Mongodb: insert and update generics example

index.ts

import { Collection, Db } from 'mongodb'

interface IEntity {
  field: string
}

interface IUpdate<T> {
  $set: T
}

class MongoDB {
  public db: Db;

  public collection(): Collection<IEntity> {
      return this.db.collection('collection');
  }
}

const db = new MongoDB()

// This generics definition will allow us to check if a type of an incoming DTO matches our model
// I understand that MongoB is schemaless by default, but usually we still want to ensure some ind of schema
interface IDTO {
  field: string
}
// without generics
async function ctrl (dto: DTO) {
  const doc: IEntity = dto
  await db.collection().insertOne(doc)
}
// with generics
async function ctrlNew (dto: DTO) {
  await db.collection().insertOne<IEntity>(dto)
}
  
  
const res1 = db.collection().insertOne<IEntity>({field: 'a'})
const res1a = db.collection().insertOne({})
const res2 = db.collection().insertMany<IEntity>([{field: 'a'}])
const res2a = db.collection().insertMany([{}])
const res3 = db.collection().updateOne<IUpdate<IEntity>>({}, {$set: {field: 'a'}})
const res3a = db.collection().updateOne({}, {})
const res4 = db.collection().updateMany<IUpdate<IEntity>>({}, {$set: {field: 'a'}})
const res4a = db.collection().updateMany({}, {})