使用 TypeORM 保存实体时出现 CannotDetermineEntityError

Question

我创建了一个 NestJS 并使用 TypeORM 作为 RDBMS（我在项目中使用了 postgres）。

Post是一个@Entity类，PostRepository是 的一个Repository类Post。

我试图创建OnModuleInit服务来初始化一些数据。

@Injectable()
export class PostsDataInitializer implements OnModuleInit {
  private data: Post[] = [
    {
      title: 'Generate a NestJS project',
      content: 'content',
    },
    {
      title: 'Create GrapQL APIs',
      content: 'content',
    },
    {
      title: 'Connect to Postgres via TypeORM',
      content: 'content',
    },
  ];

  constructor(private readonly postRepository: PostRepository) {}
  async onModuleInit(): Promise<void> {
    await this.postRepository.manager.transaction(async (manager) => {
      // NOTE: you must perform all database operations using the given manager instance
      // it's a special instance of EntityManager working with this transaction
      // and don't forget to await things here
      await manager.delete(Post, {});
      console.log('deleted: {} ');
      this.data.forEach(async (d) => await manager.save(d as Post));
      const savedPosts = await manager.find<Post>(Post);
      savedPosts.forEach((p) => {
        console.log('saved: {}', p);
      });
    });
  }
}

启动应用程序时，我收到以下错误。

CannotDetermineEntityError: Cannot save, given value must be instance of entity class, instead object literal is given. Or you must specify an entity target to method call.

但上面save正在接受 的一个实例Post。

Answer 1

我认为这几乎就是错误所说的。您不能将文字对象传递给.save

  private data = [
    {
      title: 'Generate a NestJS project',
      content: 'content',
    },
    {
      title: 'Create GrapQL APIs',
      content: 'content',
    },
    {
      title: 'Connect to Postgres via TypeORM',
      content: 'content',
    },
  ].map(data => {
    const post = new Post();
    Object.assign(post, data);
    return post;
  })

以上可能会解决这个问题。

Answer 2

您也可以根据错误消息指定目标类型，如下所示：

await manager.save(Post, d)

从 save() 的文档中我看到有这样的方法：

save<Entity, T extends DeepPartial<Entity>>(targetOrEntity: EntityTarget<Entity>, entity: T, options?: SaveOptions): Promise<T & Entity>;

巢版本9.1.8