Django 4.2 LTS: Key Features

Django 4.2 LTS provides three years of security updates, making it ideal for enterprise applications. New features improve database handling and developer experience. At ZIRA Software, we standardize on LTS releases for production stability.

LTS Support Timeline

Django 4.2 LTS
├── Release: April 2023
├── Security Support: Until April 2026
└── Extended Support: 3 years total

Recommended for:
├── Production applications
├── Enterprise deployments
└── Long-term projects

Installation

pip install Django>=4.2,<5.0

# Or specific version
pip install Django==4.2.7

Psycopg 3 Support

# settings.py - Using Psycopg 3
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': 'mydb',
        'USER': 'user',
        'PASSWORD': 'password',
        'HOST': 'localhost',
        'PORT': '5432',
        'OPTIONS': {
            'pool': True,  # Connection pooling (Psycopg 3)
        },
    }
}

# Install Psycopg 3
# pip install psycopg[binary,pool]

Psycopg 3 benefits:

• Native async support
• Connection pooling
• Better performance
• Modern Python typing

Database Column Comments

# models.py
from django.db import models

class Product(models.Model):
    sku = models.CharField(
        max_length=50,
        db_comment='Stock Keeping Unit - unique product identifier'
    )
    price = models.DecimalField(
        max_digits=10,
        decimal_places=2,
        db_comment='Product price in USD, excluding tax'
    )
    created_at = models.DateTimeField(
        auto_now_add=True,
        db_comment='Timestamp when product was first added to catalog'
    )

    class Meta:
        db_table_comment = 'Product catalog with pricing and inventory data'

-- Generated SQL
COMMENT ON TABLE products IS 'Product catalog with pricing and inventory data';
COMMENT ON COLUMN products.sku IS 'Stock Keeping Unit - unique product identifier';

Constraint Validation Improvements

from django.db import models
from django.db.models import Q, CheckConstraint, UniqueConstraint

class Order(models.Model):
    status = models.CharField(max_length=20)
    total = models.DecimalField(max_digits=10, decimal_places=2)
    discount = models.DecimalField(max_digits=10, decimal_places=2, default=0)

    class Meta:
        constraints = [
            # Check constraint with validation
            CheckConstraint(
                check=Q(discount__lte=models.F('total')),
                name='discount_lte_total',
                violation_error_message='Discount cannot exceed order total',
            ),
            # Unique constraint with condition
            UniqueConstraint(
                fields=['status'],
                condition=Q(status='processing'),
                name='single_processing_order',
                violation_error_message='Only one order can be processing at a time',
            ),
        ]

Async ORM Improvements

# views.py - Async view with ORM
from django.http import JsonResponse

async def dashboard_stats(request):
    # Async aggregation
    from django.db.models import Sum, Count

    stats = await Order.objects.filter(
        status='completed'
    ).aaggregate(
        total_revenue=Sum('total'),
        order_count=Count('id'),
    )

    # Async iteration
    recent_orders = []
    async for order in Order.objects.filter(
        created_at__gte=timezone.now() - timedelta(days=7)
    ).order_by('-created_at')[:10]:
        recent_orders.append({
            'id': order.id,
            'total': str(order.total),
        })

    return JsonResponse({
        'stats': stats,
        'recent_orders': recent_orders,
    })

Transaction Handling

from django.db import transaction

# Durable transactions
@transaction.atomic(durable=True)
def process_payment(order_id):
    order = Order.objects.select_for_update().get(id=order_id)
    # Process payment...
    order.status = 'paid'
    order.save()

# Async transactions
async def async_create_order(data):
    async with transaction.atomic():
        order = await Order.objects.acreate(**data)
        await OrderItem.objects.abulk_create([
            OrderItem(order=order, **item)
            for item in data['items']
        ])
        return order

File Storage Improvements

# settings.py
STORAGES = {
    'default': {
        'BACKEND': 'django.core.files.storage.FileSystemStorage',
    },
    'staticfiles': {
        'BACKEND': 'django.contrib.staticfiles.storage.StaticFilesStorage',
    },
    's3': {
        'BACKEND': 'storages.backends.s3boto3.S3Boto3Storage',
        'OPTIONS': {
            'bucket_name': 'my-bucket',
        },
    },
}

# Usage in models
class Document(models.Model):
    file = models.FileField(storage='s3')

Management Command Improvements

# management/commands/process_orders.py
from django.core.management.base import BaseCommand

class Command(BaseCommand):
    help = 'Process pending orders'

    def add_arguments(self, parser):
        parser.add_argument(
            '--batch-size',
            type=int,
            default=100,
            help='Number of orders to process per batch',
        )

    def handle(self, *args, **options):
        batch_size = options['batch_size']

        # Progress output
        orders = Order.objects.filter(status='pending')
        total = orders.count()

        self.stdout.write(f'Processing {total} orders...')

        for i, order in enumerate(orders.iterator(chunk_size=batch_size)):
            self.process_order(order)

            if (i + 1) % batch_size == 0:
                self.stdout.write(f'Processed {i + 1}/{total}')

        self.stdout.write(
            self.style.SUCCESS(f'Successfully processed {total} orders')
        )

Upgrade Guide

# Step 1: Check compatibility
python -Wa manage.py test

# Step 2: Update requirements
pip install Django>=4.2,<5.0

# Step 3: Run migrations
python manage.py migrate

# Step 4: Update deprecated features
# - Replace USE_L10N (removed)
# - Update STORAGES setting
# - Review async code patterns

Conclusion

Django 4.2 LTS provides stability and modern features for production applications. Three years of support makes it ideal for enterprise deployments requiring long-term maintenance.

Planning Django 4.2 upgrade? Contact ZIRA Software for migration assistance.