Add REST API support to the Events Manager plugin for WordPress.

events-manager-rest-api.php

<?php
/**
 * Events Manager REST API
 * 
 * Add REST API support to the Events Manager plugin for WordPress.
 * 
 * https://wordpress.org/plugins/events-manager/
 */

namespace events_manager\rest_api;

/**
 * Register the event information in the REST API.
 */

add_action( 'init', __NAMESPACE__ . '\\init' );

function init() {
  $meta_fields = array(
    '_event_start',
    '_event_end',
    '_event_timezone',
  );
  foreach( (array) $meta_fields as $meta_field ) {
    register_meta( 'post', $meta_field, array(
      'object_subtype' => 'event',
      'type' => 'string',
      'description' => '',
      'single' => true,
      'sanitize_callback' => null,
      'auth_callback' => null,
      'show_in_rest' => true,
    ) );
  }
}

/**
 * Enable events in the REST API.
 */

add_filter( 'register_post_type_args', __NAMESPACE__ . '\\register_post_type_args', 10, 2 );

function register_post_type_args( $args, $post_type ) {
  if( 'event' === $post_type ) {
    $args['show_in_rest'] = true;
    $args['supports'][] = 'custom-fields';
  }
  return $args;
}

/**
 * Disable the Gutenberg editor for the custom post type.
 */

add_filter( 'use_block_editor_for_post_type', __NAMESPACE__ . '\\use_block_editor_for_post_type', 10, 2 );

function use_block_editor_for_post_type( $block_editor, $post_type ) {
  if( 'event' === $post_type ) {
    $block_editor = false;
  }
  return $block_editor;
}

/**
 * Exclude past events from the REST API and order the events by start date.
 */

add_filter( 'rest_event_query', __NAMESPACE__ . '\\rest_event_query', 10, 2 );

function rest_event_query( $args, $request ){
  $meta_query = array(
    'relation' => 'AND',
    array(
      'key' => '_event_start',
      'value' => date( 'Y-m-d' ),
      'compare' => '>=',
      'type' => 'DATE',
    ),
  );
  if( isset( $request['store'] ) ) {
    $meta_query[] = array(
      'key' => '_event_start',
      'value' => $request['store'],
      'compare' => '=',
    );
  }
  $args['meta_query'] = $meta_query;
  $args['orderby'] = 'meta_value';
  $args['meta_key'] = '_event_start';
  $args['order'] = 'ASC';
  return $args;
}