title: Can Laravel validation rule check a model record exists?
body: <p>I am having trouble to understand how the Laravel exists validation works in term of checking the existing record in the database.</p>
  
  <p>e.g.</p>
  
  <p><strong>POST request with user.id = 1</strong></p>
  
  <p>is that possible to use validation rule: 
  <code>'id' =&gt; 'exists:users'</code>
  to check the user 1 existed in the users table?</p>
  
  <p>Any good example will be good.</p>
  
  <p>Thanks,</p>