Docs lacks on error handling: How handle errors with Busboy?

[cesco69]

I need to catch all error into on file event of busboy and pass the error to next() function.

I want also catch all busboy error and pass the error to next function.

    import * as Busboy from 'busboy';
    
    uploadAction(req: Request, res: Response, next: NextFunction) {
        let busboy: busboy.Busboy;
        // Create a new busboy instance
        // from doc, busboy constructor can raise an exception
        try {
            busboy = new Busboy({ headers: req.headers });
        } catch (err) {
            return next(err);
        } 
               
        busboy.on('file', (fieldname, file, filename) => {
            try {
                // my logic here...  
                throw new Error('Foo');  
            } catch (error) {
                // emit error to standard busboy event
                busboy.emit('error', error);
            }   
        });

        // listen all busboy error
        busboy.on('error', (err: string) => { 
            // remove busboy pipe
            req.unpipe(busboy);
            
            // ???????????????????????????????????
            // copy from https://github.com/expressjs/multer/blob/master/lib/make-middleware.js#L50
            req.on('readable', req.read.bind(req));
            busboy.removeAllListeners();

            // send error to next function
            next(err);
        });

        req.pipe(busboy);
    }

the next function is a global error handler that elaborate the error and send a response, eg.:

    app.use((err: Error, req: Request, res: Response, next: NextFunction) => {
        // some logic here...
        res.send({ error: error.message });
    });

Now, whitout the line

    req.on('readable', req.read.bind(req));

into:

    busboy.on('error', (err: string) => { 
        // remove busboy pipe
        req.unpipe(busboy);
            
        // ???????????????????????????????????
        // copy from https://github.com/expressjs/multer/blob/master/lib/make-middleware.js#L45
        req.on('readable', req.read.bind(req));
        busboy.removeAllListeners();

        // send error to next function
        next(err);
    });

the error handler can't send the response to the client..

But what is the purpose of:

    req.on('readable', req.read.bind(req));

In general: how handle correctly busboy error?

[mscdex]

But what is the purpose of:

    req.on('readable', req.read.bind(req));

You'd probably have to ask the multer devs, since that is the project you got the line from. My guess is it's used to drain any remaining data from the request stream. I would think you could alternatively do req.resume().

In general: how handle correctly busboy error?

The code you've shown seems to have captured every possibility AFAICT, but then again I don't use Express so I cannot say for sure.

[charmander]

blame → expressjs/multer#205