Wp return result from sql using AJAX - sql

Question

I need some help i am making a wordpress plug in.
when i try to get some rows from sql thro a AJAX post i will get nothing back.
Even if i try just to return a string it will stays empty.
I Dont get any error .
Thank you so much for helping.
Script:
jQuery(document).ready(function($){
$('.country').change(function(){
alert("asasasas");
var country_id = $(this).val();
alert(country_id);
$.ajax({
cache: false,
type: "POST",
url: "<?php echo plugin_dir_url('brandstof-ajax.php'); ?>",
data: {
action : 'my_action',
id : country_id,
},
success: function(data)
{
alert("sucessss");
alert(data);
console.log(data);
jQuery('.brandstof').html(data);
},
error: function(errorThrown){
alert(errorThrown);
}
});
});
my function:
<?php
add_action('wp_ajax_nopriv_ajax_request', 'my_action');
add_action('wp_ajax_ajax_request', 'my_action');
function my_action() {
$country_id = $_REQUEST['id'];
global $wpdb;
$qbrandstof = $wpdb->get_results("SELECT distinct brandstof FROM autos where jaar='2023'");
foreach($qbrandstof as $brandstof)
{
?>
<option value="<?php echo $brandstof["brandstof"]; ?>"><?php echo $brandstof["brandstof"]; ?></option>
<?php }
die();
}
?>

Answer 1

You should register and localize your script.
Example: -
function my_enqueue() {
wp_enqueue_script( 'ajax-script', plugin_dir_url( __FILE__ ) . '/js/my-ajax-script.js', array('jquery') );
wp_localize_script( 'ajax-script', 'my_ajax_object', array( 'ajax_url' => admin_url( 'admin-ajax.php' ) ) );
}
add_action( 'wp_enqueue_scripts', 'my_enqueue' );
then you can use that javascript object in your script to call the ajax callback function remember to add action in ajax request.
in your case you have used
add_action('wp_ajax_nopriv_ajax_request', 'my_action');
add_action('wp_ajax_ajax_request', 'my_action');.
then action will 'ajax_request'.
try out this code.
jQuery(document).ready(function($){
$('.country').change(function(){
alert("asasasas");
var country_id = $(this).val();
alert(country_id);
$.ajax({
cache: false,
type: "POST",
url: my_ajax_object.ajax_url,
data: {
action : 'ajax_request',
id : country_id,
},
success: function(data)
{
alert("sucessss");
alert(data);
console.log(data);
jQuery('.brandstof').html(data);
},
error: function(errorThrown){
alert(errorThrown);
}
});
})
});
Reference :- https://developer.wordpress.org/reference/hooks/wp_ajax_action/