dj-queryset-manager 0.1.1

Stop writing Django querysets.

A Django utility that makes it simple to write DRY queryset methods.

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)

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)

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)

Planned Obsolescence

This project will be partially obsoleted by Django 1.7, when you can do this:

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

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

MyManager = Manager.from_queryset(MyQuerySet)

However, if you still need to extend existing managers, or you don’t want to worry about the upgrade path from Manager.get_query_set to Manager.get_queryset in your own code, you may want to stick with this package.

Installation

$ pip install dj-queryset-manager