refactor-django_skill

Overview

This skill refactors Django and Python code to improve maintainability, readability, and alignment with modern best practices. It converts fat views, inefficient ORM usage, and outdated patterns into clean, testable code that leverages Python 3.12+ and Django 5+ features. The focus is practical: safer types, explicit errors, and service-layer design that makes code easier to change and review.

How this skill works

I analyze your code to identify anti-patterns such as mutable defaults, bare excepts, N+1 queries, and business logic in views. I then transform the code into modular units: services/use-cases, typed functions and data classes, lean views, and optimized ORM queries (select_related, prefetch_related, GeneratedField where appropriate). I also apply Python 3.12 features (type parameter syntax, @override) and Django 5+ patterns (GeneratedField, db_default, async views) while keeping behavior equivalent and tests passing.

When to use it

• When views contain business logic, long functions, or repeated code that should be extracted to services.
• When you observe N+1 query symptoms or slow list/detail endpoints driven by ORM inefficiencies.
• When code uses outdated Python/Django idioms that hinder maintainability or type safety.
• When tests are hard to write because functions are large or tightly coupled to frameworks.
• When you want migration-safe model improvements (GeneratedField, db_default) for correctness or performance.

Best practices

• Make views thin: delegate validation and side effects to service classes or functions.
• Prefer explicit exception handling and specific error types over bare except blocks.
• Annotate public APIs and domain objects with robust type hints and use dataclasses for value objects.
• Use select_related/prefetch_related and custom QuerySets to avoid N+1 queries.
• Apply Python 3.12 features conservatively: type parameter syntax, @override, and inlined comprehensions where they improve clarity.
• Follow PEP 8 and automated formatting/linters (black, ruff, isort) to keep style consistent.

Example use cases

• Refactor a Django REST endpoint that performs validation, DB writes, and external calls into a thin view + OrderService with clear unit tests.
• Fix an orders list API that triggers N+1 queries by adding select_related and a custom QuerySet with prefetch optimizations.
• Migrate a computed attribute into a GeneratedField for database-side consistency and query efficiency.
• Convert synchronous views to async where I/O-bound work exists and use async ORM patterns safely.
• Replace mutable default args and broad exception handlers with explicit defaults and targeted exception types.