title: Specify choices in model and RadioButton in ModelForm renders not selected value "------"
body: <p>My goal is to be able to use get_FOO_display(), and so as far as I understand I will have to have choices specified in the model field. At the same time I am wanting to render the form using a ModelForm as a RadioButton.</p>
  
  <p>The problem I am having is that the default value of "------" that would be used in a dropdown select is showing up as one of my RadioButton options.</p>
  
  <p><strong>models.py</strong></p>
  
  <pre><code>class Medication(models.Model):
      YESNO_CHOICES = [(0, 'No'), (1, 'Yes')]
      Allergies = models.BigIntegerField(verbose_name='Allergies:', choices=YESNO_CHOICES)
  </code></pre>
  
  <p><strong>forms.py</strong></p>
  
  <p>I have tried just specifying a RadioButton widget in the ModelForm.</p>
  
  <pre><code>class mfMedication(ModelForm):
      class Meta:
          model = Medication
          widgets = {
          'Allergies': RadioSelect(),
          }
  </code></pre>
  
  <p>and also specifying the RadioButton with the CHOICES.</p>
  
  <pre><code>class mfMedication(ModelForm):
      class Meta:
          model = Medication
          widgets = {
          'Allergies': RadioSelect(choices=Medication.YESNO_CHOICES),
          }
  </code></pre>
  
  <p>In both cases I get three radiobuttons:</p>
  
  <pre><code>"": -------
  0 : No
  1 : Yes
  </code></pre>
  
  <p>The only way I do not get the "-------" is to remove choices=YESNO_CHOICES from my model field, but this stops get_FOO_display() from working.</p>
  
  <p>Any approach that you have used to get this working would be greatly appreciated. </p>
  
  <p>Thanks. JD.</p>