Typescript sees the Boolean Constructor Type as Date when using Mongoose

[molina95]

Prerequisites

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

Mongoose version

8.4.0

Node.js version

21.7.1

MongoDB server version

6.6.2

Typescript version (if applicable)

5.4.5

Description

Whenever I try to make an Schema with a property of the Type Boolean Constructor the typescript server sees it as being of the type Date.

error TS2322: Type 'boolean' is not assignable to type 'Date'.

22 course.isPublished = false;
~~~~~~~~~~~~~~~~~~

Found 1 error in src/updatemongo.ts:22

Steps to Reproduce

I just create a TypeScript project with this tsconfig

{
"compilerOptions": {
"target": "ES2015",
"module": "commonjs",
"esModuleInterop": true,
"moduleResolution": "Node",
"forceConsistentCasingInFileNames": true,
"strict": true,
"skipLibCheck": true,
"rootDir": "src",
"outDir": "dist"
}
}

install the latest mongoose available using npm and
try to make an Scheme like this.

import mongoose, { Mongoose } from "mongoose";
const courseSchema = new mongoose.Schema({
name: String,
author: String,
tags: [String],
date: { type: Date, default: Date.now },
prices:Number,
isPublished: Boolean
});

const Course = mongoose.model('Course', courseSchema);

async function updateCourse(id:any) {
const course = await Course.findById(id);
if (!course) return;
course.isPublished = false; //tsc won't compile because it will see it as being of type Date
course.author = 'Another Author';
}

updateCourse("none");

Expected Behavior

Typescript should see it as being of type Boolean

[vkarpov15]

I'm unable to repro. The following script compiles correctly with Mongoose 8.4.0 and TypeScript 5.4.5. Please modify the following script to demonstrate your issue. Also, just to be clear, do you get this error when you compile TypeScript, or does this error just show up when you hover over isPublished in your code editor?

import mongoose, { Mongoose } from "mongoose";
const courseSchema = new mongoose.Schema({
  name: String,
  author: String,
  tags: [String],
  date: { type: Date, default: Date.now },
  prices:Number,
  isPublished: Boolean
});

const Course = mongoose.model('Course', courseSchema);

async function updateCourse(id:any) {
  const course = await Course.findById(id);
  if (!course) return;
  course.isPublished = false; //tsc won't compile because it will see it as being of type Date
  course.author = 'Another Author';
}

updateCourse('none');

Output:

$ ./node_modules/.bin/tsc --strict --target ES2015 --moduleResolution node --esModuleInterop gh-14630.ts 
$ head node_modules/typescript/package.json 
{
    "name": "typescript",
    "author": "Microsoft Corp.",
    "homepage": "https://www.typescriptlang.org/",
    "version": "5.4.5",
    "license": "Apache-2.0",
    "description": "TypeScript is a language for application scale JavaScript development",
    "keywords": [
        "TypeScript",
        "Microsoft",
$ 

[molina95]

I'm unable to repro. The following script compiles correctly with Mongoose 8.4.0 and TypeScript 5.4.5. Please modify the following script to demonstrate your issue. Also, just to be clear, do you get this error when you compile TypeScript, or does this error just show up when you hover over isPublished in your code editor?

import mongoose, { Mongoose } from "mongoose";
const courseSchema = new mongoose.Schema({
  name: String,
  author: String,
  tags: [String],
  date: { type: Date, default: Date.now },
  prices:Number,
  isPublished: Boolean
});

const Course = mongoose.model('Course', courseSchema);

async function updateCourse(id:any) {
  const course = await Course.findById(id);
  if (!course) return;
  course.isPublished = false; //tsc won't compile because it will see it as being of type Date
  course.author = 'Another Author';
}

updateCourse('none');

Output:

$ ./node_modules/.bin/tsc --strict --target ES2015 --moduleResolution node --esModuleInterop gh-14630.ts 
$ head node_modules/typescript/package.json 
{
    "name": "typescript",
    "author": "Microsoft Corp.",
    "homepage": "https://www.typescriptlang.org/",
    "version": "5.4.5",
    "license": "Apache-2.0",
    "description": "TypeScript is a language for application scale JavaScript development",
    "keywords": [
        "TypeScript",
        "Microsoft",
$ 

This is the full code I have and not only the short snippet to get to the error

updatemongo.ts

import mongoose, { Mongoose } from "mongoose";

const uri = 'mongodb+srv://<user>:<password>@<mongo>/mongo-exercises?retryWrites=true&w=majority&appName=Molina1';
mongoose.connect(uri)
    .then(() => console.log('Connected to Mongo Database...'))
    .catch(err => console.error('Could not connect to Mongo Database...', err));

const courseSchema = new mongoose.Schema({
    name: String,
    author: String,
    tags: [String],
    date: { type: Date, default: Date.now },
    prices:Number,
    isPublished: Boolean
});

const Course = mongoose.model('Course', courseSchema);

async function updateCourse(id:any) {
    const course = await Course.findById(id);
    if (!course) return;
    course.isPublished =  false as any;
    course.author = 'Another Author';
    course.isPublished = true;

    course.set({
        isPublished:true,
        author:'Another Author'
    }); 

    const result = await course.save();
    console.log(result);
} 

/*async function updateCourse(id:any) {
    const course = await Course.updateOne({_id:id},{
        $set:{
            author:'Mosh',
            isPublished:true,
        },
        $currentDate:{
            date:true
        }
    });
    
    console.log(course);
}*/

updateCourse("665a0ee68b40030cbec8dd57"); 

Both the code editor and the tsc command line would tell me that the data type is of type Date when using TypeScript.
This is the message I get from tsc

tsc
src/updatemongo.ts:24:5 - error TS2322: Type 'boolean' is not assignable to type 'Date'.

24     course.isPublished = true;
       ~~~~~~~~~~~~~~~~~~

Found 1 error in src/updatemongo.ts:24

And this is the error I get on the IDE from the typescript server:

Let me paste the package.json and the package-lock.json, and the tsconfig.json
It may help

package.json
package-lock.json
tsconfig.json

And I am sure I am on the versions of mongo, tsc and mongoose I placed at the start of the ticket.
If there is other info I can give you other than the one I just placed here, please let me know.

[vkarpov15]

Very strange, this issue doesn't seem to happen if Mongoose is symlinked into node_modules, which is what we often use for debugging. But if you npm install mongoose, this error shows up.

Strangely enough, this error doesn't show up in TypeScript Playground either.

[vkarpov15]

As a workaround, you can use isPublished: 'Boolean', that seems to be inferred correctly

[molina95]

Thanks that worked for me. but is really weird if you see Typescript playground loads it as date then it settles into boolean, but adding the simple quotes worked fine.

[vkarpov15]

We're still working on figuring out this issue, isPublished: Boolean should work. Just providing a temporary workaround so you're not blocked on us :)