WordPress：pre_get_posts并将参数从author.php传递到function.php

Question

I'm trying to get pre_get_posts to work with passing arguments. I have the following function in my function.php file of my theme.

function cpt_on_author_page( $query, $user_id ) {   
    if ( $query->is_author() && $query->is_main_query() ) {
        $query->set( 'post_type', 'programs' );
        $query->set( 'posts_per_page', 1 );
        $query->set( 'meta_key' , 'show_program_editors');
        $query->set( 'meta_value' , $user_id);              
    }
}
add_action( 'pre_get_posts', 'cpt_on_author_page' );

I call this function via my author.php file via this code:

 do_action( 'pre_get_posts',$user_id );

On the output page, I am getting

 Missing argument 2 for cpt_on_author_page()

What am I doing wrong?

Answer 1

Try changing line 1 to function cpt_on_author_page( $query ) {

If you need to use $user_id (the ID of the current author) inside your function, you should be able to do something like this:

$author = get_user_by( 'slug', get_query_var( 'author_name' ) );
$user_id = $author->ID;

You shouldn't need do_action( 'pre_get_posts',$user_id ); at all.

Update (after discussion in this answer's comments):

To show all posts having a meta value of kam in kam 's author archive, you could do something like this:

function cpt_on_author_page( $query ) {

    if ( $query->is_author() ) {

        $users = get_users();
        $ids = array();
        foreach ( $users as $user ) {
            $ids[] = $user->ID;
        }
        $query->set( 'author__in' , $ids ); 

        $author = get_user_by( 'slug', get_query_var( 'author_name' ) );
        $query->set( 'meta_value' , $author->user_login );

    }
}
add_action( 'pre_get_posts', 'cpt_on_author_page' );

Notes: This assumes each author's nicename is the same as their username.