An ACF Relationship field with multisite support. Tested with ACF 6.3.6

acf-relationship-multisite.php

<?php

/**
 * An ACF Relationship field with multisite support. Tested with ACF 6.3.6 
 * 
 * This aims to be the lightest possible implementation of a multisite compatible relationship field.
 * For the php class we extend the existing ACF Relationship field and override the necessary methods.
 * 
 * For the JavaScript, we copy the existing ACF Relationship field and modify only the necessary properties.
 * 
 * There are minor CSS changes to the field type.
 * 
 * This code should be added to your theme's functions.php file.
 * 
 * add_action( 'acf/include_field_types', 'include_acf_relationship_multisite' );
 * function include_acf_relationship_multisite() {
 *   include_once('acf-relationship-multisite.php');
 * }
 * 
 * TODO
 * - Taxonomy filter only works for the current subsite. These should update as the blog_id filter changes.
 * - Comment where parts of php and js functions are different to the original relationship field.
 * - Document the returned field values.
 */

if (! class_exists('acf_field_relationship_multisite')) :

	class acf_field_relationship_multisite extends acf_field_relationship
	{


		/**
		 * This function will setup the field type data
		 *
		 * @type    function
		 * @date    5/03/2014
		 * @since   5.0.0
		 */
		public function initialize()
		{
			$this->name          = 'relationship_multisite';
			$this->label         = __('Relationship (multisite)', 'acf');
			$this->category      = 'relational';
			$this->description   = __('A multisite compatible variation of the relationship field.', 'acf');
			$this->preview_image = acf_get_url() . '/assets/images/field-type-previews/field-preview-relationship.png';
			$this->doc_url       = null;
			$this->defaults      = array(
				'post_type'            => array(),
				'taxonomy'             => array(),
				'min'                  => 0,
				'max'                  => 0,
				'filters'              => array('search', 'post_type', 'taxonomy', 'blog_id'),
				'elements'             => array(),
				'return_format'        => 'object',
				'bidirectional_target' => array(),
			);

			add_filter('acf/conditional_logic/choices', array($this, 'render_field_relation_conditional_choices'), 10, 3);

			// extra
			add_action('wp_ajax_acf/fields/relationship_multisite/query', array($this, 'ajax_query'));
			add_action('wp_ajax_nopriv_acf/fields/relationship_multisite/query', array($this, 'ajax_query'));
		}

		/**
		 * Returns a list of pretty subsites.
		 * 
		 * This function is similar to acf_get_pretty_post_types() and acf_get_pretty_taxonomies().
		 * 
		 * @param array $blog_ids
		 * @return array $r - an associative array of blog_id => blogname
		 */
		private function acf_get_pretty_subsites($blog_ids = array())
		{
			$blogs = get_sites();
			$r = array();
			foreach ($blogs as $blog) {
				if (!empty($blog_ids) && !in_array($blog->blog_id, $blog_ids)) {
					continue;
				}
				$r[$blog->blog_id] = $blog->blogname;
			}
			return $r;
		}

		/**
		 * Filters choices in relation conditions.
		 *
		 * @since 6.3
		 *
		 * @param array  $choices           The selected choice.
		 * @param array  $conditional_field The conditional field settings object.
		 * @param string $rule_value        The rule value.
		 * @return array
		 */
		public function render_field_relation_conditional_choices($choices, $conditional_field, $rule_value)
		{
			if (! is_array($conditional_field) || $conditional_field['type'] !== 'relationship_multisite') {
				return $choices;
			}
			if (! empty($rule_value)) {
				$post_title = get_the_title($rule_value);
				$choices    = array($rule_value => $post_title);
			}
			return $choices;
		}


		/**
		 * This function will return an array of data formatted for use in a select2 AJAX response
		 *
		 * @since   5.0.9
		 *
		 * @param array $options An array of options for the query.
		 * @return array
		 */
		public function get_ajax_query($options = array())
		{
			// defaults
			$options = wp_parse_args(
				$options,
				array(
					'post_id'   => 0,
					's'         => '',
					'field_key' => '',
					'paged'     => 1,
					'post_type' => '',
					'include'   => '',
					'taxonomy'  => '',
					'blog_id'   => '',
				)
			);

			// load field
			$field = acf_get_field($options['field_key']);
			if (! $field) {
				return false;
			}

			// vars
			$results   = array();
			$args      = array();
			$s         = false;
			$is_search = false;

			// paged
			$args['posts_per_page'] = 20;
			$args['paged']          = intval($options['paged']);

