title: Flask-restless - How to convert a DELETE request into an UPDATE
body: <p>What is the proper way to convert a DELETE request into an UPDATE?</p>
  
  <p>I am doing something like that:</p>
  
  <pre><code>api_manager.create_api(News,
                         methods=['GET', 'POST', 'DELETE', 'PUT'],
                         preprocessors={'DELETE': [pre_delete_news]})
  
  def pre_delete_news(instance_id=None, **kw):
      # Set the deleted flag
      db.engine.execute("SET delete = True FROM news WHERE id = %d" % instance_id)
      # Block the DELETE request by raising an exception
      raise ProcessingException(description='Delete successfull', code=418)
  </code></pre>
  
  <p>This is not very clean, because I raise an exception to force the blocking of the delete request.</p>