findOneAndUpdate with upsert sets schema defaults on the filter

[Kezzel]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Mongoose version

7.5.3

Node.js version

16.14.0

MongoDB server version

4.0 (documentDB)

Typescript version (if applicable)

No response

Description

When using findOneAndUpdate with upsert, the defaults of the schema is being applied to the filter.

The below steps to reproduce shows the problem. Inside castUpdate.js (

mongoose/lib/helpers/query/castUpdate.js

Line 129 in 1f64495

return { $setOnInsert: filter };

) the $setOnInsert is being set to the actual object of filter (not a copy).

Thus when later on applying defaults, the reference to filter makes it update both the $setOnInsert in the update AND the filter.

This caused the filter in findOneAndUpdate to NOT match the expected docs and thus create a new one.

The bug has been detected in 7.5.3, but the code suggests that this is still an issue in 8.0.0 (https://github.com/Automattic/mongoose/blob/e15940051f868f56c0dc9cf935e42b31703bb18b/lib/helpers/query/castUpdate.js#L129C3-L129C37).

A workaround exists with setting the $setOnInsert for ALL the default fields to the defaults your self, to avoid them being set in the filter.

Steps to Reproduce

const { Schema } = mongoose;

(async function(){
    console.log('connecting');
    var client = await mongoose.connect(`mongodb://localhost:10003/dev?tls=true&directConnection=true&retryWrites=false`,
    {
        user: process.env.DBUSER,
        pass: process.env.DBPASS,
    });
    console.log('connected');

    const schema = new Schema({
        my_field: Number,
        default_field: {type:String, default: 'default'}
    }, {
        collection: `test`,
        //disable versioning alltogether
        versionKey: false
    });
    
    schema.index({my_field:1});

    const Model = mongoose.model(`Test`, schema);
    //Make sure it is clean
    await Model.deleteMany({});

    //create a doc
    await Model.create({my_field:1, default_field:'NOT DEFAULT'});

    //get the doc based on a filter
    const filter = {
        my_field:1
    };
    let docs = await Model.find(filter);
    console.log(`Doc with a non-default`, docs);

    await Model.findOneAndUpdate(filter,{},{
        upsert:true
    });

    docs = await Model.find(filter);
    console.log(`Docs with a duplicate`,docs);

    console.log('done');
    process.exit();
})();

Expected Behavior

That the filter is NOT changed, and thus that the reproduction code would find the existing doc and not create a new one with a default.

[IslandRhythms]

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

(async function(){
    console.log('connecting');
    var client = await mongoose.connect(`mongodb://localhost:27017/`,
    {
        user: process.env.DBUSER,
        pass: process.env.DBPASS,
    });
    console.log('connected');

    const schema = new Schema({
        my_field: Number,
        default_field: {type:String, default: 'default'}
    }, {
        collection: `test`,
        //disable versioning alltogether
        versionKey: false
    });
    
    schema.index({my_field:1});

    const Model = mongoose.model(`Test`, schema);
    //Make sure it is clean
    await Model.deleteMany({});

    //create a doc
    await Model.create({my_field:1, default_field:'NOT DEFAULT'});

    //get the doc based on a filter
    const filter = {
        my_field:1
    };
    let docs = await Model.find(filter);
    console.log(`Doc with a non-default`, docs);

    await Model.findOneAndUpdate(filter,{},{
        upsert:true
    });

    docs = await Model.find(filter);
    console.log(`Docs with a duplicate`,docs);

    console.log('done');
    process.exit();
})();