Django: AttributeError when calling native model method

I recently added a new method to my News model:

def slug(self):
    return slugify(self.title)

      

        
        
        
      

    

However, I cannot name it anywhere. Imagine I have a News object called n. When trying to call

n.slug()

      

        
        
        
      

    

I always get an error like:

AttributeError: 'News' object has no attribute 'slug'

      

        
        
        
      

    

I'm new to Django and Python and I'm pretty sure this is just a stupid mistake on my side. BTW, I tried restarting the dev server and syncing the db after I added this method, both don't change anything. Note that I have used model methods like this with no problem: S

Edit:

Here's the model:

from django.template.defaultfilters import slugify

class News(models.Model):
    title = models.CharField(max_length=100)
    [...]
    def slug(self):
        return slugify(self.title)

      

        
        
        
      

    

Here is some sample code for how I call the method. At first I tried to call it a pattern, but it didn't work. Then I changed my view so that it just returns the slug, but the error remains. The same when I try to use it in the shell.

from fbki.models import News

def news_detail(request, slug, news_id):
    news = News.objects.get(id = news_id)
    return HttpResponse(news.slug())