Change Post Class function

Question

I wish to change/remove parts of the automatic post class function that's built in to wordpress, lets say when i make a post, the html code generated looks like this:

<div id="post-106" class="contentmain fullwidth post-106 post type-post status-publish format-standard has-post-thumbnail hentry category-test category-test2 category-test3 category-test4 tag-testingtags1 tag-testingtags2 tag-testingtags3"> 

I wish to remove tags from being in this auto generated code (the tag-testingtags1,2,3), i cannot find which function in wordpress generates the code, anyone care to point me in the right direction? If it is a core file is there a simple way to exclude tags from being inserted into the code using some kind of filter hook in functions.php so i don't have to modify wp core files?

Answer 1

post_class() is a wrapper around get_post_class().

Try the following hook post_class which is fired from get_post_class() within wp-includes/post-template.php:

add_filter('post_class', 'filter_post_class', 10, 3);

function filter_post_class($classes, $class, $post_id) {

    $temp = implode(' ', $classes); 
    $temp = preg_replace('/\s\btag\-\w*\b/i', '', $temp);

    return explode(' ', $temp);

}

Alternatively (RECOMMENED):

add_filter('post_class', 'filter_post_class', 10, 3);

function filter_post_class($classes, $class, $post_id) {

    $classes = array_filter($classes, function($class_name){
       // use !== 0 to ensure we match tag- at begining of string
       return strpos($class_name, 'tag-') !== 0;
    });

    return $classes;

}

Another alternative method, although potentially with risks, is to:

add_filter('get_the_tags', 'filter_get_the_tags');

function filter_get_the_tags() {

    return array();

}

Although with this approach some conditional logic should be considered within the callback.

I say that for the latter because the only other function (in terms of core WP) that calls get_the_tags() is wp-includes/feed.php and inparticular get_the_category_rss().

Answer 2

You can use the post_class filter to modify the output of post classes:

add_filter( 'post_class', 'cyb_post_class' );
function cyb_post_class( $classes ) {

    // Modify the array $classes as you wish
    // For example: remove tag-testingtags1 class
    unset( $classes['tag-testingtags1'] );

    return $classes;
}

The classes with names starting with tag- are generated form the tags associated with the post (post tag taxonomy from core). If you want to auto-remove those classes:

add_filter( 'post_class', 'cyb_post_class', 10, 3 );
function cyb_post_class( $classes, $class, $post_id ) {

    // Get all the tags associated with the post
    $tags = get_the_tags( $post_id );
    if( ! is_wp_error( $tags ) ) {
        foreach( $tags as $tag ) {
            if( isset( $classes['tag-' . $tag->slug] ) ) {
                 unset( $classes['tag-' . $tag->slug] );
            }
        }
    }

    return $classes;
}