Not sure if "sanitizing" is really the correct phrase to use for this but it was the best one I could think of...anyways, here is the problem:

My function works great like so...

// add category id to body & post classes 
function category_id_class($classes) {
    global $post;
    foreach((get_the_category($post->ID)) as $category)
        $classes [] = $category->cat_name;
        return $classes;
add_filter('post_class', 'category_id_class');
add_filter('body_class', 'category_id_class');

That works great until the user inputs a category such as "Category 1" with a space. Spaces are obviously not desirable as CSS classes so if we could maybe just have a dash added to replace the space that would be perfect - just not sure how to accomplish that?


3 Answers 3


Just use $category->slug instead of $category->cat_name. Slugs are already lowercase and with dashes instead of spaces.


sanitize_html_class sanitizes a html classname to ensure it only contains valid characters.

foreach((get_the_category($post->ID)) as $category)
    $classes [] = sanitize_html_class($category->cat_name);

sanitize_title_with_dashes should do the trick.


foreach((get_the_category($post->ID)) as $category)
    $classes [] = sanitize_title_with_dashes($category->cat_name);
  • Thanks for the response! All i see for working examples on their reference page however is to use a specific title, mine is dynamic depending on the category so Im not too sure how to add this to my function unfortunately.
    – Mr.Brown
    Jan 13, 2013 at 1:24
  • @Mr.Brown: I added an example.
    – akTed
    Jan 13, 2013 at 1:48
  • Really appreciate the help AKTed, I +1'd your response since you went out of the way to show me a working example...I decided to go with pogoking answer since though since his answer was a much cleaner solution. Both are viable options though so thank you!
    – Mr.Brown
    Jan 13, 2013 at 3:37

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