How should I be using filters and is_single together?

Question

I have a plugin that uses this filter to add some content to a Custom Post Type.

// From plugin:
add_filter( 'the_content', 'sixtenpresssermons_get_meta', 15 );

I'd like to remove that filter on certain views (singles).

I'd like to do so using code in my theme files - without editing the plugin.

I tried with the code below in functions.php, but obviously it's not working.

// Not working, in functions.php
if ( is_single('sermon') ) {
    remove_filter( 'the_content', 'sixtenpresssermons_get_meta', 15 )
}

Can I use conditionals with a filter like this, or how can I remove the filter on singles only?

Answer 1

You can do this in functions.php, but you have to make sure the function is hooked into wp. Any earlier than that and is_single is undefined.

Try adding this to functions.php:

/**
 * Unhooks sixtenpresssermons_get_meta from the_content if currently on single post.
 */
function sx_unhook_sixtenpresssermons_get_meta() {
    // Do nothing if this isn't single post
    if ( ! is_single() ) {
        return;
    }

    remove_filter( 'the_content', 'sixtenpresssermons_get_meta', 15 );
}
add_action( 'wp', 'sx_unhook_sixtenpresssermons_get_meta' );