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firebase键值返回undefined

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我正在尝试使用删除按钮显示事件列表，并且只能由事件创建者删除 . 但是当我尝试删除它时，它会删除所有其他事件 . 我实际上是试图通过firebase-realtime-database中的Key Value删除，但是 event.id 返回为undefined，我猜它会删除整个文件夹 .

我的home.html，显示数据，可以直接从这个页面删除

<ion-card *ngFor="let event of eventList$ | async">
  <ion-item>
    <h4>{{event.name}}</h4>
  </ion-item>

  <ion-item>
    <h4>{{event.location}}</h4>

    <ion-buttons end>
      <button ion-button icon-only (click)="checkUser(event)">
        <ion-icon name="trash"></ion-icon>
      </button>
  </ion-buttons>
  </ion-item>

</ion-card>

我的家

this.database.list<EventModels>('event-list').valueChanges().subscribe((eventData) => { 

  }, (err)=>{
 console.log("Error while retrieving event details : ", err);
  }); 

  this.eventListRef$ = this.database.list<EventModels>('event-list');
  this.eventList$ = this.eventListRef$.valueChanges();

checkUser(event: EventModels) {
  console.log(event.id, event.name);
  if(firebase.auth().currentUser.email == event.creator) {
    let alert = this.alertCtrl.create({
      title: 'Confirm Delete.',
      message: 'You cannot recover this event once it is deleted.',
      buttons: [
        {
          text: 'Yes',
          role: 'destructive',
          handler: () => {
            this.eventListRef$.remove(event.id);
          }
        },
        {
          text: 'Cancel',
          role: 'cancel'
        }
      ]
    }).present();
  } else{
    let alert = this.alertCtrl.create({
      title: 'Could Not Delete Event!',
      subTitle: 'This event does not belong to you.',
      buttons: ['Dismiss']
    });
    alert.present();
  }
}

我在模型文件夹中的EventModels，events.ts

export interface EventModels {
  id?: string;
  creator: any;
  name: string;
  location: string;
  start: any;
  end: any;
  time: any;
}

我曾尝试使用 $key?: String 但它仍然返回undefined

创建活动

addEvent = {} as EventModels;
eventRef$: AngularFireList<EventModels>;

  this.eventRef$ = this.database.list('event-list');

  save(addEvent: EventModels){
    this.eventRef$.push({
      creator: firebase.auth().currentUser.email,
      name: this.addEvent.name,
      location: this.addEvent.location,
      start: this.addEvent.start,
      end: this.addEvent.end,
      time: this.addEvent.time,
    });

    this.addEvent = {} as EventModels;

    this.navCtrl.pop()
  }
typescript firebase ionic-framework firebase-realtime-database

1 回答

  • 1

    尝试更改 home.ts 中 eventList$ 的创建方式，而不是使用snapshotChanges()来提取每个项目的 key 并分配给 id 属性：

    // ...

import { map } from 'rxjs/operators';

// ...

this.eventListRef$ = this.database.list<EventModels>('event-list');
this.eventList$ = this.eventListRef$.snapshotChanges()
  .pipe(
    map(changes => 
      changes.map(c => ({ id: c.payload.key, ...c.payload.val() }))
    )
  );

    看起来 id 可能不是 event-list RTDB节点中每个子节点存在的属性 . snapshotChanges() 为每个对象公开元数据（如 key ）以及可用于为每个项目创建完整 EventModels 对象的对象值 .

    希望这有帮助！

    回复于

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