Question: I'm working on a Django project and I'm trying to calculate the total number of likes for a user based on their posts (i.e if a user has post with 10 likes and another with 5, the total likes must display 15) . I've tried various approaches, but I haven't been able to get it working. Here is my models.py: class User(AbstractUser): username = models.CharField(...) first_name = models.CharField(...) last_name = models.CharField(...) email = models.EmailField(...) bio = models.CharField(...) ... class Post(models.Model): author = models.ForeignKey(User, null=True, on_delete=models.SET_NULL) text = models.CharField(max_length=280) created_at = models.DateTimeField(auto_now_add=True) likes = models.ManyToManyField(User, related_name="user_post") def total_likes(self): return self.likes.count() class Meta: ordering = ["created_at"]  And here I am trying to display the total number of likes for all posts from a specific user inside this html file (user profile): ... <p>Total likes: {{ post.likes.all.count }} </p> ...  views.py  @login_required def show_user(request, user_id): try: user = User.objects.get(id=user_id) posts = Post.objects.filter(author=user) except ObjectDoesNotExist: return redirect('user_list') else: return render(request, 'show_user.html', {'user': user , 'posts' : posts, 'request_user': request.user})  Here's what I've tried so far:  Initially, I attempted to use the {{ post.likes.all.count }} template tag to display the total number of likes for each post. However, this didn't work as it didn't return any value on the screen.  Next, I tried using the {% add %} template tag within a loop to iterate over all the posts and accumulate the likes count. However, this resulted in a TemplateSyntaxError.   I am not sure what the best way to solve this issue is. I would greatly appreciate any guidance or suggestions on how to calculate and display the total number of likes for a user's from all posts in Django.

Answer: You can determine the total number of likes for an author with: from django.db.models import Count @login_required def show_user(request, user_id): user = get_object_or_404( User.objects.annotate(total_likes=Count('post__likes')), pk=user_id ) posts = Post.objects.filter(author=user) return render( request, 'show_user.html', {'user': user, 'posts': posts, 'request_user': request.user}, ) in the template you can then render the total likes of the user with: {{ user.total_likes }} You can also boost counting the number of likes per post with: from django.db.models import Count @login_required def show_user(request, user_id): user = get_object_or_404( User.objects.annotate(total_likes=Count('post__likes')), pk=user_id ) posts = Post.objects.annotate(num_likes=Count('likes')).filter(author=user) return render( request, 'show_user.html', {'user': user, 'posts': posts, 'request_user': request.user}, ) In the template you can then render this with: {% for post in posts %} {{ post }} (likes: {{ post.num_likes }}) {% endfor %}   Note: It is often better to use get_object_or_404(…) [Django-doc], then to use .get(…) [Django-doc] directly. In case the object does not exists, for example because the user altered the URL themselves, the get_object_or_404(…) will result in returning a HTTP 404 Not Found response, whereas using .get(…) will result in a HTTP 500 Server Error.    Note: It is normally better to make use of the settings.AUTH_USER_MODEL [Django-doc] to refer to the user model, than to use the User model [Django-doc] directly. For more information you can see the referencing the User model section of the documentation.