Add code to a specific post's content

Question

I want to add a button on top of all posts have catogery "music", Here's what I have tried but it does not work at all. Please give me advice.

  function add_go_back_btn($content) {
       global $post;
       $cat = get_the_category();
       $post_type = get_post_type();
       if($cat === 'music' && $post_type === 'post') {
            return '<div><a href="/music">This is a button</a></div>' . $content;
       }
       else return $content;
   }

   add_filter( 'the_content', 'add_go_back_btn' );

Answer 1

Your code is fine, but your logic isn't working because of $cat. $cat is returning an Array with an Object which you're trying to check against. But you can easily just use in_category('music') like this:

function add_go_back_btn($content) {
 global $post;
 $cat = get_the_category();
 $post_type = get_post_type();

 if(in_category('music') && $post_type === 'post') {
    return '<div><a href="/music">This is a button</a></div>' . $content;
 } else return $content;
}
add_filter( 'the_content', 'add_go_back_btn' );