如何使用co in express全局处理错误

Question

I am new to nodejs and co. I am using co in express like below, since it is more like the async await I am used to in c# and I think the code is more readable.

(req, res) => {
        co(function*(){
            var book = req.book;

            book.bookId = req.body.bookId;
            book.title = req.body.title;               
            book.read = req.body.read;

            yield book.save();

            res.json(book);
        }).catch(err => res.status(500).send(err));
    }

The problem is that everytime I call co, I have to handle the exception in the catch function. I would like to handle exceptions globally instead, in a middleware perhaps. But as far as I know, co swallows exceptions that are not handled, so I have to handle catch in every call to co.

One possible solution I came up with was to wrap co in a function that automatically handles the exceptions in the catch function and use that wrapped function instead. Something like:

var myCo = function(genFunc){
   return co(genFunc)
          .catch(err => someGlobalErrorHandler(err))
};

Is there a better or more standard way?

Answer 1

You can use standard express error handler width this small lib :

var co = require('co');

module.exports = function wrap(gen) {
  var fn = co.wrap(gen);

  if (gen.length === 4) {
    return function(err, req, res, next) {
      return fn(err, req, res, next).catch(next);
    }
  }

  return function(req, res, next) {
    return fn(req, res, next).catch(next);
  };
};