mongoose (mongodb) Alias _id field

The easiest way is to specify alias in the schema:

let s = new Schema({
    _id: { type: String, alias: "ID" }
});

This automatically creates both getter and setter, so it is possible to use ID everywhere instead of _id.

Mongoose documentation on aliases

You would use a virtual attribute for that. As in:

yourSchema.virtual('ID').get(function() { return this._id; });