finally when making the initial asynchronous request call, you will want to convert your callbacks like so.

call.enqueue(new Callback<List<Person>>() {
    @Override
    public void onResponse(Call<List<Person>> call, Response<List<Person>> response) {

        if(response.isSuccessful()){
            List<Person> person = response.body();

           // Can iterate through list and grab Getters from POJO
           for(Person p: person){...}


        } else {
            // Error response...
        }

    }

    @Override
    public void onFailure(Call<List<Person>> call, Throwable t) {...}
});

Hope this helps others whom are lost from the accepted answer above.

Answer 3

This can also work by just passing an array of response objects. So if this is your response object:

public class CustomUserResponse {
    public String firstName;
    public String lastName;
    ...
}

You can use related syntax, depending on how you use the callbacks. Such as:

new Callback<CustomUserResponse[]>(){
    @Override
    public void success(CustomUserResponse[] customUserResponses, Response rawResponse) {

    }

    @Override
    public void failure(RetrofitError error) {

    }
};

OR

public class GetUserCommand implements Callback<CustomUserResponse[]> { ...

Put simply, in every place where you normally replace T with a response class, replace it with an array, instead as in CustomUserResponse[].

---

NOTE: to avoid confusing errors, be sure to also use an array in the Retrofit interface definition:

@POST ( "/users" )
public void listUsers(@Body GetUsersRequest request, Callback<CustomUserResponse[]> callback);

Answer 4

You could try something like this

JSONObject jsonObject = new JSONObject(<your JSON string result>);
JSONArray jsonArray = jsonObject.getJSONArray();

//use GSON to parse
if (jsonArray != null) {
   Gson gson = new Gson();
   ObjResponse[] objResponse = gson.fromJson(jsonArray.toString(), ObjResponse[].class);
   List<ObjResponse> objResponseList = Arrays.asList(objResponse);
}

This should definitely work.