[Feature] Model.exists(query)

I found myself using this pattern a lot, where I want to know whether a document exists or not.

const user = await User.findOne({ name: 'Hafez' }).select('_id').lean();
if (user) {
  // do stuff
}

It works, but I find it unnecessarily verbose, if this is a common pattern, we could have a function that does the same thing under the hood, and returns true or false. Maybe something like

const userExists = await User.exists({ name: 'Hafez' }); // returns true or false
if (userExists) {
  // do stuff
}

Meanwhile, I was wondering if .select('_id').lean(); is the most performant way to find if a document exists, some insight here would be greatly appreciated.

[gianlucaparadise]

In the meantime, I’m using this code just to reduce verbosity:

mongoose.Model.exists = async function (options) {
  const result = await this.findOne(options).select("_id").lean();
  return result ? true : false;
};

This lets me run this code:

const userExists = await User.exists({ name: 'Hafez' }); // returns true or false
if (userExists) {
  // do stuff
}

[vkarpov15]

@num8er findOne() is more performant than count() in this case, unless your network is extremely slow and a couple bytes matter. Because count() behaves similarly to find() in that it doesn’t stop after it finds a matching doc, so if there’s no index then count() will always do a full collection scan.