title: Twig add attribute with value in a variable
body: <p><strong>Using Drupal 8</strong></p>
  
  <p>I want to print out a field's content into the <code>src</code> attribute. I have the following template for my view:</p>
  
  <pre><code>&lt;div class="videoWrapperHD"&gt;
       &lt;iframe width="560" height="315" src="{{ rows[0].content | raw }}" 
        frameborder="0" allowfullscreen&gt;
       &lt;/iframe&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>But the iframe gets filled with my own site's "<em>Page Not Found</em>" page instead of the Youtube Video because Twig prints out a whole lot of debug comments before and after printing the variable <code>rows[0].content</code>. </p>
  
  <p>Is it possible to disable the debug comments for a specific field? I don't want to have to be disabling/enabling debug to make sure it works as expected.</p>
  
  <p>I also tried using <code>{{ attributes.setAttribute('src', {{ rows[0].content }} ) }}</code> , but no dice.</p>
  
  <p>Another failed attempt was:</p>
  
  <pre><code>{% set iframe_src = rows[0].content %}
  &lt;div class="videoWrapperHD"&gt;
      &lt;iframe width="560" height="315" {{ attributes.setAttribute('src', iframe_src) }}
       frameborder="0" allowfullscreen&gt;&lt;/iframe&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>My last idea was this:</p>
  
  <pre><code>{% set url = rows[0].content | raw %}
  {% set iframe_src = 'src=' ~ url %}
  
  &lt;div class="videoWrapperHD"&gt;
     &lt;iframe {{ iframe_src }} &gt;&lt;/iframe&gt;
  &lt;/div&gt; 
  </code></pre>
  
  <p>But it prints out <strong>src=Array</strong></p>