title: django render initial values in form with ModelMultipleChoiceField and CheckboxSelectMultiple() widget
body: <p>I have the following form:</p>
  
  <pre><code>class TutorForm(SignupForm):
     subjects = forms.ModelMultipleChoiceField(queryset=Subject.objects.all(),
                                            widget=forms.CheckboxSelectMultiple())
  </code></pre>
  
  <p>I have a child form called <code>TutorUpdateForm</code>that inherits from <code>TutorForm</code> and it sets initial values in init method.</p>
  
  <pre><code>self.fields['subjects'].initial = current_user.subjects.all()
  </code></pre>
  
  <p>In my template however the values are not checked (in views the values are there, so setting initial values works). How can I enforce checked inputs in the template?</p>
  
  <p><strong>EDIT (init code)</strong></p>
  
  <pre><code>def __init__(self, *args, **kwargs):
      current_user = None
      try:
          current_user = kwargs.pop('user')
      except Exception:
          pass
      super(TutorUpdateForm, self).__init__(*args, **kwargs)
  
      for field in _update_exclude:
          self.fields.pop(field)
  
      if current_user:
          self.fields['subjects'].initial = current_user.subjects.all()
  </code></pre>