Node.js and sequelize-typescript - data access objects and business objects - node.js

Question

I am using the sequelize-typescript in my Node.js service
I have the Category class which maps to category table
import { Model, Table, Column } from "sequelize-typescript";
#Table
export class Category extends Model<Category>{
#Column
name: string
}
I also have CategoryController and CategoryService
export class CategoryController {
...
async getAll(request: Request, response: Response) {
let categories = await this.categoryService.getCatergories();
response.json(categories)
}
}
export class CategoryService {
async getCatergories(): Promise<Category[]> {
let categories = await Category.findAll<Category>()
return categories
}
}
And everything is as it should be.
But returning a Category to the controller allows it to use the use the inherited methods from the model class like:
export class CategoryController {
...
async getAll(request: Request, response: Response) {
let categories = await this.categoryService.getCatergories();
// Remove associated row in the database
categories[0].destroy()
response.json(categories)
}
}
I was thinking to create a CategoryModel class like this:
export class CategoryModel {
id : number
name : string
}
And modify all methods in CategoryService to return CategoryModel instances instead of Category and rename Category to CategoryEntity
What is the best way to deal with such a problem?

Answer 1

Use toJSON() of Category instance to get "a JSON representation" of the instance.
See sequelize docs for more information: http://docs.sequelizejs.com/class/lib/model.js~Model.html#instance-method-toJSON
Additionally you could add an interface to achieve type safety for the return value of toJSON() instead of defining another class:
interface ICategory {
id: number;
name: string;
}
#Table
export class Category extends Model<Category> implements ICategory{
#Column
name: string
}
Using toJSON():
Category.findOne(result => {
const category: ICategory = result.toJSON();
});