			// search
			if ($options['s'] !== '' && empty($options['include'])) {
				// strip slashes (search may be integer)
				$s = wp_unslash(strval($options['s']));

				// update vars
				$args['s'] = $s;
				$is_search = true;
			}

			// post_type
			if (! empty($options['post_type'])) {
				$args['post_type'] = acf_get_array($options['post_type']);
			} elseif (! empty($field['post_type'])) {
				$args['post_type'] = acf_get_array($field['post_type']);
			} else {
				$args['post_type'] = acf_get_post_types();
			}

			// post status
			if (! empty($options['post_status'])) {
				$args['post_status'] = acf_get_array($options['post_status']);
			} elseif (! empty($field['post_status'])) {
				$args['post_status'] = acf_get_array($field['post_status']);
			}

			// blog id
			if (! empty($options['blog_id'])) {
				// Add the blog_id to the args array - so that it can be filtered.
				$args['blog_id'] = $options['blog_id'];
			} elseif (! empty($field['blog_id'])) {
				$args['blog_id'] = $field['blog_id'];
			}

			// taxonomy
			if (! empty($options['taxonomy'])) {

				// vars
				$term = acf_decode_taxonomy_term($options['taxonomy']);

				// tax query
				$args['tax_query'] = array();

				// append
				$args['tax_query'][] = array(
					'taxonomy' => $term['taxonomy'],
					'field'    => 'slug',
					'terms'    => $term['term'],
				);
			} elseif (! empty($field['taxonomy'])) {

				// vars
				$terms = acf_decode_taxonomy_terms($field['taxonomy']);

				// append to $args
				$args['tax_query'] = array(
					'relation' => 'OR',
				);

				// now create the tax queries
				foreach ($terms as $k => $v) {
					$args['tax_query'][] = array(
						'taxonomy' => $k,
						'field'    => 'slug',
						'terms'    => $v,
					);
				}
			}

			if (! empty($options['include'])) {
				// If we have an include, we need to return only the selected posts.
				$args['post__in'] = array($options['include']);
			}

			// filters
			$args = apply_filters('acf/fields/relationship_multisite/query', $args, $field, $options['post_id']);
			$args = apply_filters('acf/fields/relationship_multisite/query/name=' . $field['name'], $args, $field, $options['post_id']);
			$args = apply_filters('acf/fields/relationship_multisite/query/key=' . $field['key'], $args, $field, $options['post_id']);

			// Get the blog id from the args array.
			$blog_id = $args['blog_id'] && (int) $args['blog_id'] > 0 ? (int) $args['blog_id'] : 0;
			// Remove the blog_id from the args array - so that it doesn't interfere with the query.
			unset($args['blog_id']);

			// If blog id is set, switch to that blog
			$blog_id && switch_to_blog($blog_id);

			// get posts grouped by post type
			$groups = acf_get_grouped_posts($args);

			// bail early if no posts
			if (empty($groups)) {
				// Restore the current blog, since we switched earlier.
				$blog_id &&	restore_current_blog();

				return false;
			}

			// loop
			foreach (array_keys($groups) as $group_title) {

				// vars
				$posts = acf_extract_var($groups, $group_title);

				// data
				$data = array(
					'text'     => $group_title,
					'children' => array(),
				);



				// convert post objects to post titles
				foreach (array_keys($posts) as $post_id) {

					$posts[$post_id] = $this->get_post_title($posts[$post_id], $field, $options['post_id']);
				}

				// order posts by search
				if ($is_search && empty($args['orderby']) && isset($args['s'])) {
					$posts = acf_order_by_search($posts, $args['s']);
				}

				// append to $data
				foreach (array_keys($posts) as $post_id) {
					$compound_id = $blog_id ? $post_id . ',' . $blog_id : $post_id;
					$data['children'][] = $this->get_post_result($compound_id, $posts[$post_id]);
				}

				// append to $results
				$results[] = $data;
			}

			// Restore the current blog, since we switched earlier.
			$blog_id &&	restore_current_blog();

			// add as optgroup or results
			if (count($args['post_type']) == 1) {
				$results = $results[0]['children'];
			}

			// vars
			$response = array(
				'results' => $results,
				'limit'   => $args['posts_per_page'],
			);

			// return
			return $response;
		}

		private function postAndBlogToId($post_id, $blog_id)
		{
			return $blog_id ? $post_id . ',' . $blog_id : $post_id;
		}

		private function idToPostAndBlog($id)
		{
			$parts = explode(',', $id);
			return array(
				'post_id' => $parts[0],
				'blog_id' => count($parts) > 1 ? $parts[1] : 0
			);
		}


