class UserField(forms.EmailField):
def clean(self, value):
super(UserField, self).clean(value)
try:
User.objects.get(username=value)
raise forms.ValidationError("There is an existing account associated with this email.")
except User.DoesNotExist:
return value
метод try кроме простого. Тем не менее, мне трудно понять,
super(UserField, self).clean(value)