Issue with MultiPartParser class

Checklist

• The bug is reproducible against the latest release and/or master.
• There are no similar issues or pull requests to fix it yet.

Describe the bug

MultiPartParser class fails to parse a request body produced by the client but not Postman (or similar).

To reproduce

from starlette.formparsers import MultiPartParser, FormParser
from starlette.datastructures import Headers
import asyncio


client_body = b'--xoxoxoxoxoxoxoxoxoxo_1600710720987\r\nContent-Disposition: form-data; name="fasta"; filename="sequences.fasta"\r\nContent-Type: multipart/form-data\r\n\r\n>P23A07_IgM-1047:H:Q10C92:17/22:NID2093\nCAGGTTTCAGTAG\n--xoxoxoxoxoxoxoxoxoxo_1600710720987\r\nContent-Disposition: form-data; name="attributes"; filename="attributes.tsv"\r\nContent-Type: multipart/form-data\r\n\r\n"Campaign ID"\t"Plate Set ID"\t"No"\n\r\n--xoxoxoxoxoxoxoxoxoxo_1600710720987--\r\n'
client_headers = Headers({'accept-encoding': 'gzip,deflate', 'content-length': '39940', 'content-type': 'multipart/form-data; boundary=xoxoxoxoxoxoxoxoxoxo_1600710720987', 'host': '10.0.5.13:80', 'connection': 'Keep-Alive', 'user-agent': 'KNIME Uploader'})

postman_body = b'----------------------------850116600781883365617864\r\nContent-Disposition: form-data; name="attributes"; filename="test-attribute_5.tsv"\r\nContent-Type: text/tab-separated-values\r\n\r\n"Campaign ID"\t"Plate Set ID"\t"No"\n\r\n----------------------------850116600781883365617864\r\nContent-Disposition: form-data; name="fasta"; filename="test-sequence_correct_5.fasta"\r\nContent-Type: application/octet-stream\r\n\r\n>P23G01_IgG1-1411:H:Q10C3:1/1:NID18\r\nCAGGTATTGAA\r\n\r\n----------------------------850116600781883365617864--\r\n'
postman_headers = Headers({'content-type': 'multipart/form-data; boundary=--------------------------850116600781883365617864', 'user-agent': 'PostmanRuntime/7.26.0', 'accept': '*/*', 'cache-control': 'no-cache', 'host': '10.0.5.13:80', 'accept-encoding': 'gzip, deflate, br', 'connection': 'keep-alive', 'content-length': '2455'})


async def stream(message):

    body = message.get("body", b"")
    if body:
        yield body

async def client_test_multipart():

    parser = MultiPartParser(client_headers, stream({"body": client_body}))
    form = await parser.parse()
    print([(k, v) for k, v in form.items()])
    return form

async def postman_test_multipart():

    parser = MultiPartParser(postman_headers, stream({"body": postman_body}))
    form = await parser.parse()
    print([(k, v) for k, v in form.items()])
    return form

loop = asyncio.get_event_loop()
loop.run_until_complete(client_test_multipart())
loop.run_until_complete(postman_test_multipart())

Expected behavior

client_test_multipart should read and return two files from the client_body as with postman_test_multipart and postman_body.

Actual behavior

client_test_multipart reads only one file from the request body produced by the client.

Debugging material

[('fasta', <starlette.datastructures.UploadFile object at 0x7f091c0b1a20>)]
[('attributes', <starlette.datastructures.UploadFile object at 0x7f091c0b1a58>), ('fasta', <starlette.datastructures.UploadFile object at 0x7f091c0b1828>)]

Environment

• OS: Linux
• Python version: 3.8
• Starlette version: 0.13.6

[aretasg]

@tomchristie any update on this ? python-multipart doesn’t seem to address this issue, however, this is quite blocking when using the UploadFile from FastAPI.

I’m using the requests library from python and I cannot manage to upload files, I always get a 422 Unprocessable Entity as response.

#1514 seemed to address this issue nicely given that the baize library seems much more active than python-multipart library. If this solution doesn’t suits you, what else are you planning to do ?

Does anyone currently have a workaround to use UploadFile from FastAPI and python requests as client ?

Thanks in advance for your reply

I still find it strange that after all this time since the issue has been raised the maintainers of python-multipart do not to even comment on the issue.

@hall-b python-multipart is only used for uploading multiple files at once. Perhaps you can do it one file at a time? If not, do try modifying the body of the request to make it standard as I did here.

[hall-b]

@tomchristie any update on this ? python-multipart doesn’t seem to address this issue, however, this is quite blocking when using the UploadFile from FastAPI.

I’m using the requests library from python and I cannot manage to upload files, I always get a 422 Unprocessable Entity as response.

#1514 seemed to address this issue nicely given that the baize library seems much more active than python-multipart library. If this solution doesn’t suits you, what else are you planning to do ?

Does anyone currently have a workaround to use UploadFile from FastAPI and python requests as client ?

Thanks in advance for your reply