title: Rails - how to update model without required items
body: <p>I have a model that contains required and free fields. Between the required items is also item with password.</p>
  
  <p>In the <strong>_form.html.erb</strong> I hid the input with a password, so when the user want to update the form, so he will be update the all items except password => that's what I want. But because the item <strong>password</strong> is require, so I will get an error about bad validations.</p>
  
  <p>I would like to ask you, if exist a good way to do this... I can't find some trick for it</p>