Documentation is asking to type with fastapi.datastructures.UploadFile, but starlette.datastructures.UploadFile is actually used, causing a type error #9705

gabrieldemarmiesse · 2023-06-20T07:01:30Z

gabrieldemarmiesse
Jun 20, 2023

First Check

I added a very descriptive title here.
I used the GitHub search to find a similar question and didn't find it.
I searched the FastAPI documentation, with the integrated search.
I already searched in Google "How to X in FastAPI" and didn't find any information.
I already read and followed all the tutorial in the docs and didn't find an answer.
I already checked if it is not related to FastAPI but to Pydantic.
I already checked if it is not related to FastAPI but to Swagger UI.
I already checked if it is not related to FastAPI but to ReDoc.

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I commit to help with one of those options 👆

Example Code

from fastapi import FastAPI, UploadFile
from fastapi.testclient import TestClient
from io import BytesIO

app = FastAPI()


@app.post("/")
def send_file(some_file: UploadFile) -> str:
    return str(type(some_file))

client = TestClient(app)


response = client.post("/", files={'some_file': BytesIO(b"Hello world")})
print(response.text)

Description

Just run the script, the type of some_file is starlette.datastructures.UploadFile instead of fastapi.datastructures.UploadFile. This is causing type checkers to flag this as an error.

This example come straight from the documentation (the example with UploadFile and the one showing how to do unit testing. So nothing exotic here.

Operating System

Linux

Operating System Details

I work in Docker. But I'm pretty sure this type bug is unrelated to my operating system.

FastAPI Version

0.97.0

Python Version

Python 3.10.10

Additional Context

Using isinstance is also causing an issue:

@app.post("/")
def send_file(some_file: UploadFile) -> str:
    assert isinstance(some_file, UploadFile)
    return str(type(some_file))

fails.

It is likely unrelated as those examples confirms the type is wrong, but the type checker I usually use is typeguard.

It fails on all the endpoints using FileUpload with typeguard.TypeCheckError: argument "file" (starlette.datastructures.UploadFile) is not an instance of fastapi.datastructures.UploadFile

Kludex · 2023-06-20T08:58:04Z

Kludex
Jun 20, 2023
Collaborator

What type checker? What version of the type checker? What command?

1 reply

gabrieldemarmiesse Jun 20, 2023
Author

The type checker is typeguard, as mentionned in the issue.
typeguard==4.0.0.
Here is a self contained script:

from fastapi import FastAPI, UploadFile
from fastapi.testclient import TestClient
from io import BytesIO
from typeguard import typechecked

app = FastAPI()

@app.post("/")
@typechecked
def send_file(some_file: UploadFile) -> str:
    assert isinstance(some_file, UploadFile)
    return str(type(some_file))

client = TestClient(app)


response = client.post("/", files={'some_file': BytesIO(b"Hello world")})
print(response.text)

The error:

