title: Get all field names from magento model
body: <p>How can I get all field names from an object like "order" without creating or loading this object?</p>
  
  <p>Example:</p>
  
  <pre><code>Model: sales/order
  </code></pre>
  
  <p>With a loaded order and the getData() method I get an array of various field names like:</p>
  
  <pre><code>shipping_tax_amount
  grand_total
  base_tax_amount
  </code></pre>
  
  <p>How can I get these field names without an order? In my case it must be possible to access to this fields even if there is no order at the magento shop.</p>