A many-to-many relationship

In this lesson, we’ll learn how to manage many-to-many relationships using TypeORM.

A many-to-many relationship is typical when dealing with complex data structures. Below is an example of the user and role entities. A user entity can have multiple roles to define their access, and a role entity can be assigned to multiple users.

TypeScript 4.9.5

// user.entity.ts
@Entity('user')
export class UserEntity {
  @PrimaryGeneratedColumn()
  id: number;
    ...
  @ManyToMany(() => RoleEntity, (role) => role.users, {
    eager: true,
    cascade: ['insert', 'update'],
  })
  @JoinTable()
  roles: RoleEntity[];
}
// role.entity.ts
@Entity('role')
export class RoleEntity {
  @PrimaryGeneratedColumn()
  id: number;
  @Column()
  name: string;
  @ManyToMany(() => UserEntity, user => user.roles,  {
    cascade: ['insert', 'update'],
  })
  users: UserEntity[];
}

1.Introduction

2.NestJS Fundamentals

3.Connecting with REST: Building the Address Book App with NestJS

Assessment

4.Validation, Exception Handling, and Logging

5.Persist Data with TypeORM and MySQL

6.Serialization and Interceptors

7.Authentication and Authorization

Assessment

8.Testing

9.Deployment

Assessment

10.Conclusion

11.Appendix

Handling Many-to-Many Relationships

A many-to-many relationship

Define the entities