Choosing the Right ORM for Your NestJS Application

Overview of ORMs

Sequelize

import { Sequelize } from 'sequelize';

const sequelize = new Sequelize('database', 'username', 'password', {
  host: 'localhost',
  dialect: 'mysql',
});

const User = sequelize.define('User', {
  name: {
    type: Sequelize.STRING,
  },
  email: {
    type: Sequelize.STRING,
    unique: true,
  },
});

(async () => {
  await sequelize.sync({ force: true });
  await User.create({ name: 'Alice', email: 'alice@example.com' });
})();

TypeORM

import { Entity, Column, PrimaryGeneratedColumn } from 'typeorm';

@Entity()
export class User {
  @PrimaryGeneratedColumn()
  id: number;

  @Column()
  name: string;

  @Column()
  email: string;
}

MikroORM

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

@Entity()
export class User {
  @PrimaryKey()
  id!: number;

  @Property()
  name!: string;

  @Property()
  email!: string;
}

Prisma

// schema.prisma
model User {
  id       Int     @id @default(autoincrement())
  name     String
  email    String  @unique
}

import { PrismaClient } from '@prisma/client';

const prisma = new PrismaClient();
async () => {
  await prisma.user.create({
    data: { name: 'Bob', email: 'bob@example.com' },
  });
};

Deep Dive: Features, Pros, and Cons

Sequelize

• Multi-Database Support: PostgreSQL, MySQL, SQLite, MariaDB, MSSQL.
• Active Record Pattern: Models handle both data and business logic.
• Extras: Transaction support, associations, migrations, and raw query support.

• Mature and Stable: Widely used with a proven track record.
• Ease of Use: Intuitive API for basic CRUD operations.
• Rich Documentation: Extensive guides and community examples.
• Migration System: Built-in CLI for schema management.

• Pattern Limitation: Only supports Active Record, which may not suit complex applications preferring separation of concerns.
• No NoSQL: Limited to SQL databases.
• Verbosity: Complex queries or large schemas can become cumbersome.
• TypeScript Support: Functional but less seamless than TypeScript-first ORMs.

TypeORM

• Broad Database Support: PostgreSQL, MySQL, SQLite, MongoDB, and more.
• Dual Patterns: Supports both Active Record and Data Mapper.
• Advanced Tools: Entity manager, connection pooling, query caching, migrations.

• Flexibility: Choose between Active Record and Data Mapper based on needs.
• TypeScript-Friendly: Strong integration with decorators.
• NoSQL Support: MongoDB compatibility expands its use cases.
• Feature-Rich: Offers caching, lazy relations, and more.

• Learning Curve: Abundance of features can overwhelm beginners.
• Complex Queries: Some users report issues with intricate relationships.
• Documentation: Comprehensive but dense for newcomers.

MikroORM

• Database Support: PostgreSQL, MySQL, SQLite, MongoDB.
• Data Mapper Pattern: Emphasizes separation of concerns.
• TypeScript-Centric: Built-in identity map, unit of work, query builder.

• Type Safety: Designed for TypeScript, minimizing runtime errors.
• Performance: Optimized with features like identity map.
• Transactional Support: Robust unit of work pattern.
• Modern Design: Aligns with current development practices.

• Smaller Community: Fewer resources compared to Sequelize or TypeORM.
• Boilerplate: May require more setup for certain tasks.

Prisma

• Database Support: PostgreSQL, MySQL, SQLite (MongoDB in preview).
• Schema-Driven: Unique DSL for defining models and relations.
• Tooling: Strongly typed client, Prisma Studio for visualization.

• Modern Workflow: Schema-first approach with type generation.
• Query Power: Excels at complex relationships and joins.
• Developer Experience: Excellent IDE integration and tooling.
• Incremental Adoption: Use alongside raw SQL if needed.

• Learning Curve: Unique paradigm requires adjustment.
• Maturity: Newer than others, with some features still evolving.
• Migration Workflow: Differs from traditional SQL migrations.

Integration with NestJS

• Sequelize: The @nestjs/sequelize package provides seamless dependency injection and module configuration.
  typescript

  import { SequelizeModule } from '@nestjs/sequelize';
  
  @Module({
    imports: [SequelizeModule.forRoot({ dialect: 'mysql', /* ... */ })],
  })
  export class AppModule {}

• TypeORM: The @nestjs/typeorm module offers tight integration.
  typescript

  import { TypeOrmModule } from '@nestjs/typeorm';
  
  @Module({
    imports: [TypeOrmModule.forRoot({ type: 'postgres', /* ... */ })],
  })
  export class AppModule {}

• MikroORM: Use @mikro-orm/nestjs for a smooth experience.
  typescript

  import { MikroOrmModule } from '@mikro-orm/nestjs';
  
  @Module({
    imports: [MikroOrmModule.forRoot({ dbName: 'my-db', /* ... */ })],
  })
  export class AppModule {}

• Prisma: Lacks a dedicated NestJS module but integrates via a custom service.
  typescript

  import { PrismaClient } from '@prisma/client';
  
  @Injectable()
  export class PrismaService extends PrismaClient {
    constructor() {
      super();
    }
  }

Migrations and Schema Management

• Sequelize: Robust CLI (sequelize-cli) for creating and running migrations.
• TypeORM: Built-in migration system with commands like typeorm migration:generate.
• MikroORM: TypeScript-based migrations with automatic schema diffing.
• Prisma: prisma migrate integrates schema changes with its DSL, offering a modern approach.

• Sequelize: Ideal for simple CRUD applications or legacy projects needing a quick setup. Best for teams comfortable with Active Record.
• TypeORM: Suits projects requiring flexibility (e.g., NoSQL support) or transitioning between patterns. Good for medium-to-large applications.
• MikroORM: Perfect for TypeScript enthusiasts prioritizing performance and Data Mapper in moderately complex apps.
• Prisma: Best for modern, type-safe projects with complex queries or a focus on developer experience.

Additional Considerations

• Sequelize: Adequate for small-to-medium apps but may lag with complex joins.
• TypeORM: Generally efficient, though heavy relations can impact speed.
• MikroORM: Optimized with identity map, often outperforming others in benchmarks.
• Prisma: Strong for complex queries but may require tuning for high-load scenarios.

• Sequelize & TypeORM: Large communities with abundant plugins and tutorials.
• MikroORM & Prisma: Growing ecosystems with active development and increasing resources.

• Sequelize: Easiest for beginners or JavaScript developers.
• TypeORM & MikroORM: Moderate, with TypeScript knowledge recommended.
• Prisma: Steeper due to its unique DSL but rewarding with mastery.

Comparison Table