Android failed GET retrofit API call to server

Question

I am working on a Android project. I am using retrofit to call API's. So I am doing an API call to get the list of courses associated with certificate.

Response from the server get (BASE_URL/certificates/1) is:

{
  "id": 1,
  "name": "Arts-certificate",
  "authorized_by": "priya",
  "created_by": "self",
  "created_by_id": "1",
  "description": "awarded to the best",
  "doc_url": "http://f8rentals.com/wp-content/uploads/2015/03/IMG_0067ft.jpg?189db0",
  "category_id": "2",
  "cateogory": "Arts",
  "courses": [
    {
      "id": 1,
      "course_id": "CRSXQHGZ0SCTLhklhk6JL",
      "number_of_sessions": 1,
      "created_at": "2015-12-16T07:10:37.000+00:00",
      "updated_at": "2015-12-16T07:10:37.000+00:00",
      "tags": null
    },
    {
      "id": 1,
      "course_id": "CRSXQHGZ0SCTLhklhk6JL",
      "number_of_sessions": 1,
      "created_at": "2015-12-16T07:10:37.000+00:00",
      "updated_at": "2015-12-16T07:10:37.000+00:00",
      "tags": null
    }
    .
    .
    .
    .
  ]
}

I have lists of certificates and required action is, upon clicking the certificate, it should take to new fragment which have all the courses associated with this certificate (on which click is made). For this I make the above API call.

Problem is when I click the first certificate in the list it goes to next fragment and list all the courses. But when I click any other certificate, it shows the blank fragment. When I Debug the code, in the fetchCourses() CoursesListOfCertificatesFragment.java , the onFailure() function is called.

Workflow is CertificateFragment is the class which lists all the certificates. And on click, CertificateClickListner() in CertificateFragment, is triggered and in turn launches CoursesListOfCertificatesFragment with certificate object passed in constructor of this fragment. Here I make the API call GET (BASE_URL/certificates/1).

This is in fetchCourses() in CoursesListOfCertificatesFragment. But except for 1st certificate, onFailure() method is called.

Any help is appreciated..... If any other information is required please ask.

Thanks.

Below are the relevant classes listed:

CoursesListOfCertificatesFragment.java

package com.localjini.learner.fragments;

import android.os.Bundle;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ProgressBar;
import android.widget.TextView;

import com.localjini.learner.R;
import com.localjini.learner.adapters.CourseListingRVAdapter;
import com.localjini.learner.api.RestClient;
import com.localjini.learner.main.HomeActivity;
import com.localjini.learner.models.Certificates;
import com.localjini.learner.models.Course;
import com.localjini.learner.models.CoursesResponse;
import com.localjini.learner.models.GetCertificateResponse;
import com.localjini.learner.utils.LogUtils;
import com.localjini.learner.utils.UIHelper;

import java.util.List;

import butterknife.Bind;
import butterknife.ButterKnife;
import retrofit.Call;
import retrofit.Callback;
import retrofit.Response;
import retrofit.Retrofit;


public class CoursesListOfCertificatesFragment extends BaseFragment {

    @Bind(R.id.tv_category)
    TextView tvCategory;
    @Bind(R.id.tv_sort_filter)
    TextView tvSortFilter;
    @Bind(R.id.pb_course_listing)
    ProgressBar pbCourseListing;
    @Bind(R.id.rv_course_listing)
    RecyclerView rvCourseListing;

    public UIHelper uiHelper;
    List<Course> courses;

    private Certificates certificate;
    private int certificate_id;

    public CoursesListOfCertificatesFragment(){

    }

    private CourseListingRVAdapter.CourseClickListener listener = new CourseListingRVAdapter.CourseClickListener() {

        @Override
        public void onCourseClicked(Course course) {
            interactionListener.launchCourseDetailFragment();
        }
    };

    public CoursesListOfCertificatesFragment(Certificates certificate){
        this.certificate = certificate;
        this.certificate_id = certificate.getId();
    }

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

    }

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        if (root == null) {
            root = (ViewGroup) inflater.inflate(R.layout.fragment_course_listing, container, false);

            ButterKnife.bind(this, root);

            initInstances();

            fetchCourses();
        }


        return root;
    }

    private void initInstances() {
        uiHelper = new UIHelper(getActivity());

