title: Doctrine Criteria - concatenating inside a Criteria
body: <p>I'm trying to filter out claims from a collection where the claim date is earlier than 2016-01-01. Doctrine is not allowing me to do this sort of concatenation. Does anyone have an idea how I can achieve the desired results?</p>
  
  <pre><code>public function getItems()
  {
      $criteria = Criteria::create()
          -&gt;where(Criteria::expr()-&gt;gte('year' . '-' . 'month' . '-01', '2016-01-01));
  
      return $this-&gt;items ? $this-&gt;items-&gt;matching($criteria) : null;
  }
  </code></pre>
  
  <p>The error I'm getting looks like this:</p>
  
  <pre><code>ORMException in ORMException.php line 101:
  Unrecognized field: year-month-01
  </code></pre>