Update MySQL query so that it functions again

Question

I've inherited an old WordPress site that my customer doesn't want to be rebuilt. It has an old MySQL query in the functions.php of the theme that is supposed to put a category image with the category. Over time of course, WordPress has been updated and the query doesn't work any more. I'm hoping someone can help advise how I can update this. The code is:

function catImg($catId){

$data = mysql_fetch_object(mysql_query('SELECT * FROM `wp_ig_caticons` WHERE `cat_id` = "'. $catId .'"'));

if($data->icon){
echo '<img height="158" width="121" title="" alt="skyway" class="attachment-post-thumbnail wp-post-image" src="'. site_url() .'/'. $data->icon .'"/>';
}
else{
echo '<img height="158" width="121" alt="no-image" class="attachment-post-thumbnail wp-post-image" src="'. site_url() .'/wp-content/themes/sky-way/images/no-image.jpg"/>';
}
}

Thank you in advance

Answer 1

mysql_fetch_object() was deprecated in PHP 5.5 and fully removed in PHP 7.0, which is probably why it no longer works for you. It's always better to use WP functions - often they are wrappers for something in PHP (or elsewhere), but by using the WP wrapper version, it usually protects you from deprecation (since the WP method can be updated to accommodate the new scripting language changes) - that way your core code wouldn't need to change.

Try using the $wpdb->get_row(). It's pretty much the same as what you have, but more "WordPressy":

function catImg( $catId ){

    global $wpdb;

    $data = $wpdb->get_row( $wpdb->prepare( 'SELECT * FROM `' . $wpdb->prefix . 'ig_caticons` WHERE `cat_id` =  %d', absint( $catId ) ) );

    if ( $data->icon ) {
        echo '<img height="158" width="121" title="" alt="skyway" class="attachment-post-thumbnail wp-post-image" src="'. esc_url( site_url( esc_attr( $data->icon ) ) ) . '"/>';
    } else {
        echo '<img height="158" width="121" alt="no-image" class="attachment-post-thumbnail wp-post-image" src="'. site_url( '/wp-content/themes/sky-way/images/no-image.jpg' ) . '"/>';
    }
}