mongoose ver 6 deleteMany() removes ALL documents when search options contains field not from schema

Prerequisites

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

Mongoose version

6.5.4

Node.js version

12.22.12

MongoDB server version

4.4

Description

There is a collection with documents, there is it schema. At the same time, not all fields of documents are described in the schema, i.e. some documents have fields not described in the schema. We call model.deleteMany({x:<some_value>}) where “x” not in schema. This call removes all documents in the collection.

This behavior was not in version 5

Steps to Reproduce

Simple nodejs program, file index.js

const mongoose = require('mongoose');

mongoose.connect('mongodb://127.0.0.1:27017/mongoose_test', {});

// User model
const User = mongoose.model('User', {
	name: { type: String },
	age: { type: Number }
	// type: { type: Number }
});

User.deleteMany({}, function (err, result) { // clear collection
  if (err) return console.log(err)
  User.collection.insertMany([  // with .collection - through mongo driver, without mongoose validation
    { name: 'Vadim', age: 30 },
    { name: 'Dmitry', age: 27 },
    { name: 'Nikita', age: 20, type: 2 },
    { name: 'Mark', age: 45 },
    { name: 'Serge', age: 40, type: 2 }],
    function (err, result) {
      if (err) return console.log(err)
      console.log(result)
      // now want to delete documents with type==2
      User.deleteMany({ type: 2 }, function (err, result) {
        if (err) return console.log(err)
        console.log(result)
      })
    }
  )
}
)

file package.js:

{
  "name": "mongoose-issue",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "mongoose": "^6.5.4"
  }
}

result:

C:\Bin\node-v12.22.12-win-x64\node.exe .\index.js
{acknowledged: true, insertedCount: 5, insertedIds: {…}}
{acknowledged: true, deletedCount: 5}

same program in mongoose 5.13.15 produce

C:\Bin\node-v12.22.12-win-x64\node.exe .\index.js
(node:17288) DeprecationWarning: current URL string parser is deprecated, and will be removed in a future version. To use the new parser, pass option { useNewUrlParser: true } to MongoClient.connect.
(node:17288) [MONGODB DRIVER] Warning: Current Server Discovery and Monitoring engine is deprecated, and will be removed in a future version. To use the new Server Discover and Monitoring engine, pass option { useUnifiedTopology: true } to the MongoClient constructor.
{result: {…}, ops: Array(5), insertedCount: 5, insertedIds: {…}}
insertedCount: 5
insertedIds: {0: ObjectID, 1: ObjectID, 2: ObjectID, 3: ObjectID, 4: ObjectID}
ops: (5) [{…}, {…}, {…}, {…}, {…}]
result: {ok: 1, n: 5}
__proto__: Object
{n: 2, ok: 1, deletedCount: 2}
deletedCount: 2
n: 2
ok: 1
__proto__: Object

Expected Behavior

Expected behavior - exactly as in version 5 - only documents with {x:<some_value>} should be deleted.

[Vadim725]

@hasezoey thanks, after more careful study of the problems, I also found other issue - #10946 BTW - despite of strictQuery - it is very dangerous default in v6

[hasezoey]

Is there any fix for this issue in the works? We’ve ran into a similar issue

because this would be a breaking change, it has been put off to the next major version, see #11861

the manual fix would be to use strictQuery: false as either a schema-option, or on a per-query level