@默认情况下，tracked不会观察到对象的深层变化，因此需要使用扩展运算符obj = {...obj}告诉tracked obj已更改，或者可以使用ember-deep-tracked，并通过观察user.account来调用getChildItems。status您可以使用ember-render-modifiers提供的渲染挂钩，如模板级别的did-insert，例如以下代码：，

// services/user.js
import Service from '@ember/service';
import {tracked} from '@glimmer/tracking';
import {action} from '@ember/object';

export default class UserService extends Service {
  @tracked account;
  @tracked items=[];

  constructor(...args) {
    super(...args);

    this.account = {
      name: 'myname1',
      status: 'active',
    };
  }

  @action
  changeStatus(status) {
    this.account.status = status;
    this.account = {...this.account}
  }

 @action
  getChildItems() {
      const itemsFromApi = [1,2,3,4,5]
     this.items = [...itemsFromApi];
  }
}

// components/navbar.js
import Component from '@glimmer/component';
import {inject as service } from '@ember/service';
export default class NavbarComponent extends Component {

  @service user;
}

{{!-- components/navbar.hbs --}}
Status:{{this.user.account.status}}

<button type="button" {{on 'click' (fn this.user.changeStatus
  (if (eq this.user.account.status 'active') 'notActive' 'active'))}}>
  Change status
</button>

{{#if (eq this.user.account.status 'active')}}

  <ul {{did-insert this.user.getChildItems}}>
    {{#each this.user.items as |item|}}
      <li>{{item}}</li>
    {{/each}}
  </ul>
{{/if}}

{{!-- templates/application.hbs --}}
{{page-title "Testproject"}}

<Navbar/>

{{outlet}}