Data Transfer Objects with Django Ninja

Data Transfer Objects (DTOs) is an object-oriented design pattern for encapsulating data in a layer that handles input / output concerns such as serialization and validation.

In Django Ninja, DTOs can be implemented as pydantic models, which Ninja uses via type hinting to perform automatic serialization, deserialization, and validation. A service layer then enables these DTOs to be read from and written to the backend.

The example exposes a CRUD API for a simple model called Widget, showing how DTOs, services, and views can be composed.

Example request bodies are provided:

• create-widget.json - POST to /api/widget with this request body to create your first widget
• update-widget.json - PUT to /api/widget/{id} with this request body to update a widget
• bad-create-widget.json - POST to /api/widget with this request body to receive a validation error

Example validation error output

Here's the validation error detail you'll receive when POSTing bad-create-widget.json to /api/widget:

{
    "detail": [
        {
            "type": "missing",
            "loc": [
                "body",
                "input",
                "name"
            ],
            "msg": "Field required"
        },
        {
            "type": "string_type",
            "loc": [
                "body",
                "input",
                "description"
            ],
            "msg": "Input should be a valid string"
        }
    ]
}

Using the client

1. Install requirements:

   pip install -r client-requirements.txt
   

2. Acquire an authentication token using Django admin.
3. Copy dotenv.template to .env and replace the example token with your real token
4. Run the client:

   python client.py
   

The client exercises all endpoints and shows status codes and outputs for each one.