Django: Signal callback function missing foreign on model
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.Mode开发者_如何学Pythonl):
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?
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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