cannot pipe request after body-parser

[fschwic]

I'm using body-parser to limit the size of a POST body. Adding the following line a request with some 3MB stucks on '100 continue'. No data is written.

app.use(bodyParser.raw({ limit: '5mb' }));

A request with 400kB is successful. Removing the above line the 3MB request (and larger requests) work fine.
I'm using version 1.12.3. Maybe I have overseen something!?

[dougwilson]

Hm, I'm not sure. I just made the following app and it works fine with a Expect: 100-continue:

var bodyParser = require('body-parser')
var express = require('express')

var app = express()
.use(bodyParser.raw({ limit: '5mb' })
use(function (req, res) {
  res.end('I saw ' + rew.body.length + ' bytes in the body')
})

express.listen(3000)

It's very important that you do not have a checkContinue listener on your server (https://nodejs.org/api/http.html#http_event_checkcontinue), because that is most likely what would cause your request to hang on a 100 continue. You can also see if the request even gets into this module but running your app with the environment DEBUG=body-parser:* and pasting what it prints to STDERR here.

[fschwic]

With DEBUG set I get the following (incl. request headers).

body-parser:raw content-type "application/octet-stream" +33s
body-parser:raw content-encoding "identity" +0ms
body-parser:raw read body +0ms
body-parser:raw parse body +8ms
{ 'user-agent': 'curl/7.35.0',
  host: 'localhost:8081',
  accept: '*/*',
  'content-type': 'application/octet-stream',
  'x-allowed-downloads': '30',
  'content-length': '3744928',
  expect: '100-continue' }

The +33s is after several requests. After starting the node app there appear 0ms with the first request.

The request I do with curl:

curl -i -X POST -H "Content-Type: application/octet-stream" -H "X-Allowed-Downloads: 30" 'http://localhost:8081/uploads' --data-binary @Downloads/some.zip 

Reading from the request, writing to a file in this way:

var writeable = fs.createWriteStream("./uploads/" + file);
  writeable.on('finish', function(){
    res.status(204).end();
  });
  var readable = req;
  readable.pipe(writeable);

Thanks for the quick reply!

[dougwilson]

Ah, thanks, that fss usage is where your problem is. You can only read a stream one time in Node.js. req was already read into req.body ny this module, so your req.pipe is what's hanging. You just need to do writable.end(req.body) and remove readable.pipe(writeable).

[fschwic]

With the answer it is so obvious. But I never had found it alone.
:-)
Very special thanks!!!

[dougwilson]

My pleasure :)