How to render response after stream finished pipe? - node.js

Question

This is what I want, server is a file server, when client asks for certain file, it'll stream that file back. Instead of koi-static, I try to do this, but the dest.jpg only contains 'Not found'.
client code:
var Koa = require('koa');
var Router = require('koa-router');
const HttpStatus = require('http-status');
const fs = require('fs');
const koaBody = require('koa-body');
const request = require('request');
const tempSaveFile = fs.createWriteStream('dest.jpg');
const writeStream = request.post('http://localhost:3456/getfile/src.jpg').pipe(tempSaveFile);
writeStream.on('finish', () => {
tempSaveFile.end();
console.log('Upload successful! ');
});
server code:
var Koa = require('koa');
var Router = require('koa-router');
const HttpStatus = require('http-status');
const fs = require('fs');
const koaBody = require('koa-body');
var app = new Koa();
var router = new Router();
const serve = require('koa-static');
router
.post([`/getfile/:fileName`],
(ctx) => {
const { params: { fileName } } = ctx;
console.error(`------- server will return ${fileName} --------`);
const readStream = fs.createReadStream(fileName).pipe(ctx.res);
readStream.on('finish', () => {
console.error('---- server finished stream ----');
ctx.status = HttpStatus.OK;
});
})
app.use(router.routes());
app.use(router.allowedMethods());
app.listen(3456);
When I change the server to use koa-static, client can gets the file successfully, did diff, look the same.
I suspect server returns too fast before it finishes, but another post said this is the way to wait for pipe to finish.
callback to handle completion of pipe
Any suggestions ? thanks !

Answer 1

ok, I added async, working now
const multiparty = require('multiparty');
const multer = require('koa-multer');
const request = require('request');
var app = new Koa();
var router = new Router();
const serve = require('koa-static');
const streamEnd = fd => new Promise((resolve, reject) => {
fd.on('end', () => {console.error('-- 51 --'); resolve(51); });
fd.on('finish', () => {console.error('-- 53 --'); resolve(53); });
fd.on('error', reject);
});
router
.get([`/getfile/:fileName`],
async (ctx) => {
const { params: { fileName } } = ctx;
console.error(`------- server will return ${fileName} --------`);
if (fs.existsSync(fileName)) {
const readStream = fs.createReadStream(fileName).pipe(ctx.res);
await streamEnd(readStream);
ctx.status = HttpStatus.OK;
} else {
console.error(`File ${fileName} doesnot exist`);
ctx.status = HttpStatus.INTERNAL_SERVER_ERROR;
}
})
app.use(serve('./customer'));
app.use(router.routes());
app.use(router.allowedMethods());
app.listen(3456);