Refactoring: returning a promise from a value or an existing promise

Question

My scenario

I used to have some node.js implementation done using callbacks but I am now refactoring my code to use Promises ins

Answer 1

I see only two problems.

1. If you want to explicitly return a rejected promise with a value, you should do that with Q.reject.

2. Calling .done() on promise means that the promise ends there. It cannot be chained further.

So, your code would look like this

exports.update = function (id, template) {
  if (!_isValid(template)) {
    return Q.reject(new Error('Invalid data', Error.INVALID_DATA));
  }

  return _update(id, template);
};

Now, the update function just returns a promise always. Its up to the callers to attach the success or failure handlers to it.