从单个文档 Angular 和 Firestore 检索值

Question

我正在尝试使用 Angular 从 Firestore 文档中获取各个值。

我的 TypeScript 代码：

userDoc: AngularFirestoreDocument<User>;
user: Observable<User>;

ngOnInit() {
    this.userDoc = this.afs.doc('users/' + this.af.auth.currentUser.uid);
    this.user = this.userDoc.valueChanges();
}

然后是 HTML：

{{ user | async | json }}

返回此：

{ "email": "[email protected]", "firstname": "x", "lastname": "x", "phone": "x", "subscription": x, "uid": "x" }

这正是我需要的......

但是当我尝试获得像这样的个人价值时：

<p>
   Your email is: {{ user.email | async }}
</p>

我无法获取单个值。如何“解开”可观察值以获得单个值？

Answer 1

我找到了答案，很简单：

{{(user | async)?.email }}

解开数据。如果有人能更好地解释这一点那就太好了！

Answer 2

this.firestoreData = this.firestore.getCollection(this.dataPath); //where dataPath = the collection name

this.firestoreData.subscribe(firestoreData => {
                
   for (let dID of firestoreData ) {
      if (dID.field1 == this.ClassVariable1) {
          if (dID.field2 == '') {
                this.ClassVariable2 = dID.id; //assign the Firestore documentID to a class variable for use later
          }
      }
   }
} );