		/**
		 * This function returns the HTML for a result
		 *
		 * @type    function
		 * @date    1/11/2013
		 * @since   5.0.0
		 *
		 * @param   $post (object)
		 * @param   $field (array)
		 * @param   $post_id (int) the post_id to which this value is saved to
		 * @return  (string)
		 */
		function get_post_title($post, $field, $post_id = 0, $is_search = 0)
		{

			// get post_id
			if (! $post_id) {
				$post_id = acf_get_form_data('post_id');
			}

			// vars
			$title = acf_get_post_title($post, $is_search);

			// featured_image
			if (acf_in_array('featured_image', $field['elements'])) {

				// vars
				$class     = 'thumbnail';
				$thumbnail = acf_get_post_thumbnail($post->ID, array(17, 17));

				// icon
				if ($thumbnail['type'] == 'icon') {
					$class .= ' -' . $thumbnail['type'];
				}

				// append
				$title = '<div class="' . $class . '">' . $thumbnail['html'] . '</div>' . $title;
			}

			// filters
			$title = apply_filters('acf/fields/relationship_multisite/result', $title, $post, $field, $post_id);
			$title = apply_filters('acf/fields/relationship_multisite/result/name=' . $field['_name'], $title, $post, $field, $post_id);
			$title = apply_filters('acf/fields/relationship_multisite/result/key=' . $field['key'], $title, $post, $field, $post_id);

			// return
			return $title;
		}


		/**
		 * Create the HTML interface for your field
		 *
		 * @param   $field - an array holding all the field's data
		 *
		 * @type    action
		 * @since   3.6
		 * @date    23/01/13
		 */
		function render_field($field)
		{

			// vars
			$post_type = acf_get_array($field['post_type']);
			$taxonomy  = acf_get_array($field['taxonomy']);
			$blog_id   = acf_get_array($field['blog_id']);
			$filters   = acf_get_array($field['filters']);

			// filters
			$filter_count             = count($filters);
			$filter_post_type_choices = array();
			$filter_taxonomy_choices  = array();
			$filter_blog_id_choices   = array();


			// post_type filter
			if (in_array('post_type', $filters)) {
				$filter_post_type_choices = array(
					'' => __('Select post type', 'acf'),
				) + acf_get_pretty_post_types($post_type);
			}


			// blog_id filter
			if (in_array('blog_id', $filters)) {
				// Get all blogs
				$pretty_blogs = $this->acf_get_pretty_subsites($blog_id);

				// Get this blog id
				$current_blog_id = get_current_blog_id();

				// Initialize the choices array
				$filter_blog_id_choices = array();

				// If the current blog is in the list
				if (isset($pretty_blogs[$current_blog_id])) {
					// Add the current blog to the top of the list
					$filter_blog_id_choices[$current_blog_id] = $pretty_blogs[$current_blog_id];

					// Remove the current blog from the list
					unset($pretty_blogs[$current_blog_id]);
				}

				// Add the rest of the blogs to the list
				$filter_blog_id_choices = $filter_blog_id_choices + $pretty_blogs;
			}

			// taxonomy filter
			if (in_array('taxonomy', $filters)) {
				$term_choices            = array();
				$filter_taxonomy_choices = array(
					'' => __('Select taxonomy', 'acf'),
				);

				// check for specific taxonomy setting
				if ($taxonomy) {
					$terms        = acf_get_encoded_terms($taxonomy);
					$term_choices = acf_get_choices_from_terms($terms, 'slug');

					// if no terms were specified, find all terms
				} else {

					// restrict taxonomies by the post_type selected
					$term_args = array();
					if ($post_type) {
						$term_args['taxonomy'] = acf_get_taxonomies(
							array(
								'post_type' => $post_type,
							)
						);
					}

					// get terms
					$terms        = acf_get_grouped_terms($term_args);
					$term_choices = acf_get_choices_from_grouped_terms($terms, 'slug');
				}

				// append term choices
				$filter_taxonomy_choices = $filter_taxonomy_choices + $term_choices;
			}

			// div attributes
			$atts = array(
				'id'             => $field['id'],
				// Keep the acf-relationship class for styling compatibility
				// Add the acf-relationship-multisite class for custom styling nd js targeting
				'class'          => "acf-relationship acf-relationship-multisite {$field['class']}",
				'data-min'       => $field['min'],
				'data-max'       => $field['max'],
				'data-s'         => '',
				'data-paged'     => 1,
				'data-post_type' => '',
				'data-taxonomy'  => '',
				'data-blog_id'   => '',
				'data-nonce'     => wp_create_nonce($field['key']),
			);

