php not showing variable from AJAX

Question

I am trying to post a variable from javascript to the same php page. Here is the code:

<html>
    <head>
        <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
        <script src="https://ajax.googleapis.com/ajax/libs/jqueryui/1.11.3/jquery-ui.min.js"></script>
    </head>
    <body>

    <?php echo 'Result is '; if (isset($_GET['testing'])) { echo $_GET['testing']; } ?>
    <?php $thisPage = "http://$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]"; ?>

    <script>
      $(document).ready(function() {
        $('#testing123').on('change',function () {
            var testing = "confirmed";
            $.ajax({  
                type: "GET",  
                url: "<?php echo $thisPage; ?>",  
                data: testing,
                success: function() { $('#showresult').html("success"); } 
            })
        });
      });
    </script>

    <form>
      <select id="testing123">
        <option value="1">1</option>
        <option value="2">2</option>
        <option value="3">3</option>
      </select>
    </form>

    <div id="showresult"></div>

    </body>
</html>

I have also tried using POST but doesn't pick up in php. Also tried having a separate php file and using include_once() and still doesn't work.

Am I missing a file to load in?

Well, do you understand that URL params have key and value? You did not pass both key and value. You can use data: { testing: testing }, — Regent
– Regent, Commented Apr 17, 2015 at 9:56
Yep, also tried data: { testing: testing }, and still cannot get php to echo back the variable. — Ian Fraser
– Ian Fraser, Commented Apr 17, 2015 at 10:07
apart from the data send problem, why are you sure that the PHP part doesn't work? you are not showing the result in your success function of the call, just a static string. — cypherabe
– cypherabe, Commented Apr 17, 2015 at 10:11

jeroen · Accepted Answer · 2015-04-17 10:11:08Z

7

The problem is that you are sending a string that is not a key-value pair. You can send a string (that is what happens behind the screens anyway) but it needs to be a valid query string consisting of key - value pairs that are correctly encoded.

It is easier to send an object and let jQuery take care of the encoding:

    $('#testing123').on('change',function () {
        var testing = "confirmed";
        $.ajax({  
            type: "GET",  
            url: "<?php echo $thisPage; ?>",  
            data: testing,
            success: function() { $('#showresult').html("success"); } 
        })
    });

Would become something like:

    $('#testing123').on('change',function () {
        // send key - value pairs
        var testing = {'testing': "confirmed"};
        $.ajax({  
            type: "GET",  
            url: "<?php echo $thisPage; ?>",  
            data: testing,
            success: function() { $('#showresult').html("success"); } 
        })
    });

Edit: To get the results of your php script back on your page, you need to use the variable that is passed to the success function:

...
success: function(output_from_php_script) {
            $('#showresult').text(output_from_php_script); 
         }

Also note that posting to the original page that generated the page in an ajax call, is not very convenient: It will return you loads of html (the whole page...) that you don't need.

You'd better write a separate script to process your ajax calls and have that return (echo out...) only what you need.

edited Apr 17, 2015 at 10:11

answered Apr 17, 2015 at 9:56

jeroen

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4 Comments

Ian Fraser Over a year ago

Have updated: var testing = {'testing': "confirmed"}; Still doesn't get through to php.

jeroen Over a year ago

@IanFraser How do you know, are you monitoring the request in the console? Note that you are not doing anything with the output of your php script, you just show a success message.

Ian Fraser Over a year ago

Ah now I have something working, thanks, i'll post updated code.

jeroen Over a year ago

@IanFraser If this solves the current problem, you should probably leave it as it is and post a new question for a new problem.

leopik · Accepted Answer · 2015-04-17 09:57:54Z

0

Even when you happen to succeed with it, you won't really know whether the output was a success since the ajax request will be successful, but the outcome of your PHP might not be. This is probably not what you wanted.
You don't need to use absolute URL, simply use url: "page.php"

What I would suggest you to do is to create a separate php page that only contains <?php echo 'Result is '; if (isset($_GET['testing'])) { echo $_GET['testing']; } ?> and the call this page using ajax.

answered Apr 17, 2015 at 9:57

leopik

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