Allow multipart requests without attaching files

[laipz8200]

Currently, a multipart request can only be sent when the files parameter is non-empty. This restriction limits cases where users might want to send data using multipart mode without attaching any files, which is possible in tools like Postman.

Proposed Change:

Instead of requiring files to be non-empty, we could determine the need for a multipart request based on whether files is None rather than its emptiness. This would allow users to send multipart requests without attaching files if needed.

Example Use Case:

• Sending form data using multipart mode without the need for a file upload.

Additional Context:

This change has been discussed and approved in the Q&A section with a maintainer. I’d be happy to work on this change.

I'd like to try to implement this feature, please assign this issue to me.

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• Initially raised as discussion Any Way to Send Multipart Requests Without Attaching Files? #3395

[sylann]

There is a way to solve this problem with current versions of httpx.
The documentation does not exactly demonstrate this use case, but it still gives the hint.

https://www.python-httpx.org/quickstart/#sending-multipart-file-uploads

multipart_form_data = {
    "field1": (None, "data"),
    "field2": (None, "data"),
}
http.post("your-url", files=multipart_form_data)

None corresponds to the "filename" of the field, which does not exist in this case.

Or, supposing you already have some dict (be careful though, it must be dict[str, str | bytes]),
You could convert it to a proper format like so:

data = {
    "field1": "data",
    "field2": "data",
}
multipart_form_data = {k: (None, v) for k, v in data.items()}
http.post("your-url", files=multipart_form_data)

[Anton-Shutik]

Might be related - #3522