all() and filter() methods in Django

Introduction

The all() and filter() methods help you get data from your database easily. They let you find all records or only the ones you want.

When you want to get every item from a database table.

When you want to find items that match certain rules, like all users with age over 18.

When you want to show a list of filtered results on a webpage.

When you want to check if some data exists by filtering with conditions.

Syntax

Django

ModelName.objects.all()
ModelName.objects.filter(field_name=value)

all() returns all records from the database table.

filter() returns only records that match the conditions you give.

Examples

Gets all books from the Book table.

Django

Book.objects.all()

Gets users who are 18 years old or older.

Django

User.objects.filter(age__gte=18)

Gets products in the 'toys' category that are in stock.

Django

Product.objects.filter(category='toys', in_stock=True)

Sample Program

This example shows how to get all users and then only users who are 18 or older. It prints their names to the console.

Django

from django.db import models

class User(models.Model):
    name = models.CharField(max_length=100)
    age = models.IntegerField()

# Imagine we have these users in the database:
# User(name='Alice', age=25)
# User(name='Bob', age=17)
# User(name='Charlie', age=30)

# Get all users
all_users = User.objects.all()

# Get users aged 18 or older
adult_users = User.objects.filter(age__gte=18)

# Print names of all users
print('All users:')
for user in all_users:
    print(user.name)

# Print names of adult users
print('\nAdult users:')
for user in adult_users:
    print(user.name)

Important Notes

Use filter() to narrow down results with conditions.

Both methods return QuerySets, which act like lists but get data only when needed.

You can chain filters for more complex queries, like .filter(age__gte=18).filter(name__startswith='A').

Summary

all() gets every record from a table.

filter() gets records that match your conditions.

Use these methods to easily find and work with data in Django.