koa-write 是做什么的？

Question

My project uses the Koa framework, and I'm looking for a way to replace Express's res.write to stream large datasets into a csv.

Can I use koa-write to do this? Something like:

var write = require('koa-write');

router.get('/', (ctx, next) => {
    ctx.response.set('Content-Type', 'text/csv');
    ctx.response.set('Content-Disposition', 'attachment; filename=data.csv');
    write(ctx, "1,2,3,4,5\n");
});

I tried it but it doesn't seem to work.

Answer 1

you can just create a Readable stream and assign to ctx.body

const Koa = require("koa");
const { Readable } = require("stream");

const app = new Koa();
const s = new Readable();

app.use((ctx) => {
  if (ctx.request.url === "/") {
    ctx.body = s;
    s.push('"1,2,3,4,5\n');
    s.push("test test");
    s.push(null); // indicates end of the stream
  } else {
    ctx.throw(404);
  }
});

app.listen(8080);

Or if you already have a stream, just assign to body. otherwise, create a new Stream and push data to it. Terminate the stream with null