Function only on a specific page

Question

I am trying to run a function only on one page or other pages in the future if I so desire. But I dont want to run it site wide. I need help on how to put the if is_page or if is_single.

// disable auto-formatting
function my_formatter($content) {
    $new_content = '';
    $pattern_full = '{(\[raw\].*?\[/raw\])}is';
    $pattern_contents = '{\[raw\](.*?)\[/raw\]}is';
    $pieces = preg_split($pattern_full, $content, -1, PREG_SPLIT_DELIM_CAPTURE);

    foreach ($pieces as $piece) {
        if (preg_match($pattern_contents, $piece, $matches)) {
            $new_content .= $matches[1];
        } else {
            $new_content .= wptexturize(wpautop($piece));
        }
    }
    return $new_content;
}
remove_filter('the_content', 'wpautop');
remove_filter('the_content', 'wptexturize');
add_filter('the_content', 'my_formatter', 99);

Much appreciate the help.

Thanks

Answer 1

define the function:

// my_formatter - register custom text formatter for specified post or page
function my_formatter($content) {
    $new_content = '';
    $pattern_full = '{(\[raw\].*?\[/raw\])}is';
    $pattern_contents = '{\[raw\](.*?)\[/raw\]}is';
    $pieces = preg_split($pattern_full, $content, -1, PREG_SPLIT_DELIM_CAPTURE);

    foreach ($pieces as $piece) {
        if (preg_match($pattern_contents, $piece, $matches)) {
            $new_content .= $matches[1];
        } else {
            $new_content .= wptexturize(wpautop($piece));
        }
    }
    return $new_content;
}

Simply add the following code. you should change 100 with your desired page ID.

if ( is_page( 100 ) ){ // you should change this line
    remove_filter('the_content', 'wpautop');
    remove_filter('the_content', 'wptexturize');
    add_filter('the_content', 'my_formatter', 99);
}

Answer 2

You may have already solved this, but here's one example how to conditionally add filter to single page or post.

// Check, if custom formatter needs to be added
add_action(
    'template_redirect',
    function() {
        // don't do anything, if not page or post
        if ( ! is_singular( array('page', 'post') ) ) {
            // some other type
            return;
        }

        // targetted page or post
        // add other post or page slugs or ID to array
        // to use custom formatter on them
        $targets = array(
            'some-post-name', // names/slugs
            12, // or IDs
        );

        // check, that current post/page is one of the targets
        global $post;
        $current = array($post->ID, $post->post_name);
        if ( ! array_intersect( $current, $targets ) ) {
            // current ID or slug was not in the targets array
            return;
        }

        // We're on a targeted post or page, so let's do stuff!

        // remove default formatters
        remove_filter('the_content', 'wpautop');
        remove_filter('the_content', 'wptexturize');

        // add custom formatter
        add_filter('the_content', 'my_formatter', 99);
    }
);

function my_formatter($content) {
    // code...
}