您可以自行参考您的关系.这是一个简单的有向图示例(也就是一个节点可以有一个父节点和多个子节点).

You can self-reference your relations. Here is an example of a simple directed graph (aka a node can have a parent and multiple children).

@Entity()
export class Service extends BaseEntity {

  @PrimaryGeneratedColumn()
  id: number;
  
  @Column()
  @Index({ unique: true })
  title: string;

  @ManyToOne(type => Service, service => service.children)
  parent: Service;

  @OneToMany(type => Service, service => service.parent)
  children: Service[];
}

要记住的一个重要注意事项是，当使用 find* 函数从数据库读取对象时，这些关系不会自动加载.

An important note to keep in mind is that these relations are not auto loaded when reading an object from the DB with find* functions.

要实际加载它们，您现在必须使用查询构建器并加入它们.(您可以加入多个级别.)示例:

To actually load them, you have to use query builder at the moment and join them. (You can join multiple levels.) An example:

let allServices = await this.repository.createQueryBuilder('category')
  .andWhere('category.price IS NULL')
  .innerJoinAndSelect('category.children', 'product')
  .leftJoinAndSelect('product.children', 'addon')
  .getMany();

请注意我如何使用不同的名称来引用它们(category、product 和 addon).

Please note how I used different names to reference them (category, product, and addon).