title: Woocommerce: get the shiping postal code to calculate shipping cost
body: <p>I'm developing a new shipping method that calculates the rate based on the package weight, volume and customers zip code... 
  Ive had no problem retrieving the cart information on the calculate_shipping function, but when I try to retrieve the zip code from customer it seems to return an empty value.
  how can I retrieve this information on runtime in order to calculate the final cost?</p>
  
  <pre><code>public function calculate_shipping( $package ) { 
      GLOBAL $woocommerce; 
      $items = $woocommerce-&gt;cart-&gt;get_cart(); 
      $cliente = $woocommerce-&gt;customer;  
      $peso = $woocommerce-&gt;cart-&gt;cart_contents_weight; 
      $customer_postcode = $woocommerce-&gt;customer-&gt;get_shipping_postcode(); 
  }
  </code></pre>
  
  <p>Solved:</p>
  
  <p><code>$customer_postcode = get_user_meta( get_current_user_id(), 'shipping_postcode', true );</code></p>