Unique validation not working in Mongoose

Question

I recognized this question has been asked before, but none of the solutions seemed to work for me.

I have a simple model I'm defining like this:

const mongoose = require('mongoose')
const { Schema } = mongoose

let subscriberSchema = new Schema({
  firstName: { type: String, required: true },
  email: { type: String, required: true, unique: true }
}, { timestamps: true })

let Subscriber = mongoose.model('Subscriber', subscriberSchema)

If I run the following (in the REPL, so no async issues), I'd expect to see an error being logged for the second call to create.

Subscriber.create({ firstName: "Landon", email: "[email protected]" })
Subscriber.create({ firstName: "Landon", email: "[email protected]" }, function(err) { 
  console.log("ERROR", err) 
})

Instead, I see "ERROR" null.

If I run a count query or a find query, I can see both models were created. What am I doing wrong?

Edit

Here are a few of the things I've already tried:

• Restart MongoDB after adding index
• Removing all of the existing records so there are no existing records that could violate the uniqueness constraint
• Defining the email attribute all of these ways (I've seen different implementations in different places): { type: String, required: true, unique: true }, { type: String, required: true, index: true, unique: true }, { type: String, required: true, index: { unique: true } }.

Answer 1

Actually, unique option for validation working,how?Follow these steps:
1)set unique: true for certain field in schema(example "email")
2)drop whole db
3)restart node server
4)test in postman and you will see than now works

Cheers.

Answer 2

Make autoIndex: true while connecting to the database.

mongoose
.connect('connection url', {
    useUnifiedTopology: true,
    useNewUrlParser: true,
    autoIndex: true, //make this true
})
.then(() => {
    console.log('Connected to mongoDB');
});