mongooseInstance.array.addToSet weird behavior

[theoscat]

Hello,

I have the following code:
mongooseInstance.array.addToSet({user: uid, name: "theName"}); mongooseInstance.save(function(err,mongooseInstance){ if(err){ //DO something } else { //do something else with mongooseInstance } });
Knowing that the mongooseInstance.array already contain the object {user: uid, name: "theName"}.
There isnt duplicate entries in the db but my mongooseInstance after the save contain two object {user: uid, name: "theName"}.

mongooseInstance.array = [{user: uid, name: "theName"},{user: uid, name: "theName"}]

I can get what i want by querying the mongooseInstance again but it doesnt seems really effective.

[vkarpov15]

Can you clarify? I don't quite understand your issue.

[theoscat]

Ok i will try to clarify my problem hopping im not wasting your time.

mongooseInstance.objectArray = [];
mongooseInstance.objectArray.addToSet({user: objectId("anObjectId"), name: "aSimpleName"});
mongooseInstance.save();


//console.log(mongooseInstance.objectArray) => [{user: objectId("anObjectId"), name: "aSimpleName"}]

//Everything is fine !

//Now if i add the same object to my objectArray:

mongooseInstance.objectArray.addToSet({user: objectId("anObjectId"), name: "aSimpleName"});
mongooseInstance.save();

console.log(mongooseInstance.objectArray) => [{user: objectId("anObjectId"), name: "aSimpleName"} , {user: objectId("anObjectId"), name: "aSimpleName"}]

//Here i have the duplicate object in my objectArray, then if i query the instance back from the db:

var freshInstance = MongooseModel.find(mongooseInstance.id);

console.log(freshInstance.objectArray) =>  [{user: objectId("anObjectId"), name: "aSimpleName"}]

I dont understand why after the second addSet, i get a duplicate object in my objectArray even if in the db it wont be saved.

[vkarpov15]

The below script works as expected for me:

'use strict';

var assert = require('assert');
var mongoose = require('mongoose');
var Schema = mongoose.Schema;

mongoose.connect('mongodb://localhost/gh4128');
mongoose.set('debug', true);

var schema = new Schema({
  objectArray: [{ name: String }]
});

var Model = mongoose.model('Test', schema);

Model.create({}, function(error, m) {
  assert.ifError(error);
  var id = new mongoose.Types.ObjectId();
  m.objectArray.addToSet({ _id: id, name: 'val' });
  console.log(m);
  m.save(function(error) {
    assert.ifError(error);
    m.objectArray.addToSet({ _id: id.toString(), name: 'val' });
    console.log(m);
    process.exit(0);
  });
});

output:

$ node gh-4128.js 
Mongoose: tests.insert({ _id: ObjectId("5730a8bd0dd65094198bbf0e"), objectArray: [], __v: 0 })   
{ objectArray: [ { name: 'val', _id: 5730a8bd0dd65094198bbf0f } ],
  _id: 5730a8bd0dd65094198bbf0e,
  __v: 0 }
Mongoose: tests.update({ _id: ObjectId("5730a8bd0dd65094198bbf0e") }) { '$addToSet': { objectArray: { '$each': [ { _id: ObjectId("5730a8bd0dd65094198bbf0f"), name: 'val' } ] } }, '$inc': { __v: 1 } }  
{ objectArray: [ { name: 'val', _id: 5730a8bd0dd65094198bbf0f } ],
  _id: 5730a8bd0dd65094198bbf0e,
  __v: 1 }

Can you see if you can modify the above script to repro your issue? Also, can you clarify which version of mongoose?

[theoscat]

Hi,

sorry for the delay.
Im using mongoose 4.4.13.

I do agree, your piece of code works as expected.
However in my use case i dont have an id also my Schema is not the same:

'use strict';

var assert = require('assert');
var mongoose = require('mongoose');
var Schema = mongoose.Schema;

mongoose.connect('mongodb://localhost/gh4128');
mongoose.set('debug', true);

var schema = new Schema({
    objectArray: []
});

var Model = mongoose.model('Test', schema);

Model.create({}, function(error, m) {
    assert.ifError(error);
    m.objectArray.addToSet({name: 'val' });
    console.log(m);
    m.save(function(error) {
        assert.ifError(error);
        m.objectArray.addToSet({name: 'val' });
        m.objectArray.addToSet({name: 'val' });
        console.log(m);

        m.save(function(error){
            console.log(m);
            process.exit(0);
        });

    });
});

output:

Mongoose: tests.insert({ _id: ObjectId("573340ccb9808f8879cb05ad"), objectArray: [], __v: 0 })   
{ objectArray: [ { name: 'val' } ],
  _id: 573340ccb9808f8879cb05ad,
  __v: 0 }
Mongoose: tests.update({ _id: ObjectId("573340ccb9808f8879cb05ad") }) { '$addToSet': { objectArray: { '$each': [ { name: 'val' } ] } }, '$inc': { __v: 1 } }  
{ objectArray: [ { name: 'val' }, { name: 'val' }, { name: 'val' } ],
  _id: 573340ccb9808f8879cb05ad,
  __v: 1 }
{ objectArray: [ { name: 'val' }, { name: 'val' }, { name: 'val' } ],
  _id: 573340ccb9808f8879cb05ad,
  __v: 2 }
Mongoose: tests.update({ _id: ObjectId("573340ccb9808f8879cb05ad") }) { '$addToSet': { objectArray: { '$each': [ { name: 'val' }, { name: 'val' } ] } }, '$inc': { __v: 1 } }  

If you look in the db, you'll se that there is just one item in objectArray.
This is what i want in fact, but if you look the last objectArray log, you can see that the array contains 3 val and that's the thing i dont understand.

[NeXTs]

Wow!
So that's possible to update document by calling array update operators right from instance!

It's not documented at mongoose website at all. Where I can read about this?

How can I do this

post.contributors.addToSet({
  $each: _.map(users, function(item){ return item._id })   // guessed, wrong syntax, not working
}, cb);

instead of this?

Post.update({post: post.title}, {
  $addToSet: {  // working
    contributors: {
      $each: _.map(users, function(item){ return item._id })
    }
  }
}, cb);

Where contributors is array of Objectids from other collection.

[vkarpov15]

Not sure how well documented it is but you can do doc.array.addToSet() followed by doc.save() and that does a $addToSet under the hood

[NeXTs]

@vkarpov15 what about $each helper?
Exactly this part wasn't obvious for me

[vkarpov15]

Call addToSet multiple times. In your example in an _.each