Fix error in fastapi example

[realimpat]

There's an error in the api.py file in the fastapi.

Here's the error:

 in Onboarding Flow' - Created task run 'Enroll [email protected] in Onboarding Flow' for task 'enroll_in_onboarding_flow'
api-1        | 22:30:45.656 | INFO    | prefect.tasks - Created task run 'populate_workspace'. View it in the UI at 'http://prefect:4200/runs/task-run/1a76e005-c48d-45d3-84a8-a6e23c4de347'
api-1        | Exception in ASGI application
api-1        | Traceback (most recent call last):
api-1        |   File "/usr/local/lib/python3.12/site-packages/uvicorn/protocols/http/h11_impl.py", line 412, in run_asgi
api-1        |     result = await app(  # type: ignore[func-returns-value]
api-1        |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
api-1        |   File "/usr/local/lib/python3.12/site-packages/uvicorn/middleware/proxy_headers.py", line 84, in __call__
api-1        |     return await self.app(scope, receive, send)
api-1        |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
api-1        |   File "/usr/local/lib/python3.12/site-packages/fastapi/applications.py", line 1054, in __call__
api-1        |     await super().__call__(scope, receive, send)
api-1        |   File "/usr/local/lib/python3.12/site-packages/starlette/applications.py", line 123, in __call__
api-1        |     await self.middleware_stack(scope, receive, send)
api-1        |   File "/usr/local/lib/python3.12/site-packages/starlette/middleware/errors.py", line 186, in __call__
api-1        |     raise exc
api-1        |   File "/usr/local/lib/python3.12/site-packages/starlette/middleware/errors.py", line 164, in __call__
api-1        |     await self.app(scope, receive, _send)
api-1        |   File "/usr/local/lib/python3.12/site-packages/starlette/middleware/exceptions.py", line 65, in __call__
api-1        |     await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send)
api-1        |   File "/usr/local/lib/python3.12/site-packages/starlette/_exception_handler.py", line 64, in wrapped_app
api-1        |     raise exc
api-1        |   File "/usr/local/lib/python3.12/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
api-1        |     await app(scope, receive, sender)
api-1        |   File "/usr/local/lib/python3.12/site-packages/starlette/routing.py", line 754, in __call__
api-1        |     await self.middleware_stack(scope, receive, send)
api-1        |   File "/usr/local/lib/python3.12/site-packages/starlette/routing.py", line 774, in app
api-1        |     await route.handle(scope, receive, send)
api-1        |   File "/usr/local/lib/python3.12/site-packages/starlette/routing.py", line 295, in handle
api-1        |     await self.app(scope, receive, send)
api-1        |   File "/usr/local/lib/python3.12/site-packages/starlette/routing.py", line 77, in app
api-1        |     await wrap_app_handling_exceptions(app, request)(scope, receive, send)
api-1        |   File "/usr/local/lib/python3.12/site-packages/starlette/_exception_handler.py", line 64, in wrapped_app
api-1        |     raise exc
api-1        |   File "/usr/local/lib/python3.12/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
api-1        |     await app(scope, receive, sender)
api-1        |   File "/usr/local/lib/python3.12/site-packages/starlette/routing.py", line 74, in app
api-1        |     response = await f(request)
api-1        |                ^^^^^^^^^^^^^^^^
api-1        |   File "/usr/local/lib/python3.12/site-packages/fastapi/routing.py", line 297, in app
api-1        |     raw_response = await run_endpoint_function(
api-1        |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
api-1        |   File "/usr/local/lib/python3.12/site-packages/fastapi/routing.py", line 210, in run_endpoint_function
api-1        |     return await dependant.call(**values)
api-1        |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
api-1        |   File "/app/fastapi_user_signups/api.py", line 21, in create_user
api-1        |     await asyncio.gather(
api-1        |           ^^^^^^^^^^^^^^^
api-1        |   File "/usr/local/lib/python3.12/asyncio/tasks.py", line 831, in gather
api-1        |     fut = ensure_future(arg, loop=loop)
api-1        |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
api-1        |   File "/usr/local/lib/python3.12/asyncio/tasks.py", line 689, in ensure_future
api-1        |     raise TypeError('An asyncio.Future, a coroutine or an awaitable '
api-1        | TypeError: 

Here's an explanation.

The error occurs because tasks.send_confirmation_email.delay() (and the other task delays) don't return coroutines that can be awaited.

In Prefect, the .delay() method is used to schedule a task for execution, but it's not meant to be awaited. You're trying to use asyncio.gather() with these non-awaitable task schedules.

Here's how to fix the code:

@app.post("/users", status_code=201)
async def create_user(new_user: NewUser) -> User:
    user = await models.create_user(new_user)

    # Don't await these - they're fire-and-forget tasks
    tasks.send_confirmation_email.delay(user)
    tasks.enroll_in_onboarding_flow.delay(user)
    tasks.populate_workspace.delay(user)

    return user

The key changes:

1. Removed the asyncio.gather() since it's not needed
2. Simply call .delay() on each task without awaiting them

This matches the intention described in the README:

These are fire-and-forget tasks that need to happen, but the request cycle doesn't need
to wait on them to complete.

The tasks are meant to be "fire-and-forget" - they should be queued up to run asynchronously without the API request waiting for them to complete.