How do I manage relations in TypeORM with Node.js?

How do I manage relations in TypeORM with Node.js?

In TypeORM, you can manage relations using decorators like @OneToMany, @ManyToOne, and @ManyToMany. Would you like an example?

Yes, please provide an example of a one-to-many relationship.

Sure! For a one-to-many relationship, you can define two entities. For example, a User entity and a Post entity. The User can have many Posts. Here's how you can set it up:

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

    @OneToMany(() => Post, post => post.user)
    posts: Post[];
}

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

    @ManyToOne(() => User, user => user.posts)
    user: User;
}

What if I want to add a many-to-many relationship?

For a many-to-many relationship, you can use a join table. For example, if you have Users and Groups, you can set it up like this:

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

    @ManyToMany(() => Group)
    @JoinTable()
    groups: Group[];
}

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

    @ManyToMany(() => User, user => user.groups)
    users: User[];
}