如何从AngularFire2中的列表中检索特定值

import { AngularFireModule } from 'angularfire2';
import { AngularFireDatabaseModule } from 'angularfire2/database';

// ...

@NgModule({
  imports: [
    AngularFireModule.initializeApp(firebaseConfig),
    AngularFireDatabaseModule
    // ...
  ],
  // ...
})

export const firebaseConfig = {
  apiKey: 'YOUR_API_KEY',
  authDomain: 'YOUR_AUTH_DOMAIN',
  databaseURL: 'YOUR_DATABASE_URL',
  projectId: 'YOUR_PROJECT_ID',
  storageBucket: 'YOUR_STORAGE_BUCKET',
  messagingSenderId: 'YOUR_MESSAGING_SENDER_ID'
};

import { AngularFireDatabase } from 'angularfire2/database';

// ...

export class MyComponent {
  items: AngularFireList<any>;

  constructor(private db: AngularFireDatabase) {
    this.items = db.list('/items');
  }

  retrieveSpecificValue(specificValue: string) {
    this.items.snapshotChanges().subscribe(actions => {
      actions.forEach(action => {
        const item = action.payload.val();
        if (item && item.property === specificValue) {
          // 找到匹配的特定值
          console.log(item);
        }
      });
    });
  }
}