title: Laravel: How do I validate a date ONLY if the date exists?
body: <p>I have a form, it has a date field called <code>starts</code>, which is optional:</p>
  
  <pre><code>...
  &lt;input type="date" name="starts"&gt;
  ...
  </code></pre>
  
  <p>Then I created a Request in Laravel that checks, among other things, if <code>starts</code> is a date, so the <code>rules()</code> function in the Request is somthing like:</p>
  
  <pre><code>public function rules()
  {
    return [
      ... (more validation rules)
      'starts'             =&gt; 'date',
      ... (more validation rules)
    ];
  }
  </code></pre>
  
  <p>So, when I submit the form and there's no <code>starts</code>, the validation rules kicks in, it says it's not a date, and returns to my form.</p>
  
  <p>How do I tell Laravel that <code>starts</code> is a date, only if it is present?</p>
  
  <p>I'm looking something like the validation in files, which only take place if there's a file present</p>