nest-data-layer

NestJS Data Layer

This skill consolidates ORM patterns for the three most common choices in NestJS projects: TypeORM, Prisma, Mongoose. Detect which is in use, then apply the matching section.

Detection

TypeORM

Module setup

// src/app.module.ts
@Module({
  imports: [
    TypeOrmModule.forRootAsync({
      imports: [ConfigModule],
      inject: [ConfigService],
      useFactory: (config: ConfigService) => ({
        type: 'postgres',
        url: config.get<string>('DATABASE_URL'),
        autoLoadEntities: true,
        synchronize: false,                 // NEVER true in prod — use migrations
        migrations: ['dist/migrations/*.js'],
        migrationsRun: false,
        logging: config.get<string>('NODE_ENV') !== 'production',
      }),
    }),
  ],
})

Entity

// src/users/entities/user.entity.ts
import { Entity, PrimaryGeneratedColumn, Column, CreateDateColumn, UpdateDateColumn, Index, OneToMany } from 'typeorm';

@Entity('users')
export class User {
  @PrimaryGeneratedColumn('uuid')
  id!: string;

  @Index({ unique: true })
  @Column({ length: 255 })
  email!: string;

  @Column({ select: false })            // hash never selected by default
  passwordHash!: string;

  @Column({ type: 'jsonb', default: {} })
  metadata!: Record<string, unknown>;

  @CreateDateColumn()
  createdAt!: Date;

  @UpdateDateColumn()
  updatedAt!: Date;

  @OneToMany(() => Order, (order) => order.user)
  orders!: Order[];
}

• select: false for sensitive columns (passwords, tokens) — must explicitly .addSelect('user.passwordHash').
• @Index({ unique: true }) instead of @Column({ unique: true }) for clarity at index level.
• Use relations array on find options (not eager: true) — eager loading is hard to opt out of later.