Extending multiple entities IN TypeORM-NestJS

Question

Hi I don't wanted to keep adding common columns to all entity. So I'm thinking to write it on separate class and extend it to those which needs those columns. I Tried something but it is throwing " Classes can only extend a single class" Error

I don't have much hands on on TS, I'm new to TS. Can anyone help me out ?

Please find the below code:

1.Base Entity

import { Entity, PrimaryGeneratedColumn } from "typeorm";

@Entity()
export class BaseModel {
  @PrimaryGeneratedColumn("uuid")
  id: string;
}

2. Audit Entity

import { CreateDateColumn, DeleteDateColumn, Entity, UpdateDateColumn } from "typeorm";

@Entity()
export class AuditModel {
    @CreateDateColumn()
    created!: Date;

    @UpdateDateColumn()
    updated!: Date;

    @DeleteDateColumn()
    deletedAt?: Date;
}

3.User Entity

import { AuditModel } from 'src/baseModels/auditEntity';
import { BaseModel } from 'src/baseModels/baseEntity';
import {
  Entity,
  Column
} from 'typeorm';

@Entity()
export class Users extends BaseModel,AuditModel {

  @Column({ unique: true })
  email: string;

  @Column({ nullable: false })
  name: string;

  @Column({default:false})
  isActive:boolean

  @Column({ select: false })
  password: string;

}

Answer 1

Unlike other languages, JavaScript does not allow you to extend more than one class (single inheritance).

I would suggest making your AuditModel extend BaseModel:

export class AuditModel extends BaseModel {
    @CreateDateColumn()
    created!: Date;

    @UpdateDateColumn()
    updated!: Date;

    @DeleteDateColumn()
    deletedAt?: Date;
}

Then your UsersModel only has to extend the AuditModel:

@Entity()
export class Users extends AuditModel {

  @Column({ unique: true })
  email: string;

  @Column({ nullable: false })
  name: string;

  @Column({default:false})
  isActive:boolean

  @Column({ select: false })
  password: string;

}

---

Do not use @Entity on classes that won't live in your database!