title: Get all user's paperclip avatar url
body: <p>I am using rails 5 API and I am using paperclip to upload user's avatar. I have an index page of all users where I have to list all the users. I need a way to display all the users avatar</p>
  
  <p><code>@user.avatar.url</code> can be used to get one user's avatar.</p>
  
  <p>I could use</p>
  
  <pre><code>@users.each do |user|
      @avatar.push(user.avatar.url)
  end
  </code></pre>
  
  <p>Is there another way?
  Also, can I save the URL into an image field using a callback like <code>after_save</code> or <code>after_update</code> during user sign up?</p>