[BUG] Uploading a single file on a multiple file field requires a try/except blog

[pydanny]

Describe the bug

If a file input is set to multiple=True and only a single file is selected on upload the form handler requires this try/except block or it throws a TypeError:

@rt('/upload-multiple')
async def post(files: list[UploadFile]):
    try: iter(files)
    except TypeError: files = [files]

Minimal Reproducible Example

from fasthtml.common import *
from pathlib import Path

app, rt = fast_app()

upload_dir = Path("filez")
upload_dir.mkdir(exist_ok=True)

@rt('/')
def get():
    return Titled("File Upload Demo",
        P('Upload 1 to display failure but multiples work fine'),
        Article(
            Form(Input(type="file", name="files", multiple=True),
                Button("Upload", type="submit", cls='contrast'),
                hx_post="/upload-multiple", hx_target="#result-multiple"),
            Div(id="result-multiple")
        )            
    )

def FileMetaDataCard(file):
    return Article(
        Header(H3(file.filename)),
        Ul(Li('Size: ',file.size),Li('Content Type: ',file.content_type))
    )    

@rt('/upload-multiple')
async def post(files: list[UploadFile]):
    # Uncomment to show current method to resolve the problem described
    # try: iter(files)
    # except TypeError: files = [files]
    cards = []
    for file in files:
        filebuffer = await file.read()
        (upload_dir / file.filename).write_bytes(filebuffer)
        cards.append(FileMetaDataCard(file))
    return cards    

serve()

Expected behavior

The list[UploadFile] type on a handler's arguments should cast a single submitted UploadFile to list[UploadFile]. Something like:

try: iter(files)
except TypeError: files = [files]

Environment Information Please provide the following version information:

• fastlite version: 0.0.11
• fastcore version: 1.7.13
• fasthtml version: 0.6.10

Confirmation Please confirm the following:

• [x] I have read the FAQ (https://docs.fastht.ml/explains/faq.html)
• [x] I have provided a minimal reproducible example
• [x] I have included the versions of fastlite, fastcore, and fasthtml
• [x] I understand that this is a volunteer open source project with no commercial support.