title: Woocommerce REST API - Bookings product import
body: <p>I've been trying to import products with the Woocommerce REST API (v2). 
  Goes great, except when it comes to the 'booking extension' fields. Those are pretty much all underscored (so 'protected') and they won't insert into the postmeta table.</p>
  
  <p>Well actually... they DO, but then Woocommerce's 'apply_filters()' comes around and adapts all entries (doesn't remove rows, simply alters them...).</p>
  
  <p>Has anybody got a (preferably simple) solution to this?
  I need to insert about 20 _rows for each product and this has been bothering me for weeks now.</p>
  
  <p>So, summarized:</p>
  
  <ul>
  <li>Create or update product throught API: works great</li>
  <li>api calls all have the ['meta_data'] array, those DO get inserted. If I exit the script just before the apply_filters() in /wp-content/plugins/woocommerce/includes/api/class-wc-rest-products-controller.php they are still in my database!!</li>
  <li>then apply_filters() runs and most values are made empty or reverted to some default state</li>
  </ul>
  
  <p>I tried to simply disable 'apply_filters()', but ofc that's a bad solution and it doesn't work.</p>
  
  <p>There must be more people wanting to simply add _metadata_items on the fly to their postmeta table ?!</p>