Adding custom columns to custom post types

Question

I've done this previously but I've forgotten the name of the hook, and can't find it anywhere...

What I'm trying to do is add some custom columns in the listing of a custom post type in the admin.

For example, in the admin, click on articles, I want to add custom column there.

Answer 1

The hooks to create custom columns and their associated data for a custom post type are manage_{$post_type}_posts_columns and manage_{$post_type}_posts_custom_column respectively, where {$post_type} is the name of the custom post type.

This example from the documentation removes the author column and adds a taxonomy and meta data column:

// Add the custom columns to the book post type:
add_filter( 'manage_book_posts_columns', 'set_custom_edit_book_columns' );
function set_custom_edit_book_columns($columns) {
    unset( $columns['author'] );
    $columns['book_author'] = __( 'Author', 'your_text_domain' );
    $columns['publisher'] = __( 'Publisher', 'your_text_domain' );

    return $columns;
}

// Add the data to the custom columns for the book post type:
add_action( 'manage_book_posts_custom_column' , 'custom_book_column', 10, 2 );
function custom_book_column( $column, $post_id ) {
    switch ( $column ) {

        case 'book_author' :
            $terms = get_the_term_list( $post_id , 'book_author' , '' , ',' , '' );
            if ( is_string( $terms ) )
                echo $terms;
            else
                _e( 'Unable to get author(s)', 'your_text_domain' );
            break;

        case 'publisher' :
            echo get_post_meta( $post_id , 'publisher' , true ); 
            break;

    }
}

Answer 2

I wrote a function that combines manage_{$post_type}_posts_columns filter and manage_{$post_type}_posts_custom_column action.

function add_admin_column($column_title, $post_type, $cb){

    // Column Header
    add_filter( 'manage_' . $post_type . '_posts_columns', function($columns) use ($column_title) {
        $columns[ sanitize_title($column_title) ] = $column_title;
        return $columns;
    } );

    // Column Content
    add_action( 'manage_' . $post_type . '_posts_custom_column' , function( $column, $post_id ) use ($column_title, $cb) {

        if(sanitize_title($column_title) === $column){
            $cb($post_id);
        }

    }, 10, 2 );
}

Usage:

add_admin_column(__('EAN'), 'product', function($post_id){
    echo get_post_meta( $post_id , 'ean' , true ); 
});

Answer 3

I'm not sure if it default custom meta data that you want to show as columns, but you could consider to use this free plugin that allows you to add columns to display custom fields. https://wordpress.org/plugins/codepress-admin-columns/

The pro version even allows you to add filtering, sorting and inline edit to those columns.

Answer 4

Based on Carlos response (thank you very much) I wanted to add a little thumbnail image, but not a featured one, one from custom metabox.

So this is what I added:

add_admin_column(__('Thumbnail'), 'obraz', function($post_id){
$image_id =  get_post_meta( $post_id , 'custom_thumbnail_metabox' , true );
echo '<img src="'.wp_get_attachment_image_url($image_id).'" />';

Info: the post meta will get the ID of the attachment/image so thats the reason for later call of wp_get_attachment_image_url