Suggestion about error handler in express
I have this idea when I am at Streaming Content with Express (2).
As the tutorial states, error handler of express always respond with HTML describing the error the server has.
If we change the Content-Type
to something except text/html
, for example, application/json
, then browser will receive a HTML response while the header of which is not application/json
. Browser will be confused due to header and content mismatch.
According to the last step of Streaming Content with Express (2), when I navigate to http://localhost:3000/articles?type=json
, the response looks like this in the browser:
Maybe we can reset the response type in the error handler to inform the clients of the correct Content-Type
.
// render the error page res.type('text/html') res.status(err.status || 500); res.render('error');
Comments
-
Another observation about express is streaming error handling.
Say pipe some stream tores
.someStream.pipe(res)
And something goes wrong during the process before
end
event of the stream emitted.someStream.destroy()
Before
someStream.destroy()
being invoked, HTTP headers have already been sent to the client.
If I propagateError [ERR_STREAM_PREMATURE_CLOSE]
tonext()
function of the route handler, express will also invokeres.render('error');
inapp.js
to respond to the HTTP request. Then express will complain thatError [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
So I would like to know what is the appropriate way to handle error when piping stream to HTTP response. The default behavior of express doesn't seem to be the best solution.
0 -
const { finished } = require('stream') // handler setup etc etc handler.get('/foo/bar', (req, res, next) => { const stream = createStream(req.data.whatever) finished(stream, (err) => { if (err) return next(err) res.end('finished') next() }) })
Streams can close for various reasons, using the
finished
function covers all the cases.If you're looking to pipe you can use
stream.pipeline
to combine the best of both.pipe
andfinished
:const { pipeline } = require('stream') // handler setup etc etc handler.get('/foo/bar', (req, res, next) => { const stream = createStream(req.data.whatever) pipeline(req, stream, res, next) })
0
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