/opt/conda/bin/python /projects/work/scube/trying_stuff.py 
Traceback (most recent call last):
  File "/projects/work/scube/trying_stuff.py", line 17, in <module>
    response = client.post("/", files={'some_file': BytesIO(b"Hello world")})
  File "/opt/conda/lib/python3.10/site-packages/starlette/testclient.py", line 590, in post
    return super().post(
  File "/opt/conda/lib/python3.10/site-packages/httpx/_client.py", line 1132, in post
    return self.request(
  File "/opt/conda/lib/python3.10/site-packages/starlette/testclient.py", line 465, in request
    return super().request(
  File "/opt/conda/lib/python3.10/site-packages/httpx/_client.py", line 814, in request
    return self.send(request, auth=auth, follow_redirects=follow_redirects)
  File "/opt/conda/lib/python3.10/site-packages/httpx/_client.py", line 901, in send
    response = self._send_handling_auth(
  File "/opt/conda/lib/python3.10/site-packages/httpx/_client.py", line 929, in _send_handling_auth
    response = self._send_handling_redirects(
  File "/opt/conda/lib/python3.10/site-packages/httpx/_client.py", line 966, in _send_handling_redirects
    response = self._send_single_request(request)
  File "/opt/conda/lib/python3.10/site-packages/httpx/_client.py", line 1002, in _send_single_request
    response = transport.handle_request(request)
  File "/opt/conda/lib/python3.10/site-packages/starlette/testclient.py", line 342, in handle_request
    raise exc
  File "/opt/conda/lib/python3.10/site-packages/starlette/testclient.py", line 339, in handle_request
    portal.call(self.app, scope, receive, send)
  File "/opt/conda/lib/python3.10/site-packages/anyio/from_thread.py", line 283, in call
    return cast(T_Retval, self.start_task_soon(func, *args).result())
  File "/opt/conda/lib/python3.10/concurrent/futures/_base.py", line 458, in result
    return self.__get_result()
  File "/opt/conda/lib/python3.10/concurrent/futures/_base.py", line 403, in __get_result
    raise self._exception
  File "/opt/conda/lib/python3.10/site-packages/anyio/from_thread.py", line 219, in _call_func
    retval = await retval
  File "/opt/conda/lib/python3.10/site-packages/fastapi/applications.py", line 282, in __call__
    await super().__call__(scope, receive, send)
  File "/opt/conda/lib/python3.10/site-packages/starlette/applications.py", line 122, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/opt/conda/lib/python3.10/site-packages/starlette/middleware/errors.py", line 184, in __call__
    raise exc
  File "/opt/conda/lib/python3.10/site-packages/starlette/middleware/errors.py", line 162, in __call__
    await self.app(scope, receive, _send)
  File "/opt/conda/lib/python3.10/site-packages/starlette/middleware/exceptions.py", line 79, in __call__
    raise exc
  File "/opt/conda/lib/python3.10/site-packages/starlette/middleware/exceptions.py", line 68, in __call__
    await self.app(scope, receive, sender)
  File "/opt/conda/lib/python3.10/site-packages/fastapi/middleware/asyncexitstack.py", line 20, in __call__
    raise e
  File "/opt/conda/lib/python3.10/site-packages/fastapi/middleware/asyncexitstack.py", line 17, in __call__
    await self.app(scope, receive, send)
  File "/opt/conda/lib/python3.10/site-packages/starlette/routing.py", line 718, in __call__
    await route.handle(scope, receive, send)
  File "/opt/conda/lib/python3.10/site-packages/starlette/routing.py", line 276, in handle
    await self.app(scope, receive, send)
  File "/opt/conda/lib/python3.10/site-packages/starlette/routing.py", line 66, in app
    response = await func(request)
  File "/opt/conda/lib/python3.10/site-packages/fastapi/routing.py", line 241, in app
    raw_response = await run_endpoint_function(
  File "/opt/conda/lib/python3.10/site-packages/fastapi/routing.py", line 169, in run_endpoint_function
    return await run_in_threadpool(dependant.call, **values)
  File "/opt/conda/lib/python3.10/site-packages/starlette/concurrency.py", line 41, in run_in_threadpool
    return await anyio.to_thread.run_sync(func, *args)
  File "/opt/conda/lib/python3.10/site-packages/anyio/to_thread.py", line 31, in run_sync
    return await get_asynclib().run_sync_in_worker_thread(
  File "/opt/conda/lib/python3.10/site-packages/anyio/_backends/_asyncio.py", line 937, in run_sync_in_worker_thread
    return await future
  File "/opt/conda/lib/python3.10/site-packages/anyio/_backends/_asyncio.py", line 867, in run
    result = context.run(func, *args)
  File "/projects/work/scube/trying_stuff.py", line 10, in send_file
    def send_file(some_file: UploadFile) -> str:
  File "/opt/conda/lib/python3.10/site-packages/typeguard/_functions.py", line 135, in check_argument_types
    check_type_internal(value, annotation, memo)
  File "/opt/conda/lib/python3.10/site-packages/typeguard/_checkers.py", line 761, in check_type_internal
    raise TypeCheckError(f"is not an instance of {qualified_name(origin_type)}")
typeguard.TypeCheckError: argument "some_file" (starlette.datastructures.UploadFile) is not an instance of fastapi.datastructures.UploadFile

Process finished with exit code 1

gabrieldemarmiesse · 2023-07-16T13:47:48Z

gabrieldemarmiesse Jul 16, 2023
Author

@black-pwq it seems unrelated to my original bug report, you'll have more success opening a new discussion with your issue

black-pwq · 2023-07-16T16:27:37Z

black-pwq Jul 16, 2023

Well, I deploy it on the server for long time running and simply restarting the service solves the problem.

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Documentation is asking to type with fastapi.datastructures.UploadFile, but starlette.datastructures.UploadFile is actually used, causing a type error #9705

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gabrieldemarmiesse Jun 20, 2023

First Check

Commit to Help

Example Code

Description

Operating System

Operating System Details

FastAPI Version

Python Version

Additional Context

Replies: 2 comments · 3 replies

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Kludex Jun 20, 2023 Collaborator

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gabrieldemarmiesse
Jun 20, 2023

Replies: 2 comments 3 replies

Kludex
Jun 20, 2023
Collaborator

gabrieldemarmiesse Jun 20, 2023
Author

gabrieldemarmiesse Jul 16, 2023
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