title: Best practice for DRYing up New and Edit forms using partial
body: <p>This should be an easy one, I'm a noob.</p>
  
  <p>I have new and edit views for a model that use a partial to display a form. For the edit form I want to display a field that I do not want to display in the new form.</p>
  
  <p>Should I be passing a local variable stating its in edit mode to the partial and use a condition in the partial to display the field?</p>
  
  <p>Whats the best practice in this case to let the partial know what action called it?</p>