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

Konstantin Alikhanov on February 28, 2019

Let's say I have two entities: Vehicle and Tariff. They are related as 1-to-many (vehicle can has many tariffs). This is my basic types definitio...

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Nick Taylor • Feb 28 '19 • Edited

You could do

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

// and use it like this:
const vehicle: Entity<VehicleOwnFields> = ...

Leveraging generics is probably the way to go.

Konstantin Alikhanov • Feb 28 '19

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

Nick Taylor • Feb 28 '19

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

Michael De Abreu • Feb 28 '19

You could always use something like TypeORM. I haven't try it myself, as the last time I needed an ODM I used camo but I think it has been deprecated now.

Alex Sharp 🛠sharesecret.co • Mar 3 '19 • Edited

I recently found typegoose, which seems promising and seems to attempt to solve this problem. Disclaimer: I haven't used it.

I will say, I'm about a year into a codebase with typescript and mongoose, and I wish I would've just started with TypeORM, and at some point I may switch. Mongoose seems like a project that's either already dead or on life-support.

Jason C. McDonald • Mar 3 '19

How do I replace boilerplate...

Simple: Use Python!

...

Yes, I am absolutely, undeniably kidding. I've heard that joke in my head every time I read your article title, since I posted!

(Honestly, though, I know nothing about TypeScript or mongoose, so I can't make any factual or useful comparisons to Python...and anyway, even if I could, it wouldn't be useful, since you already picked the stack you need!)

Konstantin Alikhanov • Mar 3 '19

I moved to Node.JS from Python :)

Nayden Gochev • Nov 4 '19 • Edited

Hey there you can use typegoose also you can completely remove the double Model/Schema generation and even the DTOs are not required..

Example with nestjs + typegoose + mongodb :

github.com/gochev/nest-js-poc-mongodb

Nayden Gochev • Nov 5 '19

also I have added a blog post about that
dev.to/gochev/nestjs-mongo-typegoo...