title: Laravel not adhering to Mass Assignment $fillable rules for related model update
body: <p>I have <code>business</code> and <code>profile</code> models in my Laravel app. A business <code>hasOne</code> profile.
  I've created a patch method form using the form builder to update my business and profile tables.</p>
  
  <p>Blade</p>
  
  <pre><code>{!! Form::model($business, ['route' =&gt; ['business.edit.post', $business], 'method' =&gt; 'PATCH']) !!}
                  @include('forms.business.edit')
  {!! Form::close() !!}
  </code></pre>
  
  <p>BusinessController</p>
  
  <pre><code>public function update(Request $request, $id)
  {
      $business = Business::findOrFail($id);
  
      $business-&gt;update($request-&gt;all());
      $business-&gt;profile()-&gt;update($request-&gt;all());        
  
      return back()-&gt;withMessage('updated');
  }
  </code></pre>
  
  <p>Now using a patch method will include a hidden field called _method along with the built in _token field for csrf protection.
  I am getting an error when it updates the <code>profile</code> model stating:</p>
  
  <pre><code>SQLSTATE[42S22]: Column not found: 1054 Unknown column '_method' in 'field list' (SQL: update `business_profiles` set `_method` = PATCH, `_token` = Zyxtxa88uUQKhaRQNY8k7qPu2N0i6o20dY4sUABk, `city` = Belfast where `business_profiles`.`business_id` = 107 and `business_profiles`.`business_id` is not null)
  </code></pre>
  
  <p>It appears to me its trying to update those hidden fields when it shouldn't. When commenting out the _<code>profile-&gt;update</code> line the save works fine. It looks like updating related Models does not adhere to the mass assignment rules built into Laravel. Could someone advise how to fix this?</p>