Flask Integration

Dependency injection for Flask is available in the wireup.integration.flask module.

• Automatic Dependency Management

  ---

  Inject dependencies in routes and automatically manage container lifecycle.

• Shared business logic

  ---

  Wireup is framework-agnostic. Share the service layer between web applications and other interfaces, such as a CLI.

Initialize the integration

First, create a sync container with your dependencies:

from flask import Flask
from wireup import Inject, Injected, injectable

app = Flask(__name__)
app.config["FOO"] = "bar"

container = wireup.create_sync_container(
    injectables=[services],
    config={
        **app.config,  # Optionally expose flask configuration to the container
        "API_KEY": "secret",
    },
)

Then initialize the integration by calling wireup.integration.flask.setup after adding all views and configuration:

# Initialize the integration.
# Must be called after views and configuration have been added.
wireup.integration.flask.setup(container, app)

Inject in Flask Views

To inject dependencies, add the type to the view's signature and annotate with Injected[T] or Annotated[T, Inject(...)].

Flask View

@app.get("/random")
def get_random(random: Injected[RandomService]):
    return {"lucky_number": random.get_random()}


@app.get("/env")
def get_environment(
    is_debug: Annotated[bool, Inject(config="DEBUG")],
    foo: Annotated[str, Inject(config="FOO")],
):
    return {"debug": is_debug, "foo": foo}

Accessing the Container

To access the Wireup container directly, use the following functions:

from wireup.integration.flask import get_app_container, get_request_container

# Get application-wide container
app_container = get_app_container(app)

# Get request-scoped container
request_container = get_request_container()

Testing

For general testing tips with Wireup refer to the test docs. With the Flask integration, you can override dependencies in the container as follows.

test_thing.py

from wireup.integration.flask import get_app_container


def test_override():
    class DummyGreeter(GreeterService):
        def greet(self, name: str) -> str:
            return f"Hi, {name}"

    with get_app_container(app).override.injectable(
        GreeterService,
        new=DummyGreeter(),
    ):
        res = self.client.get("/greet?name=Test")

See Flask integration tests for more examples.

API Reference

• flask_integration