/database.db download should include content-length header

[simonw]

I can do this by modifying this function:

datasette/datasette/utils/asgi.py

Lines 248 to 270 in 02dc629

	async def asgi_send_file(
	send, filepath, filename=None, content_type=None, chunk_size=4096
	):
	headers = {}
	if filename:
	headers["Content-Disposition"] = 'attachment; filename="{}"'.format(filename)
	first = True
	async with aiofiles.open(str(filepath), mode="rb") as fp:
	if first:
	await asgi_start(
	send,
	200,
	headers,
	content_type or guess_type(str(filepath))[0] or "text/plain",
	)
	first = False
	more_body = True
	while more_body:
	chunk = await fp.read(chunk_size)
	more_body = len(chunk) == chunk_size
	await send(
	{"type": "http.response.body", "body": chunk, "more_body": more_body}
	)

[simonw]

I can use aiofiles.os.stat for this: https://github.com/Tinche/aiofiles/blob/master/aiofiles/os.py

[simonw]

Deployed and working:

% curl -I 'https://fivethirtyeight.datasettes.com/fivethirtyeight.db'
HTTP/1.1 200 OK
Date: Wed, 22 Jul 2020 04:59:23 GMT
Content-Type: application/octet-stream
Content-Length: 281845760
Connection: keep-alive
Set-Cookie: __cfduid=d550b15c99aa59144e49557ced64fc48a1595393963; expires=Fri, 21-Aug-20 04:59:23 GMT; path=/; domain=.datasettes.com; HttpOnly; SameSite=Lax
Via: 1.1 vegur
Cache-Control: max-age=14400
CF-Cache-Status: MISS
Accept-Ranges: bytes
cf-request-id: 04167d0c7100000540f98e8200000001
Expect-CT: max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
Server: cloudflare
CF-RAY: 5b6a978d89b30540-LAX