useful typeorm base entities

README.md

Useful base entities for TypeORM

Attribute

Any database entity. Attributes are usually being used as a child for an Existence or a Reflection.

Existence

Entities that can be changed or deleted in time.

Reflection

Entities that has an equivalent in the real world. Not only these entities reflect a real life being like an object, or a person also abstract things like posts or comments.

attribute.ts

import { BaseEntity, PrimaryGeneratedColumn, SaveOptions } from "typeorm";

export abstract class Attribute extends BaseEntity {
  @PrimaryGeneratedColumn()
  id: number;

  save(options?: SaveOptions): Promise<this> {
    return super.save(options);
  }
}

existence.ts

import {
  AfterInsert,
  AfterLoad,
  AfterUpdate,
  Column,
  CreateDateColumn,
  DeleteDateColumn,
  UpdateDateColumn
} from "typeorm";
import { Attribute } from "../attribute/attribute";

const DELETED_AT = Symbol("Existence.deletedAt");

export abstract class Existence extends Attribute {
  @CreateDateColumn()
  createdAt: Date;

  @UpdateDateColumn()
  updatedAt: Date;

  @DeleteDateColumn()
  deletedAt?: Date;

  // to support duplicate unique entities
  // when the old one is deleted
  // @Index(['username', 'deletedAtMS'], { unique: true })
  @Column()
  deletedAtMS = 0;

  @AfterLoad()
  async onRead(): Promise<void> {
    this[DELETED_AT] = this.deletedAt;
  }

  @AfterUpdate()
  @AfterInsert()
  async onWrite(): Promise<void> {
    if (this.deletedAt !== this[DELETED_AT]) {
      this.deletedAtMS = Date.now();
      await this.save();
    }
  }
}

reflection.ts

import { Column } from "typeorm";
import { Existence } from "../existence/existence";

export abstract class Reflection extends Existence {
  @Column()
  displayName: string;

  @Column()
  description?: string;
}