How do you perform CRUD operations and add query methods to a Mongoose model in NestJS?

Q: How do you perform CRUD operations and add query methods to a Mongoose model in NestJS?

@Injectable() export class UsersService { constructor( @InjectModel(User.name) private readonly userModel: Model , ) {} // Create create(dto: CreateUserDto): Promise { return new this.userModel(dto).save(); } // Read all with sorting findAll(): Promise { return this.userModel.find().sort({ createdAt: -1 }).exec(); } // Read one by ID findById(id: string): Promise { return this.userModel.findById(id).exec(); } // Update — new: true returns the updated document update(id: string, dto: UpdateUserDto): Promise { return this.userModel .findByIdAndUpdate(id, dto, { new: true }) .exec(); } // Delete delete(id: string): Promise { return this.userModel.findByIdAndDelete(id).exec(); } // Populate references findWithPosts(id: string): Promise { return this.userModel.findById(id).populate('posts').exec(); } // Aggregation pipeline countByStatus(): Promise { return this.userModel.aggregate([ { $group: { _id: '$status', count: { $sum: 1 } } }, ]).exec(); } } Always call .exec() on Mongoose queries to get a true Promise instead of a thenable. findByIdAndUpdate() with { new: true } returns the updated document — without it returns the original. populate() resolves ObjectId references to full documents — use it only when the related data is needed. aggregate() returns plain objects, not Mongoose documents — no virtuals or instance methods. Use lean() on read-heavy queries to return plain JS objects instead of Mongoose documents for better performance.

Difficulty: 5/10

CRUD with Mongoose, Custom query methods, NestJS service integration

Use new this.model(dto).save() for creates, find()/findById() for reads, findByIdAndUpdate() with { new: true } for updates, and findByIdAndDelete() for deletes. Use populate() for reference resolution and aggregate() for complex aggregation pipelines.

CRUD operations with Mongoose model

Mongoose operation notes:

1
Always call .exec() on Mongoose queries to get a true Promise instead of a thenable.
2

How do you perform CRUD operations and add query methods to a Mongoose model in NestJS?

Difficulty: 5/10

CRUD with Mongoose, Custom query methods, NestJS service integration

Use new this.model(dto).save() for creates, find()/findById() for reads, findByIdAndUpdate() with { new: true } for updates, and findByIdAndDelete() for deletes. Use populate() for reference resolution and aggregate() for complex aggregation pipelines.

CRUD operations with Mongoose model

Mongoose operation notes:

1
Always call .exec() on Mongoose queries to get a true Promise instead of a thenable.
2

How do you perform CRUD operations and add query methods to a Mongoose model in NestJS?

Use new this.model(dto).save() for creates, find()/findById() for reads, findByIdAndUpdate() with { new: true } for updates, and findByIdAndDelete() for deletes. Use populate() for reference resolution and aggregate() for complex aggregation pipelines.

How do you perform CRUD operations and add query methods to a Mongoose model in NestJS?

Use new this.model(dto).save() for creates, find()/findById() for reads, findByIdAndUpdate() with { new: true } for updates, and findByIdAndDelete() for deletes. Use populate() for reference resolution and aggregate() for complex aggregation pipelines.

Scenario Questions

Follow-up Questions