django - Django FormView：区分创建和更新

Question

我有一个自定义 FormView 类的 mixin，如果保存成功，它只会添加一条成功消息，所以：

class MessagesMixin(object):

    def form_valid(self, form):
        response = super(MessagesMixin, self).form_valid(form)
        messages.add_message(self.request,
                             messages.SUCCESS,
                             'Successfully created %s' % form.instance)
        return response

如您所见，这仅涵盖了创作。如果实例已更新，消息仍会显示“已创建”。有没有办法区分 form_valid 方法中的创建/更新？

Answer 1

一种解决方案是向您的 mixin 添加一个属性，然后在您的Update和Create视图中设置它。get_form_valid_msg如果您需要动态的东西，您可以定义静态属性或重载。未经测试的代码：

from django.core.exceptions import ImproperlyConfigured

class MessagesMixin(object): 
    @property
    def form_valid_msg(self):
        raise ImproperlyConfigured("you're missing the 'form_valid_msg' property")

    def get_form_valid_msg(self):
        return self.form_valid_msg

    def form_valid(self, form):
        response = super(MessagesMixin, self).form_valid(form)

        msg = 'Successfully {form_valid_msg} {form}'.format(
            form_valid_msg=self.get_form_valid_msg(),
            form=form.instance
        )

        messages.success(self.request, msg)

        return response