Mongoose: how to define a combination of fields to be unique?

Question

If I had a schema like this:

var person = new Schema({
  firstName:  String,
  lastName: String,
});

Answer 1

const personSchema = new Schema({ firstName:  String, lastName: String });
const person = mongoose.model('recipients', personSchema);
person.createIndexes();

You might need to get rid of all duplicates in the collection or do it the faster and easy way :

Edit your Code, Drop the Collection and then restart Mongo.