JSON response from PHP script

Question

I am building a registration system for Android. I can add data to the database,which is good. Now I want to add some JSON that will notify the user successful registration or different errors. ie

{
  "status":"success",
  "message":"Successful Registration"

}

or

 {
  "status":"fail",
  "message":"Please enter your name"

}

etc.

Here is my php script.

<?php
   require "init.php";
   $j = new stdClass();
   $name = $_POST['name'];
   $user_name = $_POST['user_name'];
    $user_pass = md5(md5($_POST['user_name']).$_POST['user_pass']);
    if(!$name){
    json_encode(array('status' => 'fail', 'message' => 'Please enter your    
    name'));
   }
   $sql_query = "insert into user_info    
  values('$name','$user_name','$user_pass');";

   if(mysqli_query($con,$sql_query)){

    json_encode(array('status' => 'success', 'message' => 'Successfully 
    registered'));

  }else{

   json_encode(array('status' => 'fail', 'message' => 'Could not   
   register'));
  }



 ?>

With this script I can not detect any JSON repsonse from my Java code,even if I add data successfully.

  private void registerUser(final String name, final String userName,
                          final String password) {
    // Tag used to cancel the request
    String tag_string_req = "req_register";


    StringRequest strReq = new StringRequest(Request.Method.POST,
            "MY_LINK_GOES_HERE", new Response.Listener<String>() {

        @Override
        public void onResponse(String response) {
            Log.d("Response", "Register Response: " + response.toString());

            Toast.makeText(getApplicationContext(), "User successfully registered. Try login now!", Toast.LENGTH_LONG).show();

            // Launch login activity
            Intent intent = new Intent(
                    Register.this,
                    MainActivity.class);
            startActivity(intent);
            finish();
        }
    }, new Response.ErrorListener() {

        @Override
        public void onErrorResponse(VolleyError error) {
            Log.e("Error", "Registration Error: " + error.getMessage());
            Toast.makeText(getApplicationContext(),
                    error.getMessage(), Toast.LENGTH_LONG).show();

        }
    }) {

        @Override
        protected Map<String, String> getParams() {
            // Posting params to register url
            Map<String, String> params = new HashMap<String, String>();
            params.put("name", name);
            params.put("user_name", userName);
            params.put("user_pass", password);

            return params;
        }

    };

    // Adding request to request queue
    AppController.getInstance().addToRequestQueue(strReq, tag_string_req);
}

The line

Log.d("Response", "Register Response: " + response.toString());

gives me nothing.

Any ideas?

Thank you.

Answer 1

First of all, you should mention in your question that you are using the android-volley library, or at least use the tag . Second, if you are trying to parse JSON response, then you should use the JsonObjectRequest instance to do that. Assuming your php script is sending the right JSON , you could try something simple and straight-forward with volley like this:

JsonObjectRequest jsonRequest = new JsonObjectRequest(Request.Method.GET, url, null, new Response.Listener<JSONObject>() {
            @Override
            public void onResponse(JSONObject response) {
                try {
                    response = response.getJSONObject("args");
                    String site = response.getString("site"), network = response.getString("network");
                    View view = findViewById(R.id.activity_layout);
                    Snackbar.make(view, "Site : " + site + " Network : " + network, Snackbar.LENGTH_INDEFINITE).show();
                } catch (JSONException e) {
                    Toast.makeText(getBaseContext(), e.toString(), Toast.LENGTH_LONG).show();
                }
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Toast.makeText(getBaseContext(), "Error Listener", Toast.LENGTH_LONG).show();
            }
        });

        Volley.newRequestQueue(this).add(jsonRequest);

This assumes your JSON is something like this:

{
  "args": {
    "network": "somenetwork", 
    "site": "code"
  }, 
  "args2": {
    ...
  }, 
  "args3": "...", 
  "args4": "..."
}

Now depending on the JSON you are sending, you could try any combination. You could also look into this very useful tutorial . Hope this helps. Let me know if you need more help.

Answer 2

I had encountered the same problemm in my App when i was trying to make a registration. I wanted to check if user registered and if the username is available.

