DjNRO

    def clean_ertype(self):

        ertype = self.cleaned_data['ertype']

        institution = self.cleaned_data['instid']

        inst_type = institution.institutiondetails.ertype

        type_list = [inst_type]

        if inst_type == 3:

            type_list = [1, 2, 3]

        if ertype:

            if ertype not in type_list:

                raise forms.ValidationError('Server type cannot be different than institution type (%s)' %dict(self.fields['ertype'].choices)[inst_type])

            return self.cleaned_data["ertype"]

        else:

            raise forms.ValidationError('This field is required.')