Features
- Unit of Work pattern for automatic change tracking
- Identity Map prevents duplicate entity instances
- Schema-first, code-first, or entity-first approaches
- Built-in Seeder and SchemaGenerator
Pros
- Sophisticated patterns (UoW, Identity Map) from enterprise ORMs
- Excellent TypeScript support with strict type checking
- Active development with responsive maintainer
Cons
- Smaller community than Prisma or TypeORM
- Unit of Work pattern has a learning curve
- Heavier abstraction may be overkill for simple projects
Overview
MikroORM is a TypeScript ORM that implements the Unit of Work and Identity Map patterns, inspired by Doctrine (PHP) and Hibernate (Java). The Unit of Work automatically tracks entity changes and flushes them to the database in a single transaction, reducing the number of queries and ensuring consistency.
MikroORM supports PostgreSQL, MySQL, MariaDB, SQLite, and MongoDB. It offers multiple definition styles — decorators, EntitySchema, or schema-first — and integrates well with NestJS. Its strict TypeScript types catch errors at compile time rather than runtime.
When to Use
MikroORM is a strong choice for projects that benefit from Unit of Work and Identity Map patterns, for NestJS applications that need a TypeScript-native ORM with sophisticated entity management, or when migrating from Doctrine or Hibernate.
Getting Started
npm install @mikro-orm/core @mikro-orm/postgresqlimport { Entity, PrimaryKey, Property } from "@mikro-orm/core";
@Entity()
export class User {
@PrimaryKey()
id!: number;
@Property()
name!: string;
@Property({ unique: true })
email!: string;
}