title: Django: Maintainable drop down choices
body: <p>I have a newbie problem(sorry for the bad english).</p>
  
  <p>I am trying to make a maintainable drop down choices on the address part of my project.</p>
  
  <p>Let's say that I have these models:</p>
  
  <pre><code>class STATES(models.Model):
      state= models.CharField(max_length=255)
  
  class CITIES(models.Model):
      fkey = models.ForeignKey(STATES)
      CITY = models.CharField(max_length=255)
  
      def __unicode__(self):
          return self.CITY
  </code></pre>
  
  <p>And forms</p>
  
  <pre><code>class address(ModelForm):
      state = forms.ModelChoiceField(queryset = STATES.objects.all())
      CITY = forms.ModelChoiceField(queryset = CITIES.objects.all())
  class Meta:
      model = REGIONS
      fields = ('state', 'CITY',)
  </code></pre>
  
  <p>How do i make the form display the cities that is in the state that I selected?</p>
  
  <p>Any pointers, advice, links, or even a sample code would be much appreciated.</p>
  
  <p>Thanks in advance</p>