So what i did was:

PHP File:

<?php
try {
    $handler = new PDO('mysql:host=localhost;dbname=database', 'username', 'password');
    $handler->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (Exception $e) {
    echo $e->getMessage();
    die();
}

$username = $_POST['username'];
$password=$_POST['password'];
$email = $_POST['email'];
$dateCreated = $_POST['dateCreated'];
$android_version= $_POST['android_version'];
$api_level = $_POST['api_level'];
$check = $handler->query("SELECT * FROM table WHERE username = '$username'");
$don = array();
     if($check->rowCount() > 0){
          $don = array('result' =>TRUE);
          die();
     }else{
          $don = array('result' =>FALSE);
          $handler->query("INSERT INTO table(id, username, password, email, dateCreated, activated, Android_Version, API_Level) VALUES('', '$username','$password','$email', '$dateCreated', 0, '$android_version', '$api_level')");
     }

echo json_encode($don);
?>

Android:

private class MyInsertDataTask extends AsyncTask {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pDialog = new ProgressDialog(YourActivity.this);
        pDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
        pDialog.setIndeterminate(true);
        pDialog.setMessage(getString(R.string.dialog_rate_data_submit));
        pDialog.setCancelable(false);
        pDialog.setInverseBackgroundForced(true);
        pDialog.show();
    }

    @Override
    protected Boolean doInBackground(String... params) {
        nameValuePairs = new ArrayList<>();
        nameValuePairs.add(new BasicNameValuePair("username", uName));
        nameValuePairs.add(new BasicNameValuePair("password", pass));
        nameValuePairs.add(new BasicNameValuePair("email", email));
        nameValuePairs.add(new BasicNameValuePair("dateCreated", date));
        nameValuePairs.add(new BasicNameValuePair("android_version", release));
        nameValuePairs.add(new BasicNameValuePair("api_level", String.valueOf(sdkVersion)));

        try
        {
            httpClient = new DefaultHttpClient();
            httpPost = new HttpPost(AppConstant.REGISTER_URL);
            httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            response = httpClient.execute(httpPost);
            httpEntity = response.getEntity();
            is = httpEntity.getContent();
            BufferedReader br = new BufferedReader(new InputStreamReader(is));
            StringBuilder result = new StringBuilder();
            String line;
            while ((line = br.readLine()) != null) {
                result.append(line);
            }
            Log.e("Responce", result.toString());
            if (result != null) {
                data = new JSONObject(result.toString());
                usernameExists = data.getBoolean("result");
            }
        }
        catch(Exception e)
        {
            Log.e("Fail 1", e.toString());
        }
        return  usernameExists;
    }
    @Override
    protected void onPostExecute(Boolean aVoid) {
        super.onPostExecute(aVoid);
        pDialog.dismiss();
        if (aVoid){
            Snackbar.with(YourActivity.this).type(SnackbarType.MULTI_LINE).text(getString(R.string.username_exists_message)).color(Color.parseColor(AppConstant.ENABLED_BUTTON_COLOR)).show(getActivity());
        }else {
            Toast.makeText(YourActivity.this, getString(R.string.created_successfully), Toast.LENGTH_SHORT).show();
            Intent intent = new Intent(YourActivity.this, MainActivity.class);
            startActivity(intent);
            YourActivity.this.finish();
        }

    }
}

The result is that if username exists a message pops up saying username already exists otherwise the user registers

Result:

Answer 3

I fixed it! It was a php issue. Here is my solution.

<?php
  require "init.php";
  header('Content-type: application/json');
  $name = $_POST['name'];
  $user_name = $_POST['user_name'];
  $user_pass = md5(md5($_POST['user_name']).$_POST['user_pass']);

        $sql_query = "select * from user_info WHERE user_name  
  ='".mysqli_real_escape_string($con, $user_name)."'";

        $result = mysqli_query($con, $sql_query);   

        $results = mysqli_num_rows($result);

        if ($results){
            $don = array('result' =>"fail","message"=>"Username exists. User               
        a different one");
        }else{

            $sql_query = "insert into user_info  
       values('$name','$user_name','$user_pass');";

            if(mysqli_query($con,$sql_query)){

            $don = array('result' =>"success","message"=>"Successfully  
            registered!Well done");

            }
        }

    echo json_encode($don);

  ?>