title: Pass initial value to a modelform in django
body: <p>How can I pass an initial value for a field to a model form. I have something like the following code </p>
  
  <pre><code>class ScreeningForm(forms.ModelForm):
      class Meta:
          model = Screening
  
      def __init__(self, *args, **kwargs):
          super(ScreeningForm, self).__init__(*args, **kwargs)
          self.fields['blood_screen_type'] =  CommaSeparatedCharField(
              label=self.fields['blood_screen_type'].label,
              initial=self.fields['blood_screen_type'].initial,
              required=False,
              widget=CommaSeparatedSelectMultiple(choices=BLOOD_SCREEN_TYPE_CHOICES)
          )
  
  class ScreeningAdmin(admin.ModelAdmin):
      #form = ScreeningForm
      form = ScreeningForm(initial={'log_user':get_current_user()})
  </code></pre>
  
  <p>Now I want to pass an initial value for a field of the Person class. How can I do that?</p>