Manager isn't accessible via model instances

user_468151 0
Viewed 97602

I'm trying to get model objects instance in another one and I raise this error :

 Manager isn't accessible via topic instance

Here's my model :

class forum(models.Model):
    # Some attributs

class topic(models.Model):
    # Some attributs

class post(models.Model):
    # Some attributs

    def delete(self):
        forum = self.topic.forum
        super(post, self).delete()
        forum.topic_count = topic.objects.filter(forum = forum).count()

Here's my view :

def test(request, post_id):
    post = topic.objects.get(id = int(topic_id))
    post.delete()

And I get :

post.delete()
forum.topic_count = topic.objects.filter(forum = forum).count()
Manager isn't accessible via topic instances
django-managers instance django-models django
6 Answers

For django < 1.10

topic._default_manager.get(id=topic_id)

Though you should not use it like this. The _default_manager and _base_manager are private, so it's recomended to use them only if you're inside the Topic model, like when you want to use the Manager in a proprietary function let's say:

class Topic(Model):
.
.
.
    def related(self)
        "Returns the topics with similar starting names"
        return self._default_manager.filter(name__startswith=self.name)

topic.related() #topic 'Milan wins' is related to:
# ['Milan wins','Milan wins championship', 'Milan wins by one goal', ...]
user_6489040

I just had an issue similar to this error. And looking back at your code it seems that it could be your issue too. I think your issue is that your comparing "id" to "int(topic_id)" and topic_id is not set.

def test(request, post_id):
    post = topic.objects.get(id = int(topic_id))
    post.delete()

I'm guessing your code should use "post_id" not "topic_id"

def test(request, post_id):
    post = topic.objects.get(id = int(post_id))
    post.delete()
user_102980710
Related