Mongoose: findOneAndUpdate doesn't return updated document

Question

Below is my code

var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/test');

var Cat = mongoose.model('Cat', {
    name: String,
    age: {type: Number, default: 20},
    create: {type: Date, default: Date.now} 
});

Cat.findOneAndUpdate({age: 17}, {$set:{name:"Naomi"}},function(err, doc){
    if(err){
        console.log("Something wrong when updating data!");
    }

    console.log(doc);
});

I already have some record in my mongo database and I would like to run this code to update name for which age is 17 and then print result out in the end of code.

However, why I still get same result from console(not the modified name) but when I go to mongo db command line and type "db.cats.find();". The result came with modified name.

Then I go back to run this code again and the result is modified.

My question is: If the data was modified, then why I still got original data at first time when console.log it.

Answer 1

Why this happens?

The default is to return the original, unaltered document. If you want the new, updated document to be returned you have to pass an additional argument: an object with the new property set to true.

From the mongoose docs:

Query#findOneAndUpdate

Model.findOneAndUpdate(conditions, update, options, (error, doc) => {   // error: any errors that occurred   // doc: the document before updates are applied if `new: false`, or after updates if `new = true` }); 

Available options

• new: bool - if true, return the modified document rather than the original. defaults to false (changed in 4.0)

Solution

Pass {new: true} if you want the updated result in the doc variable:

//                                                         V--- THIS WAS ADDED Cat.findOneAndUpdate({age: 17}, {$set:{name:"Naomi"}}, {new: true}, (err, doc) => {     if (err) {         console.log("Something wrong when updating data!");     }      console.log(doc); }); 

Answer 2

For anyone using the Node.js driver instead of Mongoose, you'll want to use {returnOriginal:false} instead of {new:true}.

2021 - Mongodb ^4.2.0 Update
{ returnDocument: 'after' }

Answer 3

So, "findOneAndUpdate" requires an option to return original document. And, the option is:

MongoDB shell

{returnNewDocument: true}

Ref: https://docs.mongodb.com/manual/reference/method/db.collection.findOneAndUpdate/

Mongoose

{new: true}

Ref: http://mongoosejs.com/docs/api.html#query_Query-findOneAndUpdate

Node.js MongoDB Driver API:

{returnOriginal: false}

2021 - Mongodb ^4.2.0 Update
{ returnDocument: 'after' }

Ref: http://mongodb.github.io/node-mongodb-native/3.0/api/Collection.html#findOneAndUpdate