This is on Node/Express/Typescript. I'm trying get an image on my file system, stream it to a zip file, and then stream this zip file to the client. I have to make sure every step is streamed since this will expand to zipping up multiple files, which need to be streamed to the client as a zip.
I have the following code:
import express, { Application, Request, Response } from "express";
import fs from "fs";
import stream from "stream";
import archiver from "archiver";
app.get("/images", async (req: Request, res: Response) => {
const r = fs.createReadStream("appicon.png");
const ps = new stream.PassThrough();
// stream the image
stream.pipeline(
r,
ps,
(err) => {
if (err) {
console.log(err);
return res.sendStatus(400);
}
}
);
// zip the image and send it
let archive = archiver("zip");
archive.on("end", () => {
console.log(archive.pointer() + " total bytes");
console.log("archiver finalized");
})
archive.on('error', (err) => {
return res.status(500).send({
message: err
});
})
res.attachment('output.zip');
ps.pipe(archive);
archive.pipe(res);
archive.finalize();
});
However, when I access my /images route, I get an output.zip file which is empty.
I feel like I'm messing up the order of my pipes somehow.
What am I missing?
I figured out the issue. Here is the code that works:
app.get("/images", async (req: Request, res: Response) => {
const r = fs.createReadStream("appicon.png");
const ps = new stream.PassThrough();
stream.pipeline(
r,
ps,
(err) => {
if (err) {
console.log(err);
return res.sendStatus(400);
}
}
);
//r.pipe(ps); // alternative way to do it without pipeline
// zip the image and send it
let archive = archiver("zip");
archive.on("end", () => {
console.log(archive.pointer() + " total bytes");
console.log("archiver finalized");
})
archive.on('error', (err) => {
return res.status(500).send({
message: err
});
})
// name the output file
res.attachment("output.zip");
// pipe the zip to response
archive.pipe(res);
// add the image from stream to archive
archive.append(ps, {name: "image.png"});
archive.finalize();
});
I had to use archive.append(ps, {name: "image.png"}); to add my image stream to the zip archive.