?>
			<div <?php echo acf_esc_attrs($atts); ?>>

				<?php
				acf_hidden_input(
					array(
						'name'  => $field['name'],
						'value' => '',
					)
				);
				?>

				<?php

				/* filters */
				if ($filter_count) :
				?>
					<div class="filters -f<?php echo esc_attr($filter_count); ?>">
						<?php

						/* search */
						if (in_array('search', $filters)) :
						?>
							<div class="filter -search">
								<?php
								acf_text_input(
									array(
										'placeholder' => __('Search...', 'acf'),
										'data-filter' => 's',
									)
								);
								?>
							</div>
						<?php
						endif;

						/* blog_id */
						if (in_array('blog_id', $filters)) :
						?>
							<div class="filter -blog_id">
								<?php
								acf_select_input(
									array(
										'choices'     => $filter_blog_id_choices,
										'data-filter' => 'blog_id',
										'value'       => array_keys($filter_blog_id_choices)[0]
									)
								);
								?>
							</div>
						<?php
						endif;

						/* post_type */
						if (in_array('post_type', $filters)) :
						?>
							<div class="filter -post_type">
								<?php
								acf_select_input(
									array(
										'choices'     => $filter_post_type_choices,
										'data-filter' => 'post_type',
									)
								);
								?>
							</div>
						<?php
						endif;

						/* post_type */
						if (in_array('taxonomy', $filters)) :
						?>
							<div class="filter -taxonomy">
								<?php
								acf_select_input(
									array(
										'choices'     => $filter_taxonomy_choices,
										'data-filter' => 'taxonomy',
									)
								);
								?>
							</div>
						<?php endif; ?>
					</div>
				<?php endif; ?>

				<div class="selection">
					<div class="choices">
						<ul class="acf-bl list choices-list"></ul>
					</div>
					<div class="values">
						<ul class="acf-bl list values-list">
							<?php
							if (! empty($field['value'])) :

								// loop
								foreach ($field['value'] as $compound_id) :
									// Get the post_id and blog_id from the compound id
									$ids = $this->idToPostAndBlog($compound_id);
									$post_title_suffix = '';

									// Is blog_id current blog? Then set it to 0
									if (absint($ids['blog_id']) === get_current_blog_id()) {
										$ids['blog_id'] = 0;
									}

									if ($ids['blog_id']) {
										switch_to_blog($ids['blog_id']);
										$post_title_suffix = ' (' . get_bloginfo('name') . ')';
									}

									// get post
									$post = get_post($ids['post_id']);

									// validate
									if (! $post) {
										error_log('no post');
										if ($ids['blog_id']) {
											restore_current_blog();
										}
										continue;
									}

							?>
									<li>
										<?php
										acf_hidden_input(
											array(
												'name'  => $field['name'] . '[]',
												'value' => $compound_id,
											)
										);
										?>
										<span tabindex="0" data-id="<?php echo $compound_id; ?>" class="acf-rel-item acf-rel-item-remove">
											<?php echo acf_esc_html($this->get_post_title($post, $field)) . $post_title_suffix; ?>
											<a href="#" class="acf-icon -minus small dark" data-name="remove_item"></a>
										</span>
									</li>
									<?php
									if ($ids['blog_id']) {
										restore_current_blog();
									}
									?>
								<?php endforeach; ?>
							<?php endif; ?>
						</ul>
					</div>
				</div>
			</div>
<?php
		}


		/**
		 * Create extra options for your field. This is rendered when editing a field.
		 * The value of $field['name'] can be used (like bellow) to save extra data to the $field
		 *
		 * @type    action
		 * @since   3.6
		 * @date    23/01/13
		 *
		 * @param   $field  - an array holding all the field's data
		 */
		function render_field_settings($field)
		{
			acf_render_field_setting(
				$field,
				array(
					'label'        => __('Filter by Post Type', 'acf'),
					'instructions' => '',
					'type'         => 'select',
					'name'         => 'post_type',
					'choices'      => acf_get_pretty_post_types(),
					'multiple'     => 1,
					'ui'           => 1,
					'allow_null'   => 1,
					'placeholder'  => __('All post types', 'acf'),
				)
			);

