Retrieve Json object in android using volley

Question

Trying to get a value from my PHP API, on android, using volley... my API is working fine, returning the value I want, but on my android I can seem to save the value on a variable.

this is my PHP script

<?php

if($_SERVER['REQUEST_METHOD']=='POST'){

$titu = $_POST['titulo'];
$id_use = $_POST['id_user'];
$difi = $_POST['dificuldade'];


$user = "root";
$pass = "";
$host= "localhost";
$dbname="check";

$con = mysqli_connect($host,$user,$pass,$dbname);
$sql="insert into trilhos(titulo,id_user,dificuldade) 
values('".$titu."','".$id_use."','".$difi."');";


$r = mysqli_query($con,$sql);

$id_trilho =mysqli_insert_id($con);

$result = array();
echo json_encode(array("result"=>$id_trilho));

mysqli_close($con);
}

on my android studio, I try to get the value like this, I send 3 values to insert into the database, and then I want to return the id of the row I inserted back to android. I have looked at many answers on StackOverflow but I just can't seem to understand and solve my problem.

public void insert(String titulo, String id_trilho, String dif) {
    url = "http://192.168.1.68/loginsignup/insertTrilho.php?titulo=" + titulo +"&id_user="+ id_trilho+ "&dificuldade=" + dif + "";
    Log.i("Http", "" + url);
    RequestQueue requestQueue = Volley.newRequestQueue(InserirTrilho.this);
    StringRequest stringRequest = new StringRequest(Request.Method.POST, url, new Response.Listener<String>() {
        @Override
        public void onResponse(String response) {
            try {
                JSONObject jsonObject = new JSONObject(response);
                JSONArray jsonArray = jsonObject.getJSONArray("result");
                JSONObject jsonObject1 = jsonArray.getJSONObject(0);
                String id = jsonObject1.getString("id_trilho");
                Toast.makeText(InserirTrilho.this, id, Toast.LENGTH_SHORT).show();


                SharedPreferences shared_id = getSharedPreferences("Mytrilho", Context.MODE_PRIVATE);
                SharedPreferences.Editor editor = shared_id.edit();
                editor.putString("id", id);


                editor.commit();
                Intent intent = new Intent(InserirTrilho.this, MapsActivity.class);
                startActivity(intent);

            } catch (JSONException e) {
                e.printStackTrace();
                Toast.makeText(InserirTrilho.this, "Dados Errados", Toast.LENGTH_SHORT).show();
            }
        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            Log.i("HttpError","erro"+error);
        }

    });
    requestQueue.add(stringRequest);
}

keep getting a thrown exception, can someone help me out, thank you in advance

Answer 1

The issue is, url is a type of Get request but the method is in java request is of type POST so you need to send data as part of the request using as Body so

see how to send a POST request using volley with string body?

---

As commented , Your response is jsonobject not array so use

JSONObject jsonObject = new JSONObject(response);
String id = jsonObject.optString("result");    

instead of

JSONObject jsonObject = new JSONObject(response);
JSONArray jsonArray = jsonObject.getJSONArray("result");
JSONObject jsonObject1 = jsonArray.getJSONObject(0);
String id = jsonObject1.getString("id_trilho");

or to get what you want then use

$result = array();
$result["result"]= array();
array_push($result["result"],array("id_trilho"=>$id_trilho)); // assume $id_trilho =0
echo json_encode($result);
// output {"result":[{"id_trilho":0}]}

---

or simply use

$id_trilho = 0;
$result = array();
array_push($result,array("id_trilho"=>$id_trilho));
echo json_encode($result);
// output [{"id_trilho":0}]
// then use JSONArray jsonArray = new JSONArray(response);
// JSONObject jsonObject1 = jsonArray.getJSONObject(0);
// String id = jsonObject1.getString("id_trilho");