Django：模型上缺少外部信号回调函数

发布于 2024-10-12 16:07:41 字数 1383 浏览 2 评论 0原文

嘿，我试图让信号 pre_save 在我的模型上工作，但是有似乎是外键或其他问题。我的模型是像这样：

class BlogEntry(models.Model):
    headline = models.CharField(max_length=100)
    content = models.CharField(max_length=2000)
    written_by = models.ForeignKey(User)
    date = models.DateTimeField(auto_now=True)
    project = models.ForeignKey(Project)

这是处理和保存表单的地方：

    def form_valid(self, blogform): # post a blogentry
        blog_entry = blogform.save(commit=False)
        blog_entry.written_by = self.request.user
        blog_entry.project = blog_entry.project #debugging shows that this
    is a valid instance of the Project model
        blog_entry.save()

    return TemplateResponseMixin.render_to_response(self,
self.get_context_data())

这是我的信号接收器函数

@receiver(post_save, sender=BlogEntry)
def project_blog_entry_signal(sender, **kwargs):
    log = Log()
    log.project = sender.project.field
    log.content_type = Log.content_new_blogentry
    log.save()

这是例外：

<块引用>
无法分配 “django.db.models.fields.lated.ForeignKey 对象位于 0x21eef86c": "Log.project" 必须是“项目”实例。
@线--->日志.项目 = sender.project.field 位于
<块引用>
project_blog_entry_signal() 函数

发送者对象似乎没有将项目作为模型实例传递，而是作为外键实例传递。这是为什么？

原文

Hey,
Im trying to get the signal pre_save to work on my model but there
seems to be some problem with a foreign key or something. My model is
like this:

class BlogEntry(models.Model):
    headline = models.CharField(max_length=100)
    content = models.CharField(max_length=2000)
    written_by = models.ForeignKey(User)
    date = models.DateTimeField(auto_now=True)
    project = models.ForeignKey(Project)

And here is where the form is processed and saved:

    def form_valid(self, blogform): # post a blogentry
        blog_entry = blogform.save(commit=False)
        blog_entry.written_by = self.request.user
        blog_entry.project = blog_entry.project #debugging shows that this
    is a valid instance of the Project model
        blog_entry.save()

    return TemplateResponseMixin.render_to_response(self,
self.get_context_data())

And here's my signal reciever function

@receiver(post_save, sender=BlogEntry)
def project_blog_entry_signal(sender, **kwargs):
    log = Log()
    log.project = sender.project.field
    log.content_type = Log.content_new_blogentry
    log.save()

And here's the exception:

Cannot assign
"django.db.models.fields.related.ForeignKey
object at 0x21eef86c": "Log.project"
must be a "Project" instance.
@the line ---> log.project =
sender.project.field in
project_blog_entry_signal() function

The sender object doesn't seem to pass the project as a model instance but rather as a Foreign key instance. Why is that?

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伤感在游骋 2024-10-19 16:07:41

解决了。 “sender”参数只是一个类对象，而不是一个实例。在我的回调中，我可以通过 kwargs 引用实例，例如：
blog_entry_instance = kwargs["instance"]

因此回调函数将如下所示：

@receiver(post_save, sender=BlogEntry)
def project_blog_entry_signal(sender, **kwargs):
    log = Log()
    log.project = kwargs["instance"].project
    log.content_type = Log.content_new_blogentry
    log.save()

Solved it. The 'sender' argument is just a class object, not an instance. In my callback I can reference the instance by the kwargs like:
blog_entry_instance = kwargs["instance"]

So the callback function would look like this:

@receiver(post_save, sender=BlogEntry)
def project_blog_entry_signal(sender, **kwargs):
    log = Log()
    log.project = kwargs["instance"].project
    log.content_type = Log.content_new_blogentry
    log.save()

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