Sanic example

This example shows how to use Dependency Injector with Sanic.

The example application is a REST API that searches for funny GIFs on the Giphy.

The source code is available on the Github.

Application structure

Application has next structure:

./
├── giphynavigator/
│   ├── __init__.py
│   ├── __main__.py
│   ├── application.py
│   ├── containers.py
│   ├── giphy.py
│   ├── handlers.py
│   ├── services.py
│   └── tests.py
├── config.yml
└── requirements.txt

Container

Declarative container is defined in giphynavigator/containers.py:

"""Containers module."""

from dependency_injector import containers, providers

from . import giphy, services


class Container(containers.DeclarativeContainer):

    config = providers.Configuration()

    giphy_client = providers.Factory(
        giphy.GiphyClient,
        api_key=config.giphy.api_key,
        timeout=config.giphy.request_timeout,
    )

    search_service = providers.Factory(
        services.SearchService,
        giphy_client=giphy_client,
    )

Handlers

Handler has dependencies on search service and some config options. The dependencies are injected using Wiring feature.

Listing of giphynavigator/handlers.py:

"""Handlers module."""

from sanic.request import Request
from sanic.response import HTTPResponse, json
from dependency_injector.wiring import Provide

from .services import SearchService
from .containers import Container


async def index(
        request: Request,
        search_service: SearchService = Provide[Container.search_service],
        default_query: str = Provide[Container.config.default.query],
        default_limit: int = Provide[Container.config.default.limit.as_int()],
) -> HTTPResponse:
    query = request.args.get('query', default_query)
    limit = int(request.args.get('limit', default_limit))

    gifs = await search_service.search(query, limit)

    return json(
        {
            'query': query,
            'limit': limit,
            'gifs': gifs,
        },
    )

Application factory

Application factory creates container, wires it with the handlers module, creates Sanic app and setup routes.

Listing of giphynavigator/application.py:

"""Application module."""

from sanic import Sanic

from .containers import Container
from . import handlers


def create_app() -> Sanic:
    """Create and return Sanic application."""
    container = Container()
    container.config.from_yaml('config.yml')
    container.config.giphy.api_key.from_env('GIPHY_API_KEY')
    container.wire(modules=[handlers])

    app = Sanic('Giphy Navigator')
    app.container = container
    app.add_route(handlers.index, '/')
    return app

Tests

Tests use Provider overriding feature to replace giphy client with a mock giphynavigator/tests.py:

"""Tests module."""

from unittest import mock

import pytest

from giphynavigator.application import create_app
from giphynavigator.giphy import GiphyClient


@pytest.fixture
def app():
    app = create_app()
    yield app
    app.container.unwire()


async def test_index(app):
    giphy_client_mock = mock.AsyncMock(spec=GiphyClient)
    giphy_client_mock.search.return_value = {
        'data': [
            {'url': 'https://giphy.com/gif1.gif'},
            {'url': 'https://giphy.com/gif2.gif'},
        ],
    }

    with app.container.giphy_client.override(giphy_client_mock):
        _, response = await app.asgi_client.get(
            '/',
            params={
                'query': 'test',
                'limit': 10,
            },
        )

    assert response.status == 200
    data = response.json()
    assert data == {
        'query': 'test',
        'limit': 10,
        'gifs': [
            {'url': 'https://giphy.com/gif1.gif'},
            {'url': 'https://giphy.com/gif2.gif'},
        ],
    }


async def test_index_no_data(app):
    giphy_client_mock = mock.AsyncMock(spec=GiphyClient)
    giphy_client_mock.search.return_value = {
        'data': [],
    }

    with app.container.giphy_client.override(giphy_client_mock):
        _, response = await app.asgi_client.get('/')

    assert response.status == 200
    data = response.json()
    assert data['gifs'] == []


async def test_index_default_params(app):
    giphy_client_mock = mock.AsyncMock(spec=GiphyClient)
    giphy_client_mock.search.return_value = {
        'data': [],
    }

    with app.container.giphy_client.override(giphy_client_mock):
        _, response = await app.asgi_client.get('/')

    assert response.status == 200
    data = response.json()
    assert data['query'] == app.container.config.default.query()
    assert data['limit'] == app.container.config.default.limit()

Sources

Explore the sources on the Github.