Django Custom Managers and Querysets select_related for all queries
Example
Model with ForeignKey
We will work with these models :
from django.db import models
class Book(models.Model):
name= models.CharField(max_length=50)
author = models.ForeignKey(Author)
class Author(models.Model):
name = models.CharField(max_length=50)
Suppose we often (always) access book.author.name
In view
We could use the following, each time,
books = Book.objects.select_related('author').all()
But this is not DRY.
Custom Manager
class BookManager(models.Manager):
def get_queryset(self):
qs = super().get_queryset()
return qs.select_related('author')
class Book(models.Model):
...
objects = BookManager()
Note : the call to super must be changed for python 2.x
Now all we have to use in views is
books = Book.objects.all()
and no additional queries will be made in template/view.
