docs(mongo): change the way to define the mongoose document interface

[arkist]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/docs.nestjs.com/blob/master/CONTRIBUTING.md

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Docs
• Other... Please describe:

What is the current behavior?

Currently, techniques/mongodb doc uses intersection type for defining the mongoose document interface.

import { Document } from 'mongoose';

export type CatDocument = Cat & Document;

it was okay before mongoose@6.3.2 but after that, they replaced the use of this with generics(T) in many Document methods so it infers incorrectly now.

// before
toObject(options?: ToObjectOptions): LeanDocument<this>;
toObject<T = DocType>(options?: ToObjectOptions): T;

// latest
toObject<T = LeanDocument<DocType>>(options?: ToObjectOptions): Require_id<T>;

// from: https://github.com/Automattic/mongoose/commit/659436de47d55aaa0a984b8f4cc99232c5ca8a16

type CatDocument = Cat & Document;

class CatsService {
  constructor(@InjectModel(Cat.name) private catModel: Model<CatDocument>) {}

  create() {
    const cat = await this.catModel.create(createCatDto);
    const catObj = cat.toObject();
    // const catObj: LeanDocument<any> & Required<{_id: unknown}>

    return catObj;
  }
}

What is the new behavior?

Mongoose introduced HydratedDocument from 6.0.13.

import { HydratedDocument } from 'mongoose';

export type CatDocument = HydratedDocument<Cat>;

defining document interface as HydratedDocument of Cat so can infer the type from Document methods correctly.

type CatDocument = HydratedDocument<Cat>;

class CatsService {
  constructor(@InjectModel(Cat.name) private catModel: Model<CatDocument>) {}

  create() {
    const cat = await this.catModel.create(createCatDto);
    const catObj = cat.toObject();
    // const catObj: LeanDocument<Cat> & {_id: Types.ObjectId}

    return catObj;
  }
}

refs:
Automattic/mongoose@8120c8f
https://github.com/Automattic/mongoose/blob/6.7.0/docs/typescript.md#creating-your-first-document

Does this PR introduce a breaking change?

• Yes
• No

[kamilmysliwiec]

Would you like to create a PR updating the corresponding sample in the nestjs/nest repository? https://github.com/nestjs/nest/blob/master/sample/06-mongoose/src/cats/schemas/cat.schema.ts

[arkist]

@kamilmysliwiec sure 😄 👉🏻 nestjs/nest#10505

[kamilmysliwiec]

lgtm