Discussion on: How can I reduce amount of boilerplate code while working with TypeScript+mongoose 🙈

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Replies for: You could do type Entity<T> = T & { id: string; createdAt: Date; } // and use it like this: const vehicle: Entity<VehicleOw...

Ok, this is good one. Thank you.
How can I optimize other fields?

I'm on mobile at the moment. I'll post some other suggestions in a bit when I'm back at my laptop. On general though, union types and generics really help with these kinds of situations to make types more maintainable.

Nick Taylor • Feb 28 '19 • Edited

From there you could even do a Mongoose document generic type.

type Entity<T> = T & {
    id: string;
    createdAt: Date;
}

interface Vehicle {
    model: string;
    year?: string;
    seatsCount?: number;
}

type MongooseDocument<T> = T & mongoose.Document

const dbDocument: MongooseDocument<Entity<Vehicle>> = {
    SomeMongooseDocProperty: 'yolo',
    createdAt: new Date(),
    id: '5FCA1C32-1D92-47CA-A885-A5A747E6E4FB',
    model: 'Mini',
    seatsCount: 4,
    year: '1999'
}

You could refine this more if you wanted to make a Vehicle type which just wraps the Entity<T>.

You can see it in action in the enhanced TypeScript playground.

Also, this might interest you.

An Enhanced TypeScript Playground

Nick Taylor

#githunt#typescript

Konstantin Alikhanov • Feb 28 '19

Ok, I will play with it. Thank you.

Nick Taylor • Mar 1 '19

You can even go a bit further.

interface BaseEntity {
  id: string;
  createdAt: Date;
}

type Entity<T> = T & BaseEntity;

interface Vehicle {
  model: string;
  year?: string;
  seatsCount?: number;
}

// Enforce having the bare minimum entity properties
type MongooseDocument<T extends BaseEntity> = T & mongoose.Document;

const dbDocument: MongooseDocument<Entity<Vehicle>> = {
  SomeMongooseDocProperty: "yolo",
  createdAt: new Date(),
  id: "5FCA1C32-1D92-47CA-A885-A5A747E6E4FB",
  model: "Mini",
  seatsCount: 4,
  year: "1999"
};

See the updated playground example