AngularFireList 不可分配给类型"可观察"<Response>

Question

我有一个Ionic页面，它正在查询FirebaseListObservable，以便在ion-searchbar上进行动态搜索。它适用于 Angularfire2@4.0.0-rc.0 和 firebase@4.5.0。升级新版本AngularFire 5.0后，我遇到了有关FirabaseListObservable的问题，没有从新API导出。

import { Component } from '@angular/core';
import { IonicPage,  NavParams, ViewController } from 'ionic-angular';
import {AngularFireDatabase, FirebaseListObservable} from 'angularfire2/database';
import { Observable} from 'rxjs';
import { Response } from '@angular/http';
@IonicPage()
@Component({
  selector: 'page-modal-groups',
  templateUrl: 'modal-groups.html'
})
export class ModalGroupsPage {
  groups: FirebaseListObservable<any>;
  constructor(public navParams: NavParams,
    public viewCtrl:ViewController,
    public afDatabase: AngularFireDatabase) {
  }
  getItems = (ev: any) : Observable<Response> =>  {
    
    this.groups =  this.afDatabase.list('/Groups', {
       query:{
         orderByChild: 'namelower',
         startAt: (ev.target.value),
         endAt: (ev.target.value + 'uf8ff')
       }
      }
     );
     return this.groups;
  }
  chooseGroups(item:any){
      
    this.viewCtrl.dismiss(item); 
    // console.log(this.product);
  }
  closeModal(){
    this.viewCtrl.dismiss(); 
  }
}

<ion-header>
  <ion-navbar>
    <ion-title>Grup Seç</ion-title>
    <ion-buttons end>
      <button ion-button color="danger" (click)="closeModal()" >
        Kapat
      </button>
    </ion-buttons>
  </ion-navbar>
</ion-header>
  <ion-content padding>
  <ion-searchbar (ionInput)="getItems($event)"></ion-searchbar>
  <ion-list>
    <ion-item  *ngFor="let item of groups | async" (click)="chooseGroups(item)">
      {{ item.name }}
    </ion-item>
  </ion-list>
  <!--<button ion-item  *ngFor="let item of products | async" (click)="chooseProduct(item)">
  {{item.name}}
</button>-->
</ion-content>

然后我用新的 api 更改了查询，但我无法将响应作为可观察对象返回，如下所示。我收到这样的错误

**消息："类型'可观察[]>'不可分配给类型'可观察'。 类型"AngularFireAction[]"不能分配给类型"响应"。 属性"type"在类型"AngularFireAction[]"中缺失。**

import { Component } from '@angular/core';
import { IonicPage,  NavParams, ViewController } from 'ionic-angular';
import {AngularFireDatabase, AngularFireAction} from 'angularfire2/database';
import { Observable, BehaviorSubject} from 'rxjs';
import { Response } from '@angular/http';
/**
 * Generated class for the ModalGroupsPage page.
 *
 * See http://ionicframework.com/docs/components/#navigation for more info
 * on Ionic pages and navigation.
 */
@IonicPage()
@Component({
  selector: 'page-modal-groups',
  templateUrl: 'modal-groups.html',
})
export class ModalGroupsPage {
  
  items: Observable<AngularFireAction<firebase.database.DataSnapshot>[]>;
  group: BehaviorSubject<any>;
  constructor(public navParams: NavParams,
    public viewCtrl:ViewController,
    public afDatabase: AngularFireDatabase) {
  }
  
  getItems = (ev: any) : Observable<Response> =>  {
    this.group = new BehaviorSubject(ev);
    this.items = this.group.switchMap(name =>
    
      this.afDatabase.list('/Groups', ref => name ? ref.orderByChild('namelower').startAt(ev.target.value).endAt(ev.target.value + 'uf8ff') : ref
   
     ).snapshotChanges());
  
     return this.items;
  }

Answer 1

为了从 5.0 开始从 AngularFireList 获得Observable<Response>，使用valueChanges()功能。

在此处查看更改。

return this.afDatabase.list('/Groups', {
       query:{
         orderByChild: 'namelower',
         startAt: (ev.target.value),
         endAt: (ev.target.value + 'uf8ff')
       }
      }
     ).valueChanges();

如果要在 this.groups 中保存 this.afDatabase.list() 的实例，它将AngularFireList而不是FirebaseListObservable。

Answer 2

您需要使用如下所示的.valueChanges()。这是文档。

  groups: AngularFireList<any>;
  constructor(){}
getItems = (ev: any) : AngularFireList<any> {
  this.groups =  this.afDatabase.list('/Groups', {
       query:{
         orderByChild: 'namelower',
         startAt: (ev.target.value),
         endAt: (ev.target.value + 'uf8ff')
       }
      }
     ).valueChanges();
    return this.groups;
}

Answer 3

Angular 5.0 是 AngularFireDatabase 的重构，它删除了 FirebaseListObservable 和 FirebaseObjectObservable

FirebaseListObservable ====> AngularFireListFirebaseObjectObservable====>AngularFireObject

您可以点击链接

Answer 4

在 Angularfire2 5.0 或更高版本中，如果您需要带有查询的可观察列表，则必须使用 AngularFireAction，如下所示

import { Component } from '@angular/core';
import { IonicPage, NavParams, ViewController} from 'ionic-angular';
import {AngularFireDatabase, AngularFireAction} from 'angularfire2/database';
import { Observable } from 'rxjs/Observable';
import {EmptyObservable} from 'rxjs/observable/EmptyObservable';
// import { Response } from '@angular/http';
import * as firebase from 'firebase/app';
@IonicPage()
@Component({
  selector: 'page-modal-groups',
  templateUrl: 'modal-groups.html',
})
export class ModalGroupsPage {
  
  groups: Observable<AngularFireAction<firebase.database.DataSnapshot>[]>;
  
  constructor(public navParams: NavParams,
    public viewCtrl:ViewController,
    public afDatabase: AngularFireDatabase) {
  }
 -
  getItems = (ev: any) : Observable<AngularFireAction<firebase.database.DataSnapshot>[]> => {
    if(!ev.data){
      return this.groups = new EmptyObservable();
    }
    this.groups =  this.afDatabase.list('/Groups', ref => ref.orderByChild('namelower').startAt(ev.target.value).endAt(ev.target.value + 'uf8ff')).valueChanges();
    // this.groups = this.groupsRef.valueChanges();
      return this.groups;
  }
  chooseGroups(item:any){
    // this.product.push({key:item.$key, name:item.name, price:item.price, quantity:1 });
      
    this.viewCtrl.dismiss(item); 
    // console.log(this.product);
  }
  closeModal(){
    this.viewCtrl.dismiss(); 
  }
}

Answer 5

我安装了以下版本的 angularfire2 和 Firebase：

npm install  angularfire2@4.0.0-rc0 firebase --save