Receiving data in php via AJAX (inside WordPress)

I have a php function that needs to receive data via AJAX.

This is my code:

Javascript

<script type='text/javascript'>

    jQuery(document).ready(function() {

        jQuery("#fetch_data_button").click(function() {

            searchstring =  "My search text";
                                    
            jQuery.ajax({
                type: "POST",
                url: "admin-ajax.php",
                data: {         
                    action: 'fetch_data', 
                    _ajax_nonce: '<?php echo $nonce; ?>',
                    data: searchstring
                }
            });
            return false;                   
        });                                         
    });
    
</script>

php

add_action( 'wp_ajax_fetch_data', 'fetch_data_fn' );

function fetch_data_fn() {

    $searchstring = $_POST['searchstring'];
    // why is $searchstring empty ... ?

    die(); 
}

The issue is that the searchstring from the AJAX call is not received inside the php function (the received string is empty). Can anybody help me?

Answer

well your main problem is that none of the data you are sending via ajax is named “searchstring”. You have a property named “data” that holds the value of a variable named “searchstring”. so you’d want to test $_POST['data'] in your PHP instead.

I am also a little worroed about you trying to use PHP in your javascript code. It’s usually a red flag, and there is likely a better way of doing what you are trying to accomplish there.