I'm trying to send an ajax POST to a php file, however the php file sends a notice of "undefined index", and the php file never seems to receive the value i'm trying to send it. I've been searching for the answer to why this isn't working correctly, so hopefully someone can give me some insight.

My javascript function receives a value from the html, and receives the correct value. (it's "1" in this case)

    function deleteMediaFromDatabase(val)
    {

  $.ajax({ url: 'deleteMediaFromDatabase.php',
         data: {vals : val},
         type: 'post',
         success: function(output) {
                      alert(output);
                  },
          error: function(request, status, error){
            alert("Error: Could not delete");
          }
  });
}

Here is part of my php file that should receive the post:

    <?php

 ini_set("display_errors", "On");
 error_reporting(E_ALL);

    $val = $_POST["vals"];

    // create connection
    $con = mysqli_connect(<stuff you don't care about>);

  error_log($val . ' is the value', 3, "./error.log");

?>

I am, however getting this error message from php:

Notice: Undefined index: vals in /xxx/xxx/htdocs/AdminPanel/deleteMediaFromDatabase.php on line 9

And my javascript always outputs the alert in the error: "Error: Could not delete"

I know this question has been asked and answered many times, however unless I'm skipping over something small, my code, to me, looks correct. (but doesn't it always...)

I'm trying to send an ajax POST to a php file, however the php file sends a notice of "undefined index", and the php file never seems to receive the value i'm trying to send it. I've been searching for the answer to why this isn't working correctly, so hopefully someone can give me some insight.

My javascript function receives a value from the html, and receives the correct value. (it's "1" in this case)

    function deleteMediaFromDatabase(val)
    {

  $.ajax({ url: 'deleteMediaFromDatabase.php',
         data: {vals : val},
         type: 'post',
         success: function(output) {
                      alert(output);
                  },
          error: function(request, status, error){
            alert("Error: Could not delete");
          }
  });
}

Here is part of my php file that should receive the post:

    <?php

 ini_set("display_errors", "On");
 error_reporting(E_ALL);

    $val = $_POST["vals"];

    // create connection
    $con = mysqli_connect(<stuff you don't care about>);

  error_log($val . ' is the value', 3, "./error.log");

?>

I am, however getting this error message from php:

Notice: Undefined index: vals in /xxx/xxx/htdocs/AdminPanel/deleteMediaFromDatabase.php on line 9

And my javascript always outputs the alert in the error: "Error: Could not delete"

I know this question has been asked and answered many times, however unless I'm skipping over something small, my code, to me, looks correct. (but doesn't it always...)

• javascript
• php
• jquery
• ajax

• Have you used any developer tools to ensure the AJAX call is posting the right data? – Machavity ♦ Commented Nov 22, 2013 at 3:54
• Yes, I have used the inspect element feature on google chrome (the network section) which has confirmed what is being sent is the correct data, however the status is listed as (cancelled). Is that what you may have been referring to? – ssrobbi Commented Nov 22, 2013 at 4:07
• When I put in breakpoints and step through my code, it worked perfectly. However, when I take out the breakpoints and run it, it errors out. This is actually being executed inside of a form. when the submit button is being pressed , the form is submitting, which changes the database. Could the fact that this is inside of the form create a race condition? – ssrobbi Commented Nov 22, 2013 at 4:16
• The error message is saying your POST value isn't set. So there is a disconnect somewhere. But you're triggering this with a form submit? – Machavity ♦ Commented Nov 22, 2013 at 4:20
• I'm dynamically adding a table to my html that mimics the tables in the database, putting a delete button next to each row. The value of the delete button is the same as the id in the table. When the button is pressed, it invokes its "onclick='deleteMediaFromDatabase(this.value)'". The value is collected via jquery and sent to the php file via post, so that i can delete a row in the database according to that value, and also delete a file from a server (whose filepath is stored in the database). edited: correct onclick – ssrobbi Commented Nov 22, 2013 at 4:25

5 Answers 5

There is error in syntax of jquery.. You missed out syntax of data. This should be like this-

function deleteMediaFromDatabase(val)
{
$.ajax({ url: 'deleteMediaFromDatabase.php',
     data: {'vals' : val},
     type: 'post',
     dataType:'json',
     success: function(output) {
                  alert(output);
              },
      error: function(request, status, error){
        alert("Error: Could not delete");
      }
});
}

The problem can e from the dataType not being specified or that the dataType specified does not match thus returned by the server.

Explicitely set the dataType, e.g. dataType:'json'

and make sure that your script returns data that is "encoded" in the data type that you chose, e.g. in PHP:

echo json_encode($something);

Instead of:

$val = $_POST["vals"];

use this:

if (isset($_POST['vals']) {
    $val = $_POST['vals'];
}

Change Ajax syntax...

$.ajax({
    type: "POST",
    url: 'deleteMediaFromDatabase.php',
    data: {'vals' : val},//Have u tried this
    success: function(output) {
        alert(output);
    }
    error: function(request, status, error){
            alert("Error: Could not delete");
    }
);

$val = $_POST["vals"];

I got same problem , i tried declaring the variable as global , that solved my problem.

 global $val;
 $val = $_POST["vals"];

and always check isset($_POST["vals"])