[TS] model, new Model, Document and HydratedDocument: DocType typing inconsistencies

[andreafdaf]

Prerequisites

• I have written a descriptive issue title

Mongoose version

6.6.5

Node.js version

16.18.0

MongoDB server version

6.0

Typescript version (if applicable)

4.8.4

Description

This issue is possibly related to #10302

We are migrating from v5 to v6 and the situation in v6 is weirder than in v5.

It seems to me (in my really humble opinion) that DocType is not working as expected both when specifying what we pass to new MyModel but also when trying to tell us what comes back from model.

I think that the main issue is that DocType is only used to tell the Document what it should accept in some methods or the lean shape it returns, while it is HydratedDocument that merges the definition of DocType and Document, leaving some edge cases on how HydratedDocument handles it's DocType and how it is handled when calling new MyModel()

Steps to Reproduce

// ./schema.ts
import { Schema } from 'mongoose'

export const MySchema = new Schema({
  field: { type: String }
})

OK:

import { model } from 'mongoose'
import { MySchema } from './schema'

const MyModel = model('My', MySchema)

const myDocument = new MyModel({ field: 'a' })
const { field } = myDocument

import { model } from 'mongoose'
import { MySchema } from './schema'

const MyModel = model<{ field: string }>('My', MySchema)

const myDocument = new MyModel({ field: 'a' })
const { field } = myDocument

import { model } from 'mongoose'
import { MySchema } from './schema'

const MyModel = model('My', MySchema)

const myDocument = new MyModel<any>({ field: 'a' })
const { field } = myDocument // it doesn't care that I passed <any> to MyModel, it makes no difference and behaves like above

import { model, HydratedDocument } from 'mongoose'
import { MySchema } from './schema'

const MyModel = model('My', MySchema)

const myDocument: HydratedDocument<any> = new MyModel({ field: 'a' })
const { field } = myDocument // myDocument is 'any'

KO:

import { model, Schema } from 'mongoose'
import { MySchema } from './schema'

const MyModel = model<any>('My', MySchema)

const myDocument = new MyModel({ field: 'a' })
const { field } = myDocument // Property 'field' does not exist on type 'Document<unknown, any, unknown> & { _id: ObjectId; }'.ts(2339)

import { model, Schema } from 'mongoose'
import { MySchema } from './schema'

model('My', MySchema)
const MyModel = model<any>('My')

const myDocument = new MyModel({ field: 'a' })
const { field } = myDocument // Property 'field' does not exist on type 'Document<unknown, any, unknown> & { _id: ObjectId; }'.ts(2339)

import { model, Schema } from 'mongoose'
import { MySchema } from './schema'

model('My', MySchema)
const MyModel = model('My')

const myDocument = new MyModel<any>({ field: 'a' })
const { field } = myDocument // Property 'field' does not exist on type 'Document<unknown, any, unknown> & { _id: ObjectId; }'.ts(2339)

Expected Behavior

I would expect const MyModel = model<any>('My', MySchema); const myDocument = new MyModel({ ... }) to behave like HydratedDocument<any>.

I would expect const MyModel = model<any>('My'); const myDocument = new MyModel({ ... }) to behave like HydratedDocument<any>.

I would expect const myDocument = new MyModel<any>({ field: 'a' }) to behave like HydratedDocument<any>.

[IslandRhythms]

import { Schema } from 'mongoose'

const MySchema = new Schema({
  field: { type: String }
})

import { model } from 'mongoose'
/*
const MyModel = model('My', MySchema)

const myDocument = new MyModel({ field: 'a' })
const { field } = myDocument
*/

const MyModel = model<any>('My', MySchema)

const myDocument = new MyModel({ field: 'a' })
const { field } = myDocument // Property 'field' does not exist on type 'Document<unknown, any, unknown> & { _id: ObjectId; }'.ts(2339)