[SOLVED] Possible to export an async function from a Mongoose.js model to simulate findOne() with callback

Possible to export an async function from a Mongoose.js model to simulate findOne() with callback

I recently updated a large project to the newest version of Mongoose and realized that support for callbacks in findOne() have been dropped. I'm curious if anyone has recommendations for the most low-impact way to update my codebase. Currently, in my users.js model I'm using this code:

module.exports.getOne = function(query, callback) {
  User.findOne(query, callback);
}

and then calling the function like so:

User.getOne({ 'username' : username }, function(err, user) { (SOME CODE) });

Is there a way to rewrite the getOne function using the newer async method that would essentially allow me to leave all the calls as-is (i.e. allows me to simply pass function to the call that will have access to the data in findOne)? Or do I just need to bite the bullet and rewrite every call with the new format?

Any suggestions appreciated!

Solution

You can update your getOne method as below to keep the functionality as-is and leverage the new syntax of Mongoose queries.

module.exports.getOne = function (query, callback) {
  User.findOne(query)
    .exec()
    .then(result => callback(null, result)) // Call the callback with the result as second parameter on success
    .catch(err => callback(err)); // Call the callback with the error on failure
};

The findOne method returns a Query which is also thenable, it is recommended to use exec() to get a better stack trace in case of errors.