Option to encode form data

[mattiasrubenson]

I'm using httpx to send form data to a web site with this code, modified for clarity:

        client = httpx.AsyncClient()
        poster = "id\tdistrict\r\n1\tMalmö"
        data = {
            "action": "insert",
            "filter": "0",
            "poster": poster,
            "button": "Importera+data"
        }
        await client.post(f"{base_url}/jsp/admin/right_admin_import_studentstatus.jsp", data=data)

The problem with this is that the "ö" becomes urlencoded into "%C3%B6", instead of the "%F6" that the web service would decode into "ö".

I managed to fix this problem by adding encoding="ISO-8859-1" in httpx/_content:

def encode_urlencoded_data(
    data: RequestData,
) -> Tuple[Dict[str, str], ByteStream]:
    plain_data = []
    for key, value in data.items():
        if isinstance(value, (list, tuple)):
            plain_data.extend([(key, primitive_value_to_str(item)) for item in value])
        else:
            plain_data.append((key, primitive_value_to_str(value)))
    body = urlencode(plain_data, doseq=True, encoding="ISO-8859-1").encode("utf-8") # THIS LINE IS MODIFIED
    content_length = str(len(body))
    content_type = "application/x-www-form-urlencoded"
    headers = {"Content-Length": content_length, "Content-Type": content_type}
    return headers, ByteStream(body)

Maybe httpx could support optionally adding an encoding to your data for cases like this? Or maybe I'm going about this in a stupid way? :)