__init__.py

__init__.py#

What is __init__.py?#

__init__.py marks a directory as a Python package and allows Django to import and manage project components correctly.

Short definition:

__init__.py tells Python: “This folder is a Python package.”

Without it, Python would not treat the folder as importable code.

Where you see __init__.py in your project#

In your Django project, it appears in many places:

mysite/
├── __init__.py
├── asgi.py
├── settings.py
├── urls.py
├── wsgi.py

myapp/
├── __init__.py
├── admin.py
├── apps.py
├── models.py
├── views.py

migrations/
├── __init__.py

Each one has a slightly different role, but the core idea is the same.

Why __init__.py exists#

Python organizes code using packages.

Example:

import myapp.models
Python can only do this if:

  • ✔ myapp/ is a package

  • ✔ __init__.py exists inside it

What happens if __init__.py is missing?#

Older Python (≤3.2)

Folder is NOT a package

Imports fail

Modern Python (3.3+)

✔ Namespace packages exist

But Django still expects __init__.py

Django best practice: always keep it

What is inside __init__.py?#

Most of the time:

# empty

And that is 100% correct

Empty does NOT mean useless.

What does Django use __init__.py for?#

1️⃣ Package recognition

Django imports apps, settings, models, migrations — all via packages.

2️⃣ App loading

Django uses INSTALLED_APPS:

INSTALLED_APPS = [
    'myapp',
]

Django internally imports:

import myapp

➡️ __init__.py enables this.

3️⃣ Migrations discovery

Django scans:

myapp.migrations

Without __init__.py, migrations break.

Advanced usage (OPTIONAL, but powerful)#

You can put code in __init__.py, but you must be careful.

Example: shortcut imports

# myapp/__init__.py
from .models import Post

Now you can do:

from myapp import Post

Instead of:

from myapp.models import Post

Example: default app config (older Django)

default_app_config = 'myapp.apps.MyappConfig'

Mostly obsolete in modern Django, but still exists in legacy code.

What you should NOT do

Heavy logic

Database queries

API calls

Side effects

Why?

Because __init__.py runs as soon as the package is imported.

__init__.py in migrations folder

migrations/__init__.py
Purpose:

  • Marks migrations as a package

  • Allows Django to auto-discover migration files

You never touch this file.

Simple mental model

Think of __init__.py as:

“Package start file”

Just like:

  • main() in C

  • index.js in Node

  • __init__.py in Python packages

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