django-annotate

🧾 django-annotate

Annotate Django model files with schema information (fields, indexes, and foreign keys), inspired by the annotaterb project for Rails.

✨ Features

• Adds # == Schema Information blocks above each model class
• Supports:
  • Field types
  • Indexes (including unique constraints)
  • Foreign key relationships
• Works on monolithic or multi-file model setups
• CLI support via Django's manage.py

🗄️ Database Support

Currently, django-annotate only supports PostgreSQL databases. This is because it uses PostgreSQL-specific system tables (pg_*) to introspect the database schema. Support for other databases (MySQL, SQLite) is planned for future releases.

Requirements

• PostgreSQL database
• Django project configured to use PostgreSQL as the database backend
• Appropriate database permissions to query system tables
• Standard Django ORM models (inheriting from django.db.models.Model)

If you're using a different database backend, you'll need to either:

• Switch to PostgreSQL
• Wait for support for your database to be added
• Contribute support for your database backend

📦 Installation

pip install django-annotate
# or if using Poetry:
poetry add django-annotate

⚙️ Setup

No configuration required — just install and run. If you want to run it via Django's CLI, ensure django_annotate is on your Python path (you don't need to add it to INSTALLED_APPS unless you want auto-discovery inside Django).

Then run:

python manage.py annotate_models

This will annotate models in all installed apps (excluding any apps listed in ignore_apps in your configuration).

To annotate a specific app:

python manage.py annotate_models --app=myapp

🔄 Auto-Annotation After Migrations

By default, model annotation runs automatically after every migration in development environments. This helps keep your model files up-to-date with your database schema.

Auto-annotation is disabled by default in production environments when DEBUG = False (typical in production).

To control auto-annotation behavior, you can configure the following settings in your .django_annotate.yml file:

# Auto-annotation settings
skip_on_migrate: false     # Set to true to disable auto-annotation after migrations
force: false               # Set to true to force annotation even if the file hasn't changed
frozen: false              # Set to true to prevent any automatic annotation

🧪 Example Output

# == Schema Information
#
# Table name: organizations
#
#  id         :bigint           not null, primary key
#  name       :varchar(255)     not null
#  created_at :timestamp        not null
#
# Indexes
#
#  organizations_pkey  (id)
#
# Foreign Keys
#
#  (none)
#

class Organization(models.Model):
    name = models.CharField(max_length=255)
    created_at = models.DateTimeField(auto_now_add=True)


# == Schema Information
#
# Table name: users
#
#  id              :bigint           not null, primary key
#  email           :varchar(254)     not null
#  full_name       :varchar(255)     not null
#  organization_id :bigint           not null
#  created_at      :timestamp        not null
#
# Indexes
#
#  users_email_key            (email) UNIQUE
#  users_organization_id_idx  (organization_id)
#
# Foreign Keys
#
#  organization_id => organizations.id
#

class User(models.Model):
    organization = models.ForeignKey(Organization, on_delete=models.CASCADE)
    email = models.EmailField(unique=True)
    full_name = models.CharField(max_length=255)
    created_at = models.DateTimeField(auto_now_add=True)


# == Schema Information
#
# Table name: profiles
#
#  id      :bigint           not null, primary key
#  user_id :bigint           not null
#  bio     :text
#
# Indexes
#
#  profiles_user_id_key  (user_id) UNIQUE
#
# Foreign Keys
#
#  user_id => users.id
#

class Profile(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE)
    bio = models.TextField(blank=True)


# == Schema Information
#
# Table name: projects
#
#  id         :bigint           not null, primary key
#  name       :varchar(255)     not null
#  created_at :timestamp        not null
#
# Indexes
#
#  projects_pkey  (id)
#
# Foreign Keys
#
#  (none)
#

class Project(models.Model):
    name = models.CharField(max_length=255)
    created_at = models.DateTimeField(auto_now_add=True)
    members = models.ManyToManyField(User, related_name="projects")

📜 License

MIT © 2025 Chris Davis

⚙️ Configuration

You can configure django-annotate by creating a .django_annotate.yml file in your project root. Here's a comprehensive list of all available configuration options:

# Position settings
position: before  # before or after the model class

# Schema information settings
show_indexes: true
show_foreign_keys: true
with_column_comments: true
include_version: false
timestamp: false

# Exclusion settings
ignore_models: []  # list of model names to ignore
ignore_apps: []    # list of app labels to ignore
ignore_columns: []

# Auto-annotation settings
skip_on_migrate: false
force: false
frozen: false

Quick Start

For most projects, you can start with a minimal configuration file. For example, to control auto-annotation behavior:

# Auto-annotation settings
skip_on_migrate: false  # Set to true to disable auto-annotation after migrations
force: false  # Set to true to force annotation even if the file hasn't changed
frozen: false  # Set to true to prevent any automatic annotation

All other settings will use sensible defaults. You can add more settings as needed.

Production Safety

By default, django-annotate will not run in production environments. This is enforced by:

• Not running when DEBUG = False (typical in production)
• Respecting the frozen setting in your configuration

To ensure safety in production, add this to your .django_annotate.yml:

# Auto-annotation settings
frozen: true  # Prevents any automatic annotation

The recommended workflow is:

• Run migrations and annotations locally
• Commit the annotated files to version control
• Deploy the committed files to production