title: Grails criteria projections - get rows count
body: <p>I have Hotel entity:</p>
  
  <pre><code>class Hotel {
  City city
  }
  </code></pre>
  
  <p>Now, i need count of hotels with given city.
  It could be done in this way:</p>
  
  <pre><code>def hotels = Hotel.findAllByCity(city)
  def cnt = hotels.size()
  </code></pre>
  
  <p>But it's very <strong>dirty</strong> way. It seems that with criteria it would be better, but i have no idea how to implement it...</p>