Warning

dj-queryset-manager only works with Django versions 1.2 through 1.6.

In Django 1.7 it has been superseded by QuerySet.as_manager(). See the docs.

Usage

1. Create a manager class that inherit the QuerySetManager

2. Decorate your filter methods with queryset_method. These methods receive a queryset instead of a manager as the first argument.

from dj_queryset_manager import QuerySetManager, queryset_method

class MyManager(QuerySetManager):
    @queryset_method
    def by_slug(queryset, slug):
        return queryset.filter(slug=slug)

    @queryset_method
    def filter(queryset, *args, **kwargs):
        return super(type(queryset), queryset).filter(*args, **kwargs)

For reference, here is a standard implementation:

from django.db.models import Manager
from django.db.models.query import QuerySet

class MyQuerySet(QuerySet):
    def by_slug(self, slug):
        return self.filter(slug=slug)

    def filter(self, *args, **kwargs):
        return super(MyQuerySet, self).filter(*args, **kwargs)


class MyManager(Manager):
    def get_query_set(self): # Better remember the arguments to QuerySet
        QuerySet(self.model, using=self._db)

    def get_queryset(self): # And don't forget about Django 1.6
        return self.get_query_set()

    def by_slug(self, *args, **kwargs):  # Enjoy this duplicate signature
        return self.get_queryset().filter(*args, **kwargs)

Mix-in

Some third-party apps ship managers as part of their API. If you need to extend any existing manager, use the QuerySetManagerMixin. This example uses the InheritanceManager from django-model-utils.

from model_utils.managers import InheritanceManager
from dj_queryset_manager import QuerySetManagerMixin, queryset_method

class MyInheritanceManager(QuerySetManagerMixin, InheritanceManager):
    @queryset_method
    def by_slug(queryset, slug):
        return queryset.filter(slug=slug)

Installation

$ pip install dj-queryset-manager