Question

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。我实际上是在尝试从Firebase-realtime-database中通过键值删除，但是event.id返回未定义，我想它会删除整个文件夹。

我的home.html，显示数据，可以直接从此页面删除

<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home.ts

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();
  }
}

我的EventModels，models文件夹中的events.ts

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

我尝试使用$key?: String，但仍返回未定义

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()
  }

Answer 1

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

// ...

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() }))
    )
  );

id可能不是您的event-list RTDB节点中每个孩子都拥有的属性。 snapshotChanges()公开每个对象的元数据，例如key以及可用于为每个项目创建完整的EventModels对象的对象值。

希望有帮助！

firebase键值返回未定义

1 个答案: