title: Generate order report by product name by WC_Admin_Report
body: <p>I want to generate an order report that ordered product contain specific name. </p>
  
  <p>For example I want sales report of product that has title "toy" , which the products includes "car toy", "tools toy" ,"bike toy"...etc.</p>
  
  <p>I want to use <code>Woocommerce WC_Admin_Report</code> class to generate the report, but I can't get it works. </p>
  
  <pre><code>include_once($woocommerce-&gt;plugin_path().'/includes/admin/reports/class-wc-admin-report.php');
  $wc_report = new WC_Admin_Report();
  
  $where_meta[] = array(
              'type' =&gt; 'order_item_meta',
              'meta_key' =&gt; '_product_name',
              'operator' =&gt; 'LIKE',
              'meta_value' =&gt; 'shirt'
          );
  
  $sold_products = $wc_report-&gt;get_order_report_data(array(
          'data' =&gt; array(
              '_product_id' =&gt; array(
                  'type' =&gt; 'order_item_meta',
                  'order_item_type' =&gt; 'line_item',
                  'function' =&gt; '',
                  'name' =&gt; 'product_id'
              ),
              '_qty' =&gt; array(
                  'type' =&gt; 'order_item_meta',
                  'order_item_type' =&gt; 'line_item',
                  'function' =&gt; 'SUM',
                  'name' =&gt; 'quantity'
              ),
              '_line_subtotal' =&gt; array(
                  'type' =&gt; 'order_item_meta',
                  'order_item_type' =&gt; 'line_item',
                  'function' =&gt; 'SUM',
                  'name' =&gt; 'gross'
              ),
              '_line_total' =&gt; array(
                  'type' =&gt; 'order_item_meta',
                  'order_item_type' =&gt; 'line_item',
                  'function' =&gt; 'SUM',
                  'name' =&gt; 'gross_after_discount'
              )
          ),
          'query_type' =&gt; 'get_results',
  
          'where_meta' =&gt; $where_meta,
  
          'limit' =&gt; 20,
  
          'order_status' =&gt; array( 'completed', 'processing')
      ));
  </code></pre>
  
  <p>The <code>where_meta</code> only looks for <code>woocommerce_order_itemmeta</code> table where the product name is in <code>woocommerce_order_items</code> table, so how can I make search through the <code>woocommerce_order_items</code> as well? Something like this?</p>
  
  <pre><code> $where_meta[] = array(
                  'type' =&gt; 'order_item',
                  'meta_key' =&gt; 'order_item_name',
                  'operator' =&gt; 'LIKE',
                  'meta_value' =&gt; 'toy'
              );
  </code></pre>