example-field-setup.php

<?php
/*
 * Example setup for the custom Attached Posts field for CMB2.
 */

/**
 * Get the bootstrap! If using as a plugin, REMOVE THIS!
 */
require_once WPMU_PLUGIN_DIR . '/cmb2/init.php';
require_once WPMU_PLUGIN_DIR . '/cmb2-attached-posts/cmb2-attached-posts-field.php';

/**
 * Define the metabox and field configurations.
 *
 * @param  array $meta_boxes
 * @return array
 */
function cmb2_attached_posts_field_metaboxes_example() {

    $example_meta = new_cmb2_box( array(
        'id'           => 'cmb2_attached_posts_field',
        'title'        => __( 'Attached Posts', 'yourtextdomain' ),
        'object_types' => array( 'page' ), // Post type
        'context'      => 'normal',
        'priority'     => 'high',
        'show_names'   => false, // Show field names on the left
    ) );

    /**
     * Example with no limit
     */
    $example_meta->add_field( array(
        'name'    => __( 'Attached Posts', 'yourtextdomain' ),
        'desc'    => __( 'Drag posts from the left column to the right column to attach them to this page.<br />You may rearrange the order of the posts in the right column by dragging and dropping.', 'yourtextdomain' ),
        'id'      => 'attached_cmb2_attached_posts',
        'type'    => 'custom_attached_posts',
        'column'  => true, // Output in the admin post-listing as a custom column. https://github.com/CMB2/CMB2/wiki/Field-Parameters#column
        'options' => array(
            'show_thumbnails' => true, // Show thumbnails on the left
            'filter_boxes'    => true, // Show a text box for filtering the results
            'query_args'      => array(
                'posts_per_page' => 10,
                'post_type'      => 'page',
            ), // override the get_posts args
        ),
    ) );

    /**
     * Example with limit
     */
    $example_meta->add_field( array(
        'name'    => __( 'Attached Users', 'yourtextdomain' ),
        'desc'    => __( 'Drag users from the left column to the right column to attach them to this page.<br />You may rearrange the order of the users in the right column by dragging and dropping.', 'yourtextdomain' ),
        'id'      => 'attached_cmb2_attached_users',
        'type'    => 'custom_attached_posts',
        'column'  => true, // Output in the admin post-listing as a custom column. https://github.com/CMB2/CMB2/wiki/Field-Parameters#column
        'options' => array(
            'show_thumbnails' => true, // Show thumbnails on the left
            'filter_boxes'    => true, // Show a text box for filtering the results
            'query_users'     => true, // Do users instead of posts/custom-post-types.
        ),
        'attributes' => array(
            'data-max-items' => 3, // Sets the max posts that can be attached to 3
        ),
    ) );

}
add_action( 'cmb2_init', 'cmb2_attached_posts_field_metaboxes_example' );