title: How to allow Users to sign up without password until later, using Devise?
body: <p>In my project Users can sign up with just an email address (no password) and have limited access to the site. I want to add functionality so Users can later choose to set a password using Devise. Then parts of the site would require authentication for access. </p>
  
  <p>(By way of example, on Craigslist you can post with just your email, but you have the option to create an account with email/password to access your past listings).</p>
  
  <p>Using Devise on the User model, how can this be done? If I try to create a user without a password, Devise of course complains "password can't be blank". </p>
  
  <p>A possible solution is to have two different models, for example User (email only) and Member (email and password), but I'm not sure it's ideal since the only difference between a User and a Member is that members have set a password. </p>
  
  <p>Another possible solution would be to randomly generate a password and save that without telling the user. Then when they do want to create a password, force a password reset. But I'm not sure that's a good practice. </p>
  
  <p>Thanks for any guidance you can provide. </p>
  
  <p>Rails 4
  Ruby 2.1.4</p>