Handling promises at router layer

[davidbayo10]

No description provided.

[dougwilson]

Hi @davidbayo10 thanks for the effort you put into this PR. You can find many, many discussions for making this exact change, including existing PRs which this duplicates. Unfortunately this cannot be added to Express 4, due to people already having existing code that is returning a promise and not expecting the rejection to call next, resulting in multiple calls to next occurring in existing code bases.

You can follow the most recent discussion on this here: #3604

If you think there is a better way to add promises than the existing PRs, you're welcome to make another and outline the differences from the existing proposals, but the PR would need to be made against the 5.0 branch (not master) 👍

[davidbayo10]

Hi @dougwilson, my main target on that development It is because an async function (async/await), which It is repeated in all controllers, looks like that:

async function (req, res, next) {
  try {
    const result = await asyncFunction();
    res.send(result);
  } catch (err) {
    next(err);
  }
}

I think this looks some better:

async function (req, res, next) {
  const result = await asyncFunction();
  res.send(result);
}

I this case, Layer class is responsible of catch and propagate a possible error