title: Django form field dynamic queryset field
body: <pre><code>class EventForm(forms.Form):
      date = forms.DateField(initial=datetime.date.today)
      product = forms.ModelMultipleChoiceField(queryset=Product.objects.all())
      isrecurring = forms.BooleanField(required=False)
      week =  forms.IntegerField(required=False, initial=1)
      days =  forms.ChoiceField(choices = week_days,required=False)
  </code></pre>
  
  <p>I have a form that has a products field which is a query set of all products.</p>
  
  <p>I want the field to filter products by company.</p>
  
  <p>How can i set the form field to have dynamically queryset in the view such that the products are filtered based on the company id?</p>
  
  <pre><code>product = forms.ModelMultipleChoiceField(queryset=Product.objects.filter(company=xyz))
  </code></pre>