MikroORM Entity Guide

Use this skill when creating or modifying MikroORM entity files (

*.entity.ts

).

Basic Entity Structure

import { Entity, PrimaryKey, Property, Unique } from '@mikro-orm/core';
import { uuidv7 } from 'uuidv7';

import { EntityEnum } from '../entity.enums';

@Entity()
export class EntityName {
  @PrimaryKey({ type: 'uuid' })
  id: string = uuidv7();

  @Property()
  @Unique()
  uniqueField!: string;

  @Property({ length: 30, nullable: true })
  optionalField?: string;

  @Property({ type: 'date', nullable: true })
  dateField?: Date;

  @Property({ type: 'string', nullable: true })
  enumField?: EntityEnum;

  @Property({ onCreate: () => new Date() })
  createdAt?: Date;

  @Property({ onCreate: () => new Date(), onUpdate: () => new Date() })
  updatedAt?: Date;
}

Core Rules

1. Primary Key

• Use UUID v7: Use

  uuidv7

  package for time-ordered UUIDs
• Assign default value directly in class field (

  = uuidv7()

  )

2. Property Decorators

• Required fields: Use

  !

  (definite assignment assertion)
• Optional fields: Use

  ?

  (optional) with

  nullable: true

  option
• String length limits: Use

  length

  option
• Date type: Explicitly specify

  { type: 'date' }

3. Enum Fields

• Use

  @Property({ type: 'string' })

• Define enums in separate

  .enums.ts

  file

4. Timestamps

• onCreate

  : Auto-set on creation

• onUpdate

  : Auto-update on modification
• Both fields declared as optional (

  ?

  )

5. Unique Constraints

• Place

  @Unique()

  decorator below

  @Property()

Enum File Structure (*.enums.ts)

export enum EntityStatus {
  ACTIVE = 'ACTIVE',
  INACTIVE = 'INACTIVE',
  DELETED = 'DELETED',
}

export enum EntityType {
  TYPE_A = 'TYPE_A',
  TYPE_B = 'TYPE_B',
}

• Values in uppercase SNAKE_CASE
• Keep key and value identical

File Naming Conventions

• Entity file:

  {entity-name}.entity.ts

• Enum file:

  {module-name}.enums.ts

• Folder structure:

  src/{module}/entities/