fix(python,asyncio): multipart form data serialization

[roryschadler]

This PR tackles a few serialization issues in the Python generator templates: serialization of dictionaries and integers in multipart/form-data requests.

I generated a library=asyncio client using latest master and modules/openapi-generator/src/test/resources/3_0/form-multipart-binary-array.yaml. The /multipart-mixed call fails with TypeError: Can not serialize value type: <class 'dict'>.

#18140 resolved this for library=urllib clients, but not for library=asyncio clients. Because tornado clients are deprecated, I didn't try to reproduce the bug there.

With that client created and installed, this snippet demonstrates the dict issues on master, and the fix here:

import asyncio
from example_asyncio_client.api_client import ApiClient as AsyncioApiClient
from example_asyncio_client.models.multipart_mixed_request_marker import (
    MultipartMixedRequestMarker as AsyncioMultipartMixedRequestMarker,
)
from example_asyncio_client.models.multipart_mixed_status import (
    MultipartMixedStatus as AsyncioMultipartMixedStatus,
)
from example_asyncio_client.configuration import Configuration as AsyncioConfiguration
from example_asyncio_client.api.multipart_api import MultipartApi as AsyncioMultipartApi


asyncio_configuration = AsyncioConfiguration(host="http://localhost:8008")


async def asyncio_main():
    async with AsyncioApiClient(asyncio_configuration) as asyncio_api_client:
        asyncio_api_instance = AsyncioMultipartApi(asyncio_api_client)
        marker = AsyncioMultipartMixedRequestMarker(name="Test")
        with open("hello-world.txt", "rb") as f:
            file1 = f.read()

        try:
            await asyncio_api_instance.multipart_mixed(
                status=AsyncioMultipartMixedStatus.ALLOWED,
                file=file1,
                marker=marker,
            )
        except TypeError as e:
            print(f"asyncio.multipart_mixed: {type(e).__name__}: {e}")


if __name__ == "__main__":
    asyncio.run(asyncio_main())

The other issue is serializing integers, which is also broken for library=asyncio clients. If a spec lists a multipart/form-data field as a number, then it needs to be stringified before being written to the form body. aiohttp has stated they won't do this for the user: aio-libs/aiohttp#920. urllib3 handles this for the user here: https://github.com/urllib3/urllib3/blob/9316764e90aea8d193cd8f03b0caccdf02af3ba0/src/urllib3/filepost.py#L75-L76

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[roryschadler]

cc @cbornet @tomplus @krjakbrjak @fa0311 @multani

[roryschadler]

@wing328 (or whoever is driving the review of this PR) I have another contribution to propose, which handles (filename, filedata) tuples for file parameters. Would it make more sense to split this PR into two: (1) for the dictionary/integer serialization, and (2) for the multiple file parameter support? edit: I did: #19329

[roryschadler]

@wing328 following up - are you the right person to review this?

[roryschadler]

@cbornet @tomplus @krjakbrjak @fa0311 @multani I'd really appreciate your review, thank you!

[multani]

@roryschadler sorry for the delay ; would you be able to extend the test suite to show the bug and your change fixes it?

[roryschadler]

No worries @multani! Happy to. Just to confirm, is that a manually-written test added to https://github.com/OpenAPITools/openapi-generator/tree/0f294a51297d788630c96a146a9a48d1dae3e3e5/samples/openapi3/client/petstore/python/tests, or do you mean a different test suite?

[multani]

Yes, this folder would be a good place.

The test file you already updated should contain some serialization tests already, maybe it could be a good place to extend with a regression test for your fix!

[roryschadler]

@multani added. The first test: commit is the additional endpoint, the second is the regression test. Note that I removed the other changed test you mentioned in the rebase, as it was included in my previous PR (#19329)

[multani]

@roryschadler thanks for the tests, I will take a look.

In the meantime, can you regenerate the sample files using the commands in the first message of the PR and commit the result? It should fix the unsuccessful check. Thanks!

[multani]

I did a basic check if the fix was working and it seems so.

I'm really not familiar with the multipart code, @wing328 if you want to take another look, that would be great :)

[multani]

Can you adjust the aiohttp test setup? It took me some time to figure out why it wasn't working on my machine :)

The same fix should probably be done for pydantic-v1-aiohttp.

[multani]

Looks good to me, thanks for the fix(es) @roryschadler !

@wing328 can you take a look as well?

[roryschadler]

@wing328 bumping this up in your inbox. Looking forward to your review, thank you!

[roryschadler]

@wing328 Checking in on this. Is there anything I can do to support your review?

[wing328]

thanks for the PR, which has been merged

sorry for the delay.

[roryschadler]

Thank you, @wing328!