Combining Multiple QuerySets in Django with Examples

In Django, working with QuerySets is a fundamental aspect of database interaction. Sometimes, you may need to combine multiple QuerySets into one to create a unified and comprehensive result, in this blog, we will explore various techniques for combining QuerySets in Django, along with practical examples.

Using union()

The union() method in Django allows you to combine two or more QuerySets into single QuerySet while ensuring that duplicates are removed. This method is useful when you want to merge QuerySets that have the same structure.

Example 1: Combining QuerySets with union():

Let’s say you have two models, Author and Book, and you want to retrieve a combined list of authors and books:

from myapp.models import Author, Book

authors = Author.objects.all()
books = Book.objects.all()

combined_queryset = authors.union(books)

Using chain()

The chain() function from the itertools module allows you to concatenate multiple QuerySets together. Unlike union(), chain() does not remove duplicates

Example 2: Combining QuerySets with chain()

Suppose you have two models, Article and Comment and you want to combine the QuerySets without eliminating duplicates:

from myapp.models import Article, Comment
from itertools import chain

articles = Article.objects.all()
comments = Comment.objects.all()

combined_queryset = list(chain(articles, comments))

Using List Comprehension

You can manually combine QuerySets using list comprehension. This method gives you complete control over the combination process.

Example 3: Combining QuerySets with List Comprehension

Let’s say you have two QuerySets, queryset1 and queryset2, and you want to combine them:

queryset1 = MyModel.objects.filter(...)
queryset2 = MyModel.objects.filter(...)

combined_queryset = list(queryset1) + list(queryset2)

Using | (OR) Operator

Django QuerySets support the | operator, which allows you to combine QuerySets in readable and concise manner.

Example 4: Combining QuerySets with the | Operator

Suppose you have two QuerySets, queryset1 and queryset2, and you want to merge them:

queryset1 = MyModel.objects.filter(...)
queryset2 = MyModel.objects.filter(...)

combined_queryset = queryset1 | queryset2


Combining multiple QuerySets in Django is common task when building database-driven applications. Whether you need to merge QuerySets with or without duplicate removal, Django provides various methods and approaches to suit your requirements. By using union(), chain(), list comprehension, or the | operator, you can efficiently combine and manipulate QuerySets to create the desired results in your Django applications. Understanding these techniques is essential for working with data effectively and building versatile web applications