Change Content-Length for file downloads

Hello! I am trying to change the Content-Length header, as I will use Cloudflare Workers to download files from a R2 bucket. I tried by changing the header manually, but it doesnt make a change. Then I read that it was not possible to change that header, and that the only way to do so is by using Streams.

Now, my question is how should I do that? I tried to do it (see the code below), however it does not work. Any advice is very much appreciated!

firmwareBin = await env.R2.get(decodeURI(key));
let { readable, writable } = new FixedLengthStream(175104);
firmwareBin.body.pipeTo(writable);
return new Response(readable, firmwareBin);

firmwareBin = await env.R2.get(decodeURI(key));
let { readable, writable } = new FixedLengthStream(175104);
firmwareBin.body.pipeTo(writable);
return new Response(readable, firmwareBin);

Geektrader|ForexHistoryData.com•1/24/24, 8:46 PM

To change the Content-Length header in a Cloudflare Worker when serving files from an R2 bucket, you should use a FixedLengthStream to create a stream with a specified length. However, your current code snippet is missing a few steps. Here's how you can modify it:

firmwareBin = await env.R2.get(decodeURI(key));
let { readable, writable } = new FixedLengthStream(175104);

// You need to create a new Response object with the readable stream
// and set the headers you want to modify or keep from the original response.
let newHeaders = new Headers(firmwareBin.headers);
newHeaders.set('Content-Length', '175104'); // Set the desired Content-Length

// Pipe the original body to the writable stream of the FixedLengthStream.
await firmwareBin.body.pipeTo(writable);

// Return a new Response with the readable stream from the FixedLengthStream
// and the new headers.
return new Response(readable, {
headers: newHeaders,
status: firmwareBin.status,
statusText: firmwareBin.statusText
});

Make sure to replace '175104' with the actual length of the content you want to serve. This code creates a new Response object with the readable stream from the FixedLengthStream and sets the Content-Length header to the desired value. It also preserves the original status and status text from the firmwareBin response.