ChainableManager for Django

chainable_manager.py

# -*- coding: utf-8 -*-
from django.db import models
from django.db.models.query import QuerySet


class ChainableManager(models.Manager):
    """
    class MyChainableManager(ChainableManager):
        def active(self):
            return self.filter(active=True)
            
        def inactive(self):
            return self.filter(active=False)
        
        def cool(self):
            return self.filter(cool=True)
            
        def lame(self):
            return self.filter(cool=False)
    
    class MyModel(models.Model):
        active = models.BooleanField()
        cool = models.BooleanField()
        
        objects = MyChainableManager()
    
    MyModel.objects.active().cool() # get all cool active items
    MyModel.objects.inactive().lame().delete() # delete all inactive-lame items
    """
    def get_query_set(self):
        queryset_class = type('ChainedQuerySet', (QuerySet, self.__class__,), {})
        return queryset_class(self.model, using=self._db)