使用 Angular firestore 返回 firebase 中的子集合 [英] Return a sub-collection in firebase using Angular firestore

问题描述

我有一个名为保存为每个用户的嵌套集合的子集合.用户有自己的字段和保存的集合，其中包含两个字段和一个数组.我只能显示用户字段，但我不知道访问每个用户子集合的正确方法.

 导出类 SavedComponent 实现 OnInit{公共保存:已保存[]；公共当前用户:任何=空；公共用户:用户；私人订阅:订阅[] = [];构造函数(//添加保存的服务私有的savedService:SavedService，私人身份验证:AuthService，私有加载服务:加载服务，私人路线:ActivatedRoute，私有数据库:AngularFirestore){//this.loadingService.isLoading.next(true);}this.subscriptions.push(this.auth.currentUser.subscribe( 用户 => {this.currentUser = 用户；this.loadingService.isLoading.next(false);//控制台记录当前已认证的用户控制台日志(this.currentUser)；}));this.subscriptions.push(this.route.paramMap.subscribe( params => {const userId = params.get('userId');const userRef: AngularFirestoreDocument<用户>= this.db.doc(`users/${userId}`);userRef.valueChanges().subscribe(user => this.user = user);}))//html模板示例<div class="row justify-content-center"><div class="col-xs-12 col-sm-8 col-md-6 text-center name">{{user?.firstName}} {{user?.lastName}}

解决方案

正如 Frank van Puffelen 所说，访问用户子集的最佳选择是

 this.db.collection(`users/${userId}/saved`)

要访问您保存的子集合，您需要先访问用户集合中的用户文档.根据此 Firestore 文档，访问子集合的文档，您可以交替访问集合，然后访问文档，等等以到达子集合或子集合的文档.

<块引用>

不能引用集合中的集合或文档中的文档.

为集合或子集合指定 this.db.collection ，为集合或子集合的文档指定 this.db.doc 很重要.

I have a sub-collection called saved as a nested collection to each user. User has its own fields and a collection of saved which contains two fields and an array. I can display only user fields but i don't know a proper way to access each user sub-collection.

 export class SavedComponent implements OnInit{
  public saved: Saved[];
  public currentUser: any = null;
  public user: User;
  private subscriptions: Subscription[] = [];

  constructor(

    // Adding saved service
    private savedService: SavedService,
    private auth: AuthService,
    private loadingService: LoadingService,
    private route: ActivatedRoute,
    private db: AngularFirestore
  ) {
    // this.loadingService.isLoading.next(true);
}

    this.subscriptions.push(
      this.auth.currentUser.subscribe( user => {
        this.currentUser = user;
        this.loadingService.isLoading.next(false);
        // Console log the current authentiucated user 
        console.log(this.currentUser);
      })
    );

    this.subscriptions.push(
      this.route.paramMap.subscribe( params => {
        const userId = params.get('userId');
        const userRef: AngularFirestoreDocument<User> = this.db.doc(`users/${userId}`);
        userRef.valueChanges().subscribe(user => this.user = user);
      })
    )


   // Example of html template

    <div class="row justify-content-center">
        <div class="col-xs-12 col-sm-8 col-md-6 text-center name">
            {{user?.firstName}} {{user?.lastName}}
        </div>
    </div>

解决方案

As Frank van Puffelen commented, your best bet to access a user's subcollection is

    this.db.collection(`users/${userId}/saved`)

To reach your saved subcollection, you need to first access your user document inside your users collection. As per this Firestore document, a query's structure to access a subcollection's document, you alternate between accessing a collection, then a document, and so on to reach a subcollection, or a subcollection's document.

You cannot reference a collection in a collection or a document in a document.

It is important that you specify this.db.collection for a collection or subcollection, and this.db.doc for a collection's or subcollection's documents.

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