我有以下要保存的实体：

@Entity('approvals')
    export class Approval {
      @PrimaryGeneratedColumn()
      id: string;
    
      @ManyToOne(type => Task, task => task.approvals, {nullable: false, onDelete: 'CASCADE', lazy: true})
      task: Promise<Task> | Task;
    
      @ManyToOne(type => User, user => user.approvals, {nullable: false, onDelete: 'CASCADE', lazy: true})
      user: Promise<User> | User;
    
      @Column({ type: 'enum', enum: ApprovalState, default: ApprovalState.None })
      state: ApprovalState;
    
      constructor(partialApproval: Partial<Approval>) {
        Object.assign(this, partialApproval);
      }
    }

如果我想保存一个如下所示的实体（调试时复制）：

[
      {
        "task": {
          "id": "2",
          "name": "task1",
          "type": "type1",
          "neededTimeSeconds": 0,
          "factor": 1,
          "userId": "1",
          "periodStart": "2019-01-01",
          "periodEnd": "2019-01-31",
          "done": true,
          "__user__": {
            "id": "1",
            "username": "user1",
            "password": "$2b$10$SBPIVm9p8L4YkpiUVJ.mpedIgWi5Je6MuWTM7IvgMdyhr27JYM0OG",
            "credits": 0,
            "gravatarHash": null
          },
          "__has_user__": true
        },
        "user": {
          "id": "2",
          "username": "shouldHaveApprovalUser1",
          "password": "password1",
          "credits": 0,
          "gravatarHash": null
        }
      },
      {
        "task": {
          "id": "2",
          "name": "task1",
          "type": "type1",
          "neededTimeSeconds": 0,
          "factor": 1,
          "userId": "1",
          "periodStart": "2019-01-01",
          "periodEnd": "2019-01-31",
          "done": true,
          "__user__": {
            "id": "1",
            "username": "user1",
            "password": "$2b$10$SBPIVm9p8L4YkpiUVJ.mpedIgWi5Je6MuWTM7IvgMdyhr27JYM0OG",
            "credits": 0,
            "gravatarHash": null
          },
          "__has_user__": true
        },
        "user": {
          "id": "3",
          "username": "shouldHaveApprovalUser2",
          "password": "password1",
          "credits": 0,
          "gravatarHash": null
        }
      }
    ]

然后用上面的数组调用repository.save()，得到：

null value in column "taskId" violates not-null constraint

虽然这里明确地把id定义在每个task中。
这是Task实体类：

@Entity('tasks')
    export class Task {
      @PrimaryGeneratedColumn({ type: 'bigint' })
      id: string;
    
      @Column({ length: 30 })
      name: string;
    
      @Column({ default: 'help' })
      type: string;
    
      @Column({ name: 'needed_time', type: 'int', nullable: true })
      neededTimeSeconds: number;
    
      @Column({ type: 'int', default: 1 })
      factor: number;
    
      @ManyToOne(type => User, { nullable: true, lazy: true })
      @JoinColumn({ name: 'user_id' })
      user: Promise<User>;
    
      @Column({ name: 'user_id' })
      @RelationId((task: Task) => task.user)
      userId: string;
    
      @Column({ name: 'period_start', type: 'date', default: new Date() })
      periodStart: string;
    
      @Column({ name: 'period_end', type: 'date', default: new Date() })
      periodEnd: string;
    
      @Column({ type: 'boolean', default: false })
      done: boolean;
    
      @OneToMany(type => Approval, approval => approval.task, { nullable: true, lazy: true })
      approvals: Promise<Approval[]>;
    
      @OneToMany(type => TaskMessage, taskMessage => taskMessage.task, { cascade: ['remove'], lazy: true })
      messages: Promise<TaskMessage[]>;
    
      constructor(partialTask: Partial<Task>) {
        Object.assign(this, partialTask);
      }
    
    }

谁能告诉我为什么不分配/保存关系task？