title: Displaying a specific object field in ChoiceField
body: <p>I've got a ChoiceField in my form. The options that appear in the dropdown are equal to "industry name - frequency" (eg. Car Maintenance - Annual). I want the options in the dropdown to only be equal to the value in the frequency field of the choices that I initialize (eg. Annual).</p>
  
  <p><strong>Models.py</strong></p>
  
  <pre><code>class IndustryFrequency(models.Model):    
      industryname = models.ForeignKey(Industry, on_delete=models.CASCADE)
      frequency = models.CharField()
  
      def __str__(self):
          return '{} - {}'.format(self.industryname, self.frequency)
  </code></pre>
  
  <p><strong>Forms.py</strong></p>
  
  <pre><code>class UserOrderForm(forms.Form):
      frequency = forms.ChoiceField()
  
      def __init__(self, *args, **kwargs):
          super(UserOrderForm, self).__init__(*args, **kwargs)
          self.fields['frequency'].choices = [(t.id, t) for t in IndustryFrequency.objects.filter(industryname=industry)]
  </code></pre>
  
  <p>Thanks for your help!</p>