JAVASCRIPT

mongoose unique

const mongoose = require('mongoose');

const userSchema = new mongoose.Schema({
  email: {
    type: String,
    unique: true // `email` must be unique
  }
});
const User = mongoose.model('User', userSchema);

mongoose unique field

var SimSchema = new Schema({
    msisdn     : { type : String , unique : true, required : true, dropDups: true },
    imsi       : { type : String , unique : true, required : true, dropDups: true },
    status     : { type : Boolean, default: true},
    signal     : { type : Number },
    probe_name : { type:  String , required : true }
});