title: Is there a Djangonic way to get Django objects from a list defaulting to all() if the list is empty?
body: <p>For example something like <code>MyModel.objects.filter(some_value___in=[1,2], ignore_null_some_value=True)</code> would return MyModels with some_values 1 or 2, but <code>MyModel.objects.filter(some_value__in=[], ignore_null_some_value=True)</code> would return all instances of MyModel?</p>
  <p>My best effort so far is to do a second db query earlier to make sure the list is populated, e.g.:</p>
  <pre><code>values = &lt;list&gt; or MyModel.objects.values_list('some_value', flat=True))
  MyModel.objects.filter(some_value__in=values)
  </code></pre>
  <p>But this feels inefficient.</p>