title: Filter multi-table inheritance in django
body: <p>I want to make a dynamic filter for multi-table inheritance.</p>
  
  <pre><code>class Product(models.Model):
      name ...
  
  class Product1(Product):
      color ...
  
  class Product2(Product):
      length ...
      tags = ManyToManyField('tags.Tag')
  </code></pre>
  
  <p>How to filter so as not to cause an exception "missing field"?</p>
  
  <pre><code>Product.objects.filter(***__color='11', ***__length='300', **__tags__pk__in=[1, 2])
  </code></pre>