Firebase/Angularfire：访问观测值的静态值

假设我有一个Firebase对象，其中包含一些ID的名称：

people: {
  key1: {name: "Bob"},
  key2: {name: "Sally"},
  ...
}

我创建了一个可观察的角度列表：

this.people$ = this.angularFireDatabase.list('people');

并将其作为

<span *ngFor="let person of people$ | async">Hello {{person.key}}</span>

然后

但是，这需要我在

ngondestory

中跟踪订阅和取消订阅

Two：在可观察到的物体上使用

take

：

public create() {
  this.people$.take(1).subscribe(people =>
    this.people.push({name: "person " + (people.length + 1)});
  );
}

但这能可靠地获得可观测数据的当前值吗

Three：回到Angular数据库本身，进入引用和快照的世界，然后

public create() {
  this.people$.$ref.once("value").then(peopleSnapshot =>
    this.people.push({name: "person " + (peopleSnapshot.numChildren() + 1)});
}

---

这三种方法中有哪一种被认为是最佳实践，或者它们还有哪些优缺点？

对于静态变量，您可以使用src/environments/environment.ts文件夹保存json格式的静态信息，并使用

environment.myvar

在你的app.modules.ts中

imports: [ AngularFireModule.initializeApp(environment.firebase),

import { environment } from '../environments/environment';

public create() {
  this.people$.$ref.once("value").then(peopleSnapshot =>
    this.people.push({name: "person " + (peopleSnapshot.numChildren() + 1)});
}

imports: [ AngularFireModule.initializeApp(environment.firebase),

import { environment } from '../environments/environment';