Django: Reusable model filtering: Using QuerySet.as_manager() properly

models.py

# http://www.dabapps.com/blog/higher-level-query-api-django-orm/
# Converted to use Django 1.8 QuerySet.as_manager()

# We inherit custom QuerySet to define new methods
class TodoQuerySet(models.query.QuerySet):
    def incomplete(self):
        return self.filter(is_done=False)

    def high_priority(self):
        return self.filter(priority=1)


class Todo(models.Model):
    content = models.CharField(max_length=100)
    # other fields go here..

    objects = TodoQuerySet.as_manager()  # Activate custom QuerySet

zzz_example.py

# Now that we have a custom manager on Todo, we can chain filters
# e.g.

all = Todo.objects.all()
incomplete = Todo.objects.incomplete()
incomplete_hp = Todo.objects.incomplete().high_priority()

# This is super useful because it allows removing .filter(XXXXXXX)
# from View and improves maintainability in complex projects a lot.

The DabApps Ltd. article on inheriting QuerySet is great. It's written before Django got the .as_manager() method for QuerySet though and needs update. I'd use something like this gist instead.

The Django documentation Creating Manager with QuerySet methods example is not sufficient to explain this.

This example should be covered also by Django tutorial. In my opinion it's a best practice to avoid writing complex filters in views - they belong to models like this.