title: Laravel 5.6 - Only save value if it has changed
body: <p>I have a Laravel 5.6 project and am trying to update a post from a form like this</p>
  
  <pre><code>&lt;input name="email" type="text" class="form-control" placeholder="Email" value="{{$user-&gt;email}}" required&gt;
  </code></pre>
  
  <p>In my PostsController I have this...</p>
  
  <pre><code>    if($request-&gt;input('email')) {
          $user-&gt;email = $request-&gt;input('email');
      }
  </code></pre>
  
  <p>I wanted it to only update the email if a new one has been input in the form, but because I am pre-populating the form fields it always passes the IF.</p>
  
  <p>Is there a more Laravel way to do this? I have looked at isDirty() but I am not sure it is the correct thing to use.</p>