Create columns

The Column class allows developers to create reusable, self-contained columns for the post listing table in the WordPress admin. These custom columns can display post meta, taxonomy values, or any custom data related to the post or taxonomy.

Columns are defined by extending the abstract PostTypes\Column class and implementing the required name() method, along with any optional logic such as rendering, sorting, or changing the label.

Creating a Custom Column

To create a custom column, extend the base Column class and implement the methods you need. Here's an example of a PriceColumn that pulls a _price meta field from the post and displays it in the admin list table:

use PostTypes\Column;

class PriceColumn extends Column
{
    /**
     * Defines the column key used internally.
     *
     * @return string.
     */
    public function name(): string
    {
        return 'price';
    }

    /**
     * Define the column label.
     *
     * @return string
     */
    public function label(): string
    {
        return __( 'Price', 'my-text-domain' );
    }

    /**
     * Position a column before/after another.
     *
     * @return array
     */
    public function position(): array
    {
        return $this->after( 'title' );
    }

    /**
     * Populate column callback.
     *
     * @return callable
     */
    public function populate(): callable
    {
        return function( int $post_id ) {
            echo '$' . get_post_meta( $post_id, '_price', true );
        };
    }

    /**
     * Handle sorting the column by modifying the admin query.
     *
     * @return callable
     */
    public function sort(): callable
    {
        return function( \WP_Query $query ) {
            $query->set( 'meta_key', '_price' );
            $query->set( 'orderby', 'meta_value_num' );
        };
    }
}

Adding the Column to a Post Type

Once you’ve defined your custom column, you can add it to a PostType using the $columns->column() method inside your PostType or Taxonomy class:

use PostTypes\PostType;

class Book extends PostType
{
    //...

    public function columns( Columns $columns ): Columns
    {
        $columns->column( new PriceColumn );

        return $columns;
    }
}