Trigger PHP function by clicking HTML link

Question

Is it possible to trigger a PHP function by just clicking a link? Or should I stick with the form submit method? If clicking the link will work, where should the link refer to?

Here is a sample code:

<?php
    session_start();
    function listMe($username){
        $username = mysql_real_escape_string($username);
        $query = mysql_query("INSERT INTO List (Usernames) VALUES ('$username')") or die(mysql_error());
    }
?>

<html>
    <head>
        <title>SAMPLE</title>
    </head>
    <body>
        <a href="**__???___**">Add my username to the list</a>
        <?php 
            listMe($_SESSION['Username']); 
        ?>
    </body>
</html>

Maybe someone can point me in the right direction. Thanks!

Zack Zatkin-Gold · Accepted Answer · 2011-12-29 00:02:08Z

11

You can do this by means of loading the entire page over again by the use of form submission, or by loading specific page contents directly into the page without needing to go from page to page. The second method is called "AJAX" (Asynchoronous Javascript and XML). Here are two examples, one of each specified.

Form submission approach

form.php

<?php
function get_users(){
}
if(isset($_GET['get_users']))
{
    get_users();
}
?>
...
<form method="get">
    <input type="hidden" name="get_users">
    <input type="submit">
</form>

AJAX approach

ajax_file.php

<?php
function call_me(){
    // your php code
}
call_me();
?>

form.html

<html>
<head>
<script type="text/javascript">
function loadXMLDoc()
{
    var xmlhttp;
    if (window.XMLHttpRequest)
    {
        xmlhttp = new XMLHttpRequest();
    }
    else
    {
        xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
    }
    xmlhttp.onreadystatechange = function()
    {
        if(xmlhttp.readyState == 4 && xmlhttp.status == 200)
        {
            // do something if the page loaded successfully
        }
    }
    xmlhttp.open("GET","ajax_file.php",true);
    xmlhttp.send();
}
</script>
</head>
<body>
<a href="#" onclick="loadXMLDoc()">click to call function</a>
</body>
</html>

edited Dec 29, 2011 at 0:02

answered Dec 28, 2011 at 23:53

Zack Zatkin-Gold

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2 Comments

fart-y-goer Over a year ago

I'm tweaking your code, I'll feedback once it worked. btw I think I can use your code for other cases.. Thank you!

Zack Zatkin-Gold Over a year ago

No problem. I left out little pieces that I assume you could fill in yourself, and to prevent myself from writing the whole application for you.

powerbuoy · Accepted Answer · 2011-12-28 23:43:59Z

8

HTML

<a href="?list_me">list me</a>

PHP

<?php
if (isset($_GET['list_me'])) listMe();

answered Dec 28, 2011 at 23:43

powerbuoy

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1 Comment

Nguai al Over a year ago

i think you are missing some code in your anchor. you need href="xyz.php?list_me='me'

gotofritz · Accepted Answer · 2022-09-29 22:22:48Z

8

(EDIT although this works, it's a bad idea as it is. One should never read from $_GET without sanitising it first)

You can pass it as a query parameter of the link. http://example.com/?command=listMe&username=tom However that way everybody will be able to run the function by loading that URL

<a href="http://example.com/?command=listMe&">List me</a>

and in the PHP

<?php
if( isset($_GET['list_me']) && isset($_SESSION['Username'] ) ){
   listMe( $_SESSION['Username'] );
}
?>

edited Sep 29, 2022 at 22:22

answered Dec 28, 2011 at 23:49

gotofritz

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Comments

Dominic Green · Accepted Answer · 2011-12-28 23:46:32Z

3

To trigger a function on link click with php the only way I know would be to append a param in the url of the link and then listen for that

<a href="?function">Add my username to the list</a>

Then check for link

if (isset($_GET['function'])){
      runFunction();
}

This is because php is a server side technology if you want to fire something without refreshing the page you would need to look at something like javascript

answered Dec 28, 2011 at 23:46

Dominic Green

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Comments

Petter Friberg · Accepted Answer · 2016-11-10 22:22:21Z

0

I found this code in a plugin, they have user a foreach look to trigger the action:

$actions = unset($meta[$key]);
foreach ( $actions as $action => $value ) {
    echo '<li><a href="' . esc_url( $value['url'] ) . '" class="my-action-' . $action . '">' . '<i class="fa fa-times"></i></a></li>';
}

edited Nov 10, 2016 at 22:22

Petter Friberg

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answered Nov 10, 2016 at 22:16

jilt

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