class BaseService<Models> {
  
  public m: Models;

  constructor(model: Models) {
    this.m = model;
  }
}


class MyService extends BaseService<UserModel>{
  
  constructor() {
    super(UserModel);  //It is require new keyword
  }

}

We are using knex.js with Objection.js models. I'm able to run queries in MyService class. e.g.

const user = await UserModel.query().findById(1);

But instead i want a base service that to set Model using generic type.

What i need from child class id.

super(UserModel);  //It is not working

If i pass UserModel using new keyword then error removed but queries not working

super(new UserModel())

CodePudding user response：

Typescript Playground Link

You tried to pass class to super class, but it expected instance of that class

class BaseService<Models> {
  
  public m: Models;

  constructor(model: Models) {
    this.m = model;
  }
}

class UserModel {}

class MyService extends BaseService<typeof UserModel>{
  
  constructor() {
    super(UserModel);  //It is require new keyword
  }

}

new MyService();