			acf_render_field_setting(
				$field,
				array(
					'label'        => __('Filter by Post Status', 'acf'),
					'instructions' => '',
					'type'         => 'select',
					'name'         => 'post_status',
					'choices'      => acf_get_pretty_post_statuses(),
					'multiple'     => 1,
					'ui'           => 1,
					'allow_null'   => 1,
					'placeholder'  => __('Any post status', 'acf'),
				)
			);

			acf_render_field_setting(
				$field,
				array(
					'label'        => __('Filter by Taxonomy', 'acf'),
					'instructions' => '',
					'type'         => 'select',
					'name'         => 'taxonomy',
					'choices'      => acf_get_taxonomy_terms(),
					'multiple'     => 1,
					'ui'           => 1,
					'allow_null'   => 1,
					'placeholder'  => __('All taxonomies', 'acf'),
				)
			);

			acf_render_field_setting(
				$field,
				array(
					'label'        => __('Filter by Subsite', 'acf'),
					'instructions' => '',
					'type'         => 'select',
					'name'         => 'blog_id',
					'choices'      => $this->acf_get_pretty_subsites(),
					'multiple'     => 1,
					'ui'           => 1,
					'allow_null'   => 1,
					'placeholder'  => __('All subsites', 'acf'),
				)
			);

			acf_render_field_setting(
				$field,
				array(
					'label'        => __('Filters', 'acf'),
					'instructions' => '',
					'type'         => 'checkbox',
					'name'         => 'filters',
					'choices'      => array(
						'search'    => __('Search', 'acf'),
						'post_type' => __('Post Type', 'acf'),
						'taxonomy'  => __('Taxonomy', 'acf'),
						'blog_id'  => __('Subsite', 'acf'),
					),
				)
			);

			acf_render_field_setting(
				$field,
				array(
					'label'        => __('Return Format', 'acf'),
					'instructions' => '',
					'type'         => 'radio',
					'name'         => 'return_format',
					'choices'      => array(
						'object' => __('Post Object', 'acf'),
						'id'     => __('Post ID and Blog ID', 'acf'),
					),
					'layout'       => 'horizontal',
				)
			);
		}


		/**
		 * This filter is applied to the $value after it is loaded from the db and before it is returned to the template
		 *
		 * @type    filter
		 * @since   3.6
		 * @date    23/01/13
		 *
		 * @param   $value (mixed) the value which was loaded from the database
		 * @param   $post_id (mixed) the post_id from which the value was loaded
		 * @param   $field (array) the field array holding all the field options
		 *
		 * @return  $value (mixed) the modified value
		 */
		function format_value($value, $post_id, $field)
		{
			// bail early if no value
			if (empty($value)) {
				return $value;
			}

			// force value to array
			$value = acf_get_array($value);

			$value = array_map(function ($v) {
				$ids = $this->idToPostAndBlog($v);
				$ids['post_id'] = intval($ids['post_id']);
				$ids['blog_id'] = intval($ids['blog_id']);
				return $ids;
			}, $value);

			// load posts if needed
			if ($field['return_format'] == 'object') {

				// get posts
				$value =  array_map(function ($v) use ($field) {
					if($v['blog_id'] === 0) {
						return get_post($v['post_id']);
					}
					switch_to_blog($v['blog_id']);
					$post = get_post($v['post_id']);
					// Check the post type
					if (!empty($field['post_type']) && !in_array($post->post_type, $field['post_type'])) {
						$post = null;
					}
					restore_current_blog();
					if($post) {
						$post->blog_id = $v['blog_id'];
					}
					return $post;
				}, $value);
			}

			// return
			return $value;
		}


		/**
		 * Filters the field value before it is saved into the database.
		 *
		 * @since 3.6
		 *
		 * @param mixed   $value   The value which will be saved in the database.
		 * @param integer $post_id The post_id of which the value will be saved.
		 * @param array   $field   The field array holding all the field options.
		 *
		 * @return mixed $value The modified value.
		 */
		public function update_value($value, $post_id, $field)
		{
			// Bail early if no value.
			if (empty($value)) {
				acf_update_bidirectional_values(array(), $post_id, $field);
				return $value;
			}

			// Format array of values.
			// - ensure each value is an id, or in the pattern blog_id:id.
			// - Parse each id as string for SQL LIKE queries.
			if (acf_is_sequential_array($value)) {

				$value = array_map(function ($v) {
					$ids = $this->idToPostAndBlog($v);
					$ids['post_id'] = acf_idval($ids['post_id']);
					$ids['post_id'] = strval($ids['post_id']);
					return $this->postAndBlogToId($ids['post_id'], $ids['blog_id']);
				}, $value);

