mongoose unique: true not work [duplicate]

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Unique index in mongoose not working 1 answer
Mongoose Unique index not working! 13 answers

why mongoose unique not work at all in this script

  var child_process = require('child_process');
  // Load required packages
  child_process.exec("mongo test --eval 'db.users.drop();'", function(err){
  var mongoose = require('mongoose');

  console.log(mongoose.version);
  mongoose.connect('mongodb://localhost:27017/test');
  // Define our user schema

  var json = {};
  json.phone = { type: String, required: true, unique: true};
  var UserSchema = new mongoose.Schema(json);
  var Model = mongoose.model('user', UserSchema);

  var jp = new Model({ phone: "123456"});
  mongoose.connection.on('open', function(){
    console.log(jp);
    jp.save(function(err){
      console.log(err);
      var jp2 = new Model({ phone: "123456"});
      console.log(jp2);
      jp2.save(function(err){
        console.log(err);
        process.exit();
      });
    })
  });
});

I'm quite confused, the result is like

3.8.20
{ phone: '123456', _id: 54856cceb5b40f7a88fcc2af }
null
{ phone: '123456', _id: 54856cceb5b40f7a88fcc2b0 }
null

Thank you for your help.

This happens because you're saving the duplicated document before mongoose has finished creating the index. Mongoose creates the indexes on the go, after your app has started.

So, to ensure that your document will be saved only after the indexes were created, you have to listen to the index event of your model. For example:

Model.on('index', function (error) {
  console.log(jp);
  jp.save(function(err){
    console.log(err);
    var jp2 = new Model({ phone: "123456"});
    console.log(jp2);
    jp2.save(function(err){
      console.log(err);
      process.exit();
    });
  })
});

Now, when you try to save the second document (the duplicated one), your MongoDB will raise an error, because your save calls will just run after the indexes were created.