假设您的操作，changeProject看起来像这样：

@action
changeProject(projectName, data) {
  this.data = data.filter(project => project.name.includes(projectName));
}

this.data不工作的观察是正确的，也是有意的，因为@data在this.args.data上可用，但this.args的每个键都是不可变的。
因此，在组件中，为了引用过滤后的数据，可能需要创建一个别名：

get filteredData() {
  return this.args.data;
}

在模板中：

{{#each this.filteredData as |project|}}
  ...

然后您的操作也需要更新，因为我们仍然无法设置filteredData*或this.args.data

import Component from '@glimmer/component';
import { tracked } from '@glimmer/tracking';
import { action } from '@ember/object';

export default class Demo extends Component {
  @tracked filtered;

  get filteredData() {
    return this.filtered ?? this.args.data;
  }

  @action
  changeProject(projectName) {
    this.filtered = this.args.data.filter(project => project.name.includes(projectName));
  }
}

{{#each this.filteredData as |project|}}
  <ItemList @categories={{project.category}}/>
{{/each}}

...
<ul>
  {{#each @data as |project}}
    <li 
      class="inline hover:underline cursor-pointer ml-4" 
      {{on "click" (fn this.changeProject project.name)}}
    >
      {{project.name}}
    </li>
  {{/each}}
</ul>