				// Parse single value for id.
			} else {
				$ids = $this->idToPostAndBlog($value);
				$ids['post_id'] = acf_idval($ids['post_id']);
			}

			acf_update_bidirectional_values(acf_get_array($value), $post_id, $field);

			// Return value.
			return $value;
		}

		/**
		 * Return the schema array for the REST API.
		 *
		 * @param array $field
		 * @return array
		 */
		public function get_rest_schema(array $field)
		{
			$schema = array(
				'type'     => array('string', 'array', 'null'),
				'required' => ! empty($field['required']),
				'items'    => array(
					'type' => 'string',
				),
			);

			if (empty($field['allow_null'])) {
				$schema['minItems'] = 1;
			}

			if (! empty($field['min'])) {
				$schema['minItems'] = (int) $field['min'];
			}

			if (! empty($field['max'])) {
				$schema['maxItems'] = (int) $field['max'];
			}

			return $schema;
		}
	}

	// initialize
	acf_register_field_type('acf_field_relationship_multisite');

endif; // class_exists check


/**
 * JavaScript to register the field type
 *
 * Copy the way that ACF registers its field types in it's js file:
 * advanced-custom-fields-pro/assets/build/js/acf-input.js
 * 
 * But, instead of writing the field group from scratch, 
 * we can copy the existing relationship field and modify it.
 */
$acf_relationship_multisite_script = <<<JS
(function($, undefined) {
	var FieldCopy = acf.models["RelationshipField"].prototype;

	var RelationshipMultisiteField = acf.Field.extend({
		type: "relationship_multisite",
		events: FieldCopy.events,		
		\$control: function () {
			return this.$('.acf-relationship-multisite');
		},
		\$list: FieldCopy.\$list,
		\$listItems: FieldCopy.\$listItems,
		\$listItem: FieldCopy.\$listItem,
		getValue: FieldCopy.getValue,
		newChoice: FieldCopy.newChoice,
		newValue: FieldCopy.newValue,
		initialize: function () {
			// Get the initial filter value for blog_id
			var \$el = this.\$('.filter.-blog_id select');
			var val = \$el.val();
			var filter = \$el.data('filter');
			// update attr
			this.set(filter, val);

			// Run the original initialize function
			FieldCopy.initialize.call(this);
		},
		onScrollChoices: FieldCopy.onScrollChoices,
		onKeypressFilter: FieldCopy.onKeypressFilter,
		onChangeFilter: FieldCopy.onChangeFilter,
		onClickAdd: FieldCopy.onClickAdd,
		onClickRemove: FieldCopy.onClickRemove,
		onTouchStartValues: FieldCopy.onTouchStartValues,
		maybeFetch: FieldCopy.maybeFetch,
		getAjaxData: function () {
			// load data based on element attributes
			var ajaxData = this.\$control().data();
			for (var name in ajaxData) {
				ajaxData[name] = this.get(name);
			}

			// extra
			ajaxData.action = 'acf/fields/relationship_multisite/query';
			ajaxData.field_key = this.get('key');
			ajaxData.nonce = this.get('nonce');

			// Filter.
			ajaxData = acf.applyFilters('relationship_multisite_ajax_data', ajaxData, this);

			// return
			return ajaxData;
		},
		fetch: FieldCopy.fetch,
		walkChoices: FieldCopy.walkChoices,
	});

	acf.registerFieldType(RelationshipMultisiteField);
})(jQuery);
JS;

/**
 * Add inline script to the footer
 */
add_action(
	'acf/input/admin_print_footer_scripts',
	function () use ($acf_relationship_multisite_script) {
		echo "<script type='text/javascript'>{$acf_relationship_multisite_script}</script>";
	}
);


/**
 * CSS related to the field type
 *
 * 1. Centre the field type label - this element is shown in the modal when 'Browse Fields' is clicked.
 * 2. If there are 4 filters on the field, make the filter width 25%.
 */
$acf_relationship_multisite_styles = <<<CSS
.acf-field-type[data-field-type="relationship_multisite"] .field-type-label {
	text-align: center;
}
.acf-relationship-multisite .filters.-f4 .filter {
  width: 25%;
}
CSS;

/**
 * Add inline styles to the header
 */
add_action(
	'acf/input/admin_print_scripts',
	function () use ($acf_relationship_multisite_styles) {
		echo "<style type='text/css'>{$acf_relationship_multisite_styles}</style>";
	}
);