Custom Error Messages with Mongoose

Question

So according to the mongoose docs, you are supposed to be able to set a custom error message in the schema like so:

 var breakfastSchema = new Schema({
  eggs: {         


        

Answer 1

you can add a custom async validator. for example:

 {
      validator: (value) => {
        return UserModel.findOne({ email: value })
          .then(user => Promise.resolve(user == null))
          .catch(error => Promise.reject(false));
      },
      message: "User with this email already exists"
 }