title: Django annotate data by date for empty result
body: <p>Suppose I have a object model A, and it has a field called created, which is a datetime type field. </p>
  
  <p>If I use annotate to count how many A are created each day, I can use</p>
  
  <pre><code>A.objects.annotate(date=Trunc('created', 'day', output_field=DateField()) ).values('date').order_by('date').annotate(count=Count('id'))
  </code></pre>
  
  <p>After that, I can get the result, which looks like</p>
  
  <pre><code>[{date: '2018-07-22', count:1 }, {date: '2018-07-23', count:1 }, {date: '2018-07-25', count:1 }]
  </code></pre>
  
  <p>However, notice that I miss a 2018-07-24 because it didn't create any A in that day. Is there any way to let result to have <code>{date: '2018-07-24', count:0 }</code> inside that queryset?</p>