title: Django Success_url
body: <p>I built a FormView with two fields in it.  I want to use the form to pass queries to a view.</p>
  
  <pre><code>class SectorForm(forms.Form):
      date = forms.DateField()
      days = forms.IntegerField(max_value=365, min_value=1)
  </code></pre>
  
  <p>Is there a way I can take my FormView and build the <strong>success_url</strong> from the valid form fields?</p>
  
  <p>So overriding the get_success_url.</p>
  
  <pre><code>      def get_success_url(self): 
          return reverse_lazy('queryable-view' date days)
  </code></pre>
  
  <p>I thought I could pull it out from form_valid but never had success.   </p>