        ((HomeActivity) getActivity()).getSupportActionBar().setHomeButtonEnabled(true);
        ((HomeActivity) getActivity()).getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        ((HomeActivity) getActivity()).getSupportActionBar().setTitle("");

        rvCourseListing.setItemAnimator(new DefaultItemAnimator());
        rvCourseListing.setLayoutManager(new LinearLayoutManager(getActivity()));
        rvCourseListing.setHasFixedSize(true);
    }

    private void fetchCourses() {
        Call<GetCertificateResponse> call = RestClient.getCMSServiceInstance().getCertificateById(certificate_id);
        call.enqueue(new Callback<GetCertificateResponse>() {
            @Override
            public void onResponse(Response<GetCertificateResponse> response, Retrofit retrofit) {

                if (response != null) {
                    GetCertificateResponse resp = response.body();

                    if (resp != null) {
                        showCourses(resp.getCourses());
                    } else {
                        uiHelper.showToast("response contain null data");
                    }
                }
            }

            @Override
            public void onFailure(Throwable t) {
                LogUtils.d("coursesFailed", t.getMessage());
            }
        });

    }

    private void showCourses(List<Course> courses) {
        if(courses != null) {
            CourseListingRVAdapter courseListingRVAdapter = new CourseListingRVAdapter(getActivity(), courses);
            courseListingRVAdapter.setCourseClickListener(listener);
            rvCourseListing.setAdapter(courseListingRVAdapter);
        }
    }

    public FragmentId getFragmentId() {
        return FragmentId.COURSE_LISTING_FRAGMENT;
    }

}

CertificateFragment.java

public class CertificateFragment extends BaseFragment {

    private static final String ARG_PARAM1 = "param1";
    private static final String ARG_PARAM2 = "param2";
    //protected ViewGroup root;
    protected Context context;
    @Bind(R.id.rv_Certificates) RecyclerView rvCertificates;

    private CertificateRVAdapter.CertificateClickListener listener = new CertificateRVAdapter.CertificateClickListener() {

        @Override
        public void onCertificateClicked(Certificates certificate) {
            Toast.makeText(getActivity(), certificate.getName() +" Clicked", Toast.LENGTH_SHORT).show();
            //interactionListener.launchCourseListingFragment();
            interactionListener.launchCoursesListOfCertificatesFragment(certificate);
        }
    };


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        if(root==null) {

            root = (ViewGroup) inflater.inflate(R.layout.fragment_certificate, container, false);
            ButterKnife.bind(this, root);

            initInstances();
            getCertificates();
        }
        return root;
    }
//    rvCourseListing.setItemAnimator(new DefaultItemAnimator());
//    rvCourseListing.setLayoutManager(new LinearLayoutManager(getActivity()));
//    rvCourseListing.setHasFixedSize(true);
//

    private void initInstances() {
        //uiHelper = new UIHelper(getActivity());

        ((HomeActivity) getActivity()).getSupportActionBar().setHomeButtonEnabled(true);
        ((HomeActivity) getActivity()).getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        ((HomeActivity) getActivity()).getSupportActionBar().setTitle("");

        rvCertificates.setItemAnimator(new DefaultItemAnimator());
        rvCertificates.setLayoutManager(new LinearLayoutManager(getActivity()));
        rvCertificates.setHasFixedSize(true);
    }

    private void getCertificates() {

        Call<AllCertificateResponse> call = RestClient.getCMSServiceInstance().getCertificates();

        call.enqueue(new Callback<AllCertificateResponse>() {
            @Override
            public void onResponse(Response<AllCertificateResponse> response, Retrofit retrofit) {
                if (response.isSuccess()) {
                    //com.squareup.okhttp.Response raw = response.body().raw();

                    List<Certificates> certificates = response.body().getCertificates();
                    if (certificates != null)
                        showCertificates(certificates);

                    Toast.makeText(getActivity(), "Success in getting certificates", Toast.LENGTH_SHORT).show();
                } else {
                    Log.d("CERT", "response is failure");
                }
            }

            @Override
            public void onFailure(Throwable t) {
                Toast.makeText(getActivity(), "Failure", Toast.LENGTH_SHORT).show();
            }

        });
    }

    public void showCertificates(List<Certificates> certificates){

        CertificateRVAdapter adapter = new CertificateRVAdapter(getActivity(), certificates);
        adapter.setCertificateClickListener(listener);
        rvCertificates.setAdapter(adapter);
    }

    public FragmentId getFragmentId() {
        return FragmentId.COURSE_LISTING_FRAGMENT;
    }

}

Answer 1

I fixed the problem. Turns out server was giving the wrong response( it is still in testing phase). I was expecting array of strings. While for 1st certificate, all courses had array of strings, but for 2nd onward, all had string values instead of arrays.