title: Angular 4 - Dynamically added meta tags not working
body: <p>I am using Meta service of Angular 4 - </p>
  
  <pre><code>import { Meta } from '@angular/platform-browser';
  
   constructor(private _router: Router,
      private _meta: Meta) {
   }
  
  afterRequestSuccess(){
      this._meta.addTag({ property: 'og:description', content: "desc comes from api response" });
      this._meta.addTag({ property: 'og:image', content: "Image path comes from api resonse" });
  }`
  </code></pre>
  
  <p>I can see on added tags in google chorme developer tool but I am trying on facebook Graph Object Debugger
  <a href="https://developers.facebook.com/tools/debug/og/object" rel="nofollow noreferrer">https://developers.facebook.com/tools/debug/og/object</a> that time is does not show in the debugger response list.</p>
  
  <p>Can some one help ? thanks in advance.</p>