FastAPI Troubleshooting

Common issues and fixes for Wireup's FastAPI integration.

Injection is not set up correctly

Symptom:

• You get an error saying injection is not set up correctly when hitting an endpoint.

Fix:

1. Make sure wireup.integration.fastapi.setup(container, app) is called.
2. Make sure routes use Injected[...] or @inject where expected.

container = wireup.create_async_container(
    injectables=[services, wireup.integration.fastapi]
)
app = FastAPI()

wireup.integration.fastapi.setup(container, app)

Tests fail but app works

Symptom:

• Injection or startup behavior fails in tests.

Fix:

Use TestClient as a context manager so FastAPI lifespan runs.

def test_endpoint(app: FastAPI):
    with TestClient(app) as client:
        res = client.get("/")
        assert res.status_code == 200

get_request_container() is unavailable in middleware/helpers

Symptom:

• get_request_container() raises WireupError in middleware or request-time decorators/helpers.

Fix:

1. Call setup with middleware_mode=True.
2. Make sure Wireup middleware is outermost (middleware ordering matters).

wireup.integration.fastapi.setup(container, app, middleware_mode=True)

get_request_container() is unavailable in WebSocket handlers

Symptom:

• get_request_container() raises inside WebSocket routes.

Why:

• Middleware-backed request containers in FastAPI are HTTP-only.

Fix:

• Prefer Injected[...] in websocket handlers/services.
• Use get_app_container(app) outside request scope if needed.

Middleware added after setup(...)

Symptom:

• Request-container behavior in middleware is inconsistent.

Fix:

• Add middleware before calling setup(...).
• If middleware needs request-scoped DI, also enable middleware_mode=True.