form下拉、checkbox继承设置

当遇到从数据库读取一些，choice选项时可以用继承的方法

class ArticleForm(django_forms.Form):
    def __init__(self, request, *args, **kwargs):
        super(ArticleForm, self).__init__(*args, **kwargs)
        blog_id = request.session['user_info']['blog__nid']
        self.fields['category_id'].choices = models.Category.objects.filter(blog_id=blog_id).values_list('nid',
                                                                                                         'title')
        self.fields['tags'].choices = models.Tag.objects.filter(blog_id=blog_id).values_list('nid', 'title')