title: Laravel: Check input field is empty or not submitted
body: <p>I have multiple forms on different sites. They all end in the same route.
  The user has the ability to set some types of a model on null.
  Not every form submits all fields of the model. So for example:</p>
  
  <p>Model has this fields: <code>Name, Adress, Phone, Text</code></p>
  
  <p>Form 1 submits <code>Name, Adress, Phone</code></p>
  
  <p>Form 2 submits <code>Adress, Text</code></p>
  
  <p>If I submit form 1, my model would look like this:</p>
  
  <pre><code>$model-&gt;name = Name;
  $model-&gt;adress = Adress;
  $model-&gt;phone = Phone;
  $model-&gt;text = null;
  </code></pre>
  
  <p>But I dont want to overwrite Text. I want Text to be the value it was before the submit. But if I submit form 2, I want to change text or even set it to null.</p>
  
  <p>However, how can I check if a form name was in the submitted form (even if it is actually <code>null</code>)?</p>
  
  <p>Curently, this is my update Routine in my controller:</p>
  
  <pre><code>...
  $this-&gt;artSkill = ($request-&gt;artSkill) ? $request-&gt;artSkill : null;
  $this-&gt;craftsmanSkill = ($request-&gt;craftsmanSkill) ? $request-&gt;craftsmanSkill : null;
  $this-&gt;ownInitiativeSkill = ($request-&gt;ownInitiativeSkill) ? $request-&gt;ownInitiativeSkill : null;
  ...
  </code></pre>