从Mixin访问iron元实例

<iron-meta></iron-meta> 实例?我可以在mixin中使用document.createElement,但只有一个 <铁元素></铁元素> 要处理的元素。

混音:

let rawApiConstantsMixin = (base) => {
  class foo extends base {
    constructor() {
      super();
    }

    ready() {
      super.ready(); 
      this.FORM_HOST = meta.byKey('FORM_HOST');
    }
  }
  return foo;
};

export const ApiConstantsMixin = dedupingMixin(rawApiConstantsMixin);

class MyView2 extends ApiConstantsMixin(PolymerElement) {
  static get template() {
    return html`
      <style include="shared-styles">
        :host {
          display: block;

          padding: 10px;
        }
      </style>

      <iron-meta></iron-meta>
      <div class="card">
        <div class="circle">2</div>
        <h1>View Two</h1>
        <p>Ea duis bonorum nec, falli paulo aliquid ei eum.</p>
        <p>Id nam odio natum malorum, tibique copiosae expetenda mel ea.Detracto suavitate repudiandae no eum. Id adhuc minim soluta nam.Id nam odio natum malorum, tibique copiosae expetenda mel ea.</p>
      </div>
    `;
  }
}

window.customElements.define('my-view2', MyView2);