なぜ「未定義」のIDがangular2で送信された後に変更されたのですか？

Question

私は、コンポーネント内のfolowing方法があります：サービスで

onSubmit() { 
    this.isLoading = true; 
    const successCallback = (result) => { 
     this.isLoading = false; 
     if (result) { 
      this.notificationId = result.Id; 
     } 
     this.router.navigate(['../' + this.notificationId], { relativeTo: this.route }); 
    }; 

    if (this.isNew) { 
     this.dataService.create(this.model).then(successCallback); 
    } else { 
     this.dataService.update(this.model).then(successCallback); 
    } 
} 

ngOnInit(): void { 
    this.isLoading = true; 
    this.notificationId = parseInt(this.route.snapshot.params['notificationid'], 10); 
    this.projectId = parseInt(this.route.snapshot.params['projectid'], 10); 
    let loadTask: Promise<NotificationOfParticipationViewModel>; 

    if (this.notificationId == 0) { 
     loadTask = Promise.resolve(new NotificationOfParticipationViewModel()); 
    } else { 
     loadTask = this.dataService.getById(this.notificationId); 
    } 

    loadTask.then(result => { 
     this.model = Object.assign(new NotificationOfParticipationViewModel(), result); 
     this.isLoading = false; 
    }); 
} 

を：

update(notification: NotificationOfParticipationViewModel): Promise<any> { 
    return this.baseService.put(this.apiUrl, notification); 
} 

create(signatory: NotificationOfParticipationViewModel): Promise<NotificationOfParticipationViewModel> { 
    return this.baseService.post(this.apiUrl, signatory); 
} 

Serverのいくつかの計算は、後に提出ありません。 26がundefinedに変更し、なぜ私は、理解していない

http://localhost:55077/projects/2/notificationsofparticipation/undefined 

：？

前URLは次のようになり提出：

http://localhost:55077/projects/2/notificationsofparticipation/26 

しかし、後のURLは次のようになり提出

Answer 1

 onSubmit() { 
      this.isLoading = true; 
      const successCallback = (result) => { 
       this.isLoading = false; 
       if (result && result.hasOwnProperty("Id")) { 
        this.notificationId = result.Id; 
       }else{ 
        console.log("ID not present in result obj"); 
       } 
       this.router.navigate(['../' + this.notificationId], { relativeTo: this.route }); 
      }; 

      if (this.isNew) { 
       this.dataService.create(this.model).then(successCallback); 
      } else { 
       this.dataService.update(this.model).then(successCallback); 
      } 
     }