title: WP Shortcode to display posts by ID
body: <p>Currently, I have a shortcode that displays a specific set of posts by specifying the post ID inside the function. But I would like to change this so the user can specify the post IDs as shortcode attributes.</p>
  
  <p>Currently</p>
  
  <pre><code>[fsgrid]
  </code></pre>
  
  <p>Desired:</p>
  
  <pre><code>[fsgrid id="1, 2, 3"]
  </code></pre>
  
  <p>Here is the current code</p>
  
  <pre><code>public function shortcode_handler($atts) {
      $atts = shortcode_atts(
        array(
          'posts_per_page' =&gt; 100 ,
          'orderby' =&gt; 'post__in',
          'post__in' =&gt; array(1, 2, 3)
        ), $atts, 'fsgrid'
      );
  
      return $this-&gt;grid($atts);
    }
  </code></pre>
  
  <p>How do I change it? Any help is much appreciated.</p>