Django Custom Managers and Querysets Define custom managers
Example
Very often it happens to deal with models which have something like a published field. Such kind of fields are almost always used when retrieving objects, so that you will find yourself to write something like:
my_news = News.objects.filter(published=True)
too many times. You can use custom managers to deal with these situations, so that you can then write something like:
my_news = News.objects.published()
which is nicer and more easy to read by other developers too.
Create a file managers.py in your app directory, and define a new models.Manager class:
from django.db import models
class NewsManager(models.Manager):
def published(self, **kwargs):
# the method accepts **kwargs, so that it is possible to filter
# published news
# i.e: News.objects.published(insertion_date__gte=datetime.now)
return self.filter(published=True, **kwargs)
use this class by redefining the objects property in the model class:
from django.db import models
# import the created manager
from .managers import NewsManager
class News(models.Model):
""" News model
"""
insertion_date = models.DateTimeField('insertion date', auto_now_add=True)
title = models.CharField('title', max_length=255)
# some other fields here
published = models.BooleanField('published')
# assign the manager class to the objects property
objects = NewsManager()
Now you can get your published news simply this way:
my_news = News.objects.published()
and you can also perform more filtering:
my_news = News.objects.published(title__icontains='meow')
