Exclude page from loop results

Question

I am having difficulties excluding a specific page from my main index loop in my child theme.

I have the following function found in functions.php that modifies my index.php loop so that it displays pages instead of posts:

add_action( 'pre_get_posts', 'pages_loop_on_index' );
function pages_loop_on_index( $query ) {

if ( $query->is_home() && $query->is_main_query() ) {
    $query->set( 'post_type', array( 'page' ) );
    $query->set( 'posts_per_page', -1 );
}
}

So far, so good.

I want to make it so that the loop ignores page ID 34 but I can't get this part to work.

I've tried using :

$query->set( 'category__not_in', '34' );

Still shows up.

I've tried :

$query->set( 'exclude', '34' );

But the page still shows up.

What am I doing wrong?

Here's the code for index.php:

<div id="primary" class="content-area">
    <main id="main" class="site-main" role="main">

    <?php if ( have_posts() ) : ?>

        <?php /* Start the Loop */ ?>
        <?php while ( have_posts() ) : the_post(); ?>

            <?php
                /* Include the Post-Format-specific template for the content.
                 * If you want to override this in a child theme, then include a file
                 * called content-___.php (where ___ is the Post Format name) and that will be used instead.
                 */
                get_template_part( 'content', get_post_format() );
            ?>

        <?php endwhile; ?>

        <?php boardwalk_paging_nav(); ?>

    <?php else : ?>

        <?php get_template_part( 'content', 'none' ); ?>

    <?php endif; ?>

    </main><!-- #main -->
</div>

Answer 1

You need the WP_Query documentation. WP_Query is very powerful, and you can do a lot with it :)

In your case, I don't think exclude is a valid parameter. What you're probably looking for is this:

$query->set( 'post__not_in', array( 34 ) );

Here's the Post & Page Parameters section of the documentation, which covers this and the other parameters you can use.

(Incidentally, the other one you tried, category__not_in, will only exclude posts from category ID 34, not posts/pages with the specific ID 34)

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By the way, you should also add an !is_admin() check to your function, otherwise you might find that this page starts to get excluded from display in the admin area as well.