• Fetch related ForeignKey objects in the same query.

entries = Entry.objects.select_related('author').all()

• Fetch related ManyToManyField objects in a separate efficient query.

entries = Entry.objects.prefetch_related('tags').all()

• Load only specific model fields.

entries = Entry.objects.only('headline')

• Defer loading of specific model fields.

entries = Entry.objects.defer('body_text')

• Execute raw, unmanaged SQL.

authors = Author.objects.raw('SELECT * FROM myapp_author')

• Get results as a list of tuples.

Entry.objects.values_list('headline', 'pub_date')

XV. Transactions

• Import the transaction module.

from django.db import transaction

• Run a block of code within a database transaction.

with transaction.atomic():
    # All database operations here are either committed together or rolled back.
    author.save()
    entry.save()

XVI. Managers & Model Methods

• Create a custom Manager for common queries.

class PublishedEntryManager(models.Manager):
    def get_queryset(self):
        return super().get_queryset().filter(status='published')

• Add a custom method to a QuerySet via its Manager.

Entry.objects.get_queryset().by_author("John Doe")

• Add a custom method to a model for object-specific logic.

class Entry(models.Model):
    #...
    def is_recent(self):
        return self.pub_date > timezone.now() - timedelta(days=1)

#Python #Django #ORM #Database #Backend

━━━━━━━━━━━━━━━
By: @DataScience4 ✨

❤️ Architecture Patterns — an informative repository on backend architecture in Python!

Here, they excellently demonstrate how to properly separate application logic, work with complex architecture, build a scalable backend, and maintain a codebase in an adequate state as the project grows. Instead of dry theory, the authors gradually build a full-fledged application and show how the architecture evolves as the project grows.

I'll leave a link: https://github.com/cosmicpython/book

#Python #Backend #Architecture #Coding #DevCommunity #OpenSource

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Cheat sheet on Python Frameworks:

Django: A full-featured web framework with built-in ORM, admin panel, and security features.

Flask: A lightweight microframework with a minimal set of features and high flexibility.

ORM & Admin: Built-in to Django, but need to be connected separately in Flask.

Security: Django has built-in security mechanisms, while in Flask, they need to be configured manually.

Testing: Django offers built-in testing tools, while Flask relies on third-party libraries.

Use Cases: Django is suitable for large and complex projects, while Flask is better for small applications, APIs, and prototypes.

#Python #WebDev #Django #Flask #Backend #Programming

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🚀 Django 6.1: Loading related data on demand, cascading deletion handled by the database, and a new email configuration.

The release was made on August 5th. Three major changes:

1. New Field Loading Modes 📂

FETCH_PEERS retrieves data for related objects from the same QuerySet when accessing an un-loaded field. This helps combat the N+1 problem:

from django.db import models

books = Book.objects.fetch_mode(models.FETCH_PEERS)

for book in books:
    print(book.author.name)

In this example, Django executes two queries: one for the books and one for their authors.

The FETCH_RAISE mode raises an exception instead of performing an implicit query – useful for detecting unexpected database accesses.

2. Deletion at the Database Level 🗑

For ForeignKey.on_delete, the options DB_CASCADE, DB_SET_NULL, and DB_SET_DEFAULT are now available. The logic is handled directly by the database using SQL ON DELETE.

Note: DB_CASCADE does not trigger pre_delete and post_delete signals.

3. Multiple Email Backends 📧

The MAILERS configuration allows you to define different connections using a dictionary, and you can select the desired connection when sending emails using the using parameter.

Before upgrading, check your database versions: you need PostgreSQL 15+, MySQL 8.4+, MariaDB 10.11+, or SQLite 3.37+.

🔗 https://www.djangoproject.com/weblog/2026/aug/05/django-61-released/

#Django #Python #WebDevelopment #Django61 #Backend #TechNews

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