DataTables Server Side Processing in WordPress

DataTables Server Side Processing in WordPress (functions.php)

Add the following piece of code to your functions.php file.


add_shortcode('getMembership-lists', 'ajax_membership_table_shortcode');

// WITH AJAX LOAD TABLE
function membership_datatables_scripts() {
	wp_register_style('datatables_style', '//cdn.datatables.net/1.11.1/css/jquery.dataTables.min.css');
  	wp_enqueue_style('datatables_style');

	wp_register_script('datatables', '//cdn.datatables.net/1.11.1/js/jquery.dataTables.min.js', array('jquery'), true);
  	wp_enqueue_script('datatables');

	wp_enqueue_script( 'membership_datatables', get_stylesheet_directory_uri(). '/js/membershiptable.js', array(), '1.0', true );
	wp_localize_script( 'membership_datatables', 'ajax_url_membership', admin_url('admin-ajax.php?action=membership_datatables') );
}

function ajax_membership_table_shortcode() {
    membership_datatables_scripts(); 
    ob_start(); ?> 
	<div class="container-membership">
    <table id="membership" class="display compact table-membership" style="width:100%"> 
		<thead> 
			<tr> 
				<th>Membership Number</th>
				<th>Institute Name</th>
				<th>Email Address</th>
				<th>Contact Status Code</th> 
			</tr> 
		</thead> 
    </table> 
	</div>
    <?php return ob_get_clean(); 
}
add_action('wp_ajax_membership_datatables', 'datatables_server_side_callback');
add_action('wp_ajax_nopriv_membership_datatables', 'datatables_server_side_callback');


function datatables_server_side_callback() {
  header("Content-Type: application/json");
  $request= $_GET;

  $columns = array(
	0 => 'member_id',
    1 => 'post_title',
    2 => 'member_email',
    3 => 'member_code'
  );


  $args = array(
    'post_type' => 'member',
    'post_status' => 'publish',
    'posts_per_page' => $request['length'],
    'offset' => $request['start'],
    'order' => $request['order'][0]['dir'],
  );

  if ($request['order'][0]['column'] == 1) {
    $args['orderby'] = $columns[$request['order'][0]['column']];
  } else {
    $args['orderby'] = 'meta_value_num';
    $args['meta_key'] = $columns[$request['order'][0]['column']];
  }

  //$request['search']['value'] <= Value from search

  $search_val = $request['search']['value'];

  if( !empty($search_val) ) { // When datatables search is used
    $args['meta_query'] = array(
      'relation' => 'OR',
      array(
        'key' => 'd_title',
        'value' => sanitize_text_field($search_val),
        'compare' => 'LIKE'
      ),
      array(
        'key' => 'member_id',
        'value' => sanitize_text_field($search_val),
        'compare' => 'LIKE'
      ),
	  array(
        'key' => 'member_email',
        'value' => sanitize_text_field($search_val),
        'compare' => 'LIKE'
      ),
      array(
        'key' => 'member_code',
        'value' => sanitize_text_field($search_val),
        'compare' => 'LIKE'
      )
    );
  }

  $membership_query = new WP_Query($args);
  $totalData = $membership_query->found_posts;

  if ( $membership_query->have_posts() ) {
    while ( $membership_query->have_posts() ) {
      $membership_query->the_post();

      $nestedData = array();
	  $nestedData[] = get_field('member_id');
      $nestedData[] = get_the_title();
      $nestedData[] = get_field('member_email');
      $nestedData[] = '<span class="status">'.get_field('member_code').'</span>';

      $data[] = $nestedData;
    }
    wp_reset_query();

    $json_data = array(
      "draw" => intval($request['draw']),
      "recordsTotal" => intval($totalData),
      "recordsFiltered" => intval($totalData),
      "data" => $data
    );

    echo json_encode($json_data);
  } else {
    $json_data = array(
      "data" => array()
    );
    echo json_encode($json_data);
  }
  wp_die();
}




Source: 
- https://itsmereal.com/datatables-server-side-processing-in-wordpress/