Delist entries in the_loop

Question

I am trying to add a delisting feature to my WordPress network. Posts which are delisted would not appear in post lists, but would still be visible if accessed directly.

I've written a plugin that helps editors delist entries with custom meta values on authors and posts. So there are two meta values that I need to check before displaying each post in public listings: the delist-post post meta value and the delist-author user meta value.

I was hoping to register a pre_get_posts filter that limits the return of get_posts() by setting the query's meta_query property. Is it possible to check a user meta value with a posts meta_query? If not, can you think of a better way to do this without adding conditional statements in theme files (i.e. not if (!get_post_meta(...) && !get_user_meta(...)) in the_loop)?

Answer 1

If you're using WP_Query to do your loop it should be as simple as getting all the post IDs and then setting them as negative in the p parameter.

For example:

$unwanted_posts = array(); // you must generate this
$unwanted_posts_str = '-'.implode( ',-', $unwanted_posts );

$args = array(
    'p' => $unwanted_posts_str
);

You can also set this on an existing query using the set() method.

Answer 2

Shortly after writing my question, The Theme Foundry wrote a blog entry that answered my question. The solution is to add_actions for both posts_join and posts_where. These each take clauses as arguments, which you append with your own conditions and return the appended clause.

In my case, I just had to limit the join in the posts_join callback:

$join .= " 
            LEFT JOIN    " . $wpdb->postmeta . " AS pm 
            ON           (" . $wpdb->posts . ".ID = pm.post_id AND 
                        pm.meta_key = 'post_meta_key_here') 
            LEFT JOIN    " . $wpdb->usermeta . " AS um 
            ON           (" . $wpdb->posts . ".post_author = um.user_id AND 
                        um.meta_key = 'author_meta_key_here') "

... and the where clause in the posts_where callback...

$where .= " 
                AND ((pm.meta_key = 'post_meta_key_here' AND pm.meta_value = 0)
                    OR pm.meta_id IS NULL) 
                AND ((um.meta_key = 'author_meta_key_here' AND um.meta_value = 0)
                    OR um.umeta_id IS NULL) ";

Please see the blog post for more information.

Answer 3

I would use pre_get_posts:

<?php
function wpse52961_filter_delisted_posts( $query ) {
    // Only modify the main query
    // NOTE: You'll need to change this if
    // you intend to target a specific secondary query
    if ( $query->is_main_query() ) {
        // Define meta query
        $filtered_posts_meta_query = array(
            'relation' => 'OR',
            array(
                'meta_key' => 'delist-post',
                'meta_value' => true
            ),
            array(
                'meta_key' => 'delist-author',
                'meta_value' => true
            )

        );
        // Add the meta query args to the query
        $query->set( 'meta_query', $filtered_posts_meta_query );
    }
}
add_action( 'pre_get_posts', 'wpse52961_filter_delisted_posts' );
?>

I've made some assumptions about the meta key values, and the desired relationship between delist-post and delist-author.