title: How to find comments by user_id in group_id in mongoose
body: <p>I have two models (account.js and group.js)
  <a href="https://i.stack.imgur.com/aBVJL.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/aBVJL.png" alt="enter image description here"></a></p>
  
  <p><a href="https://i.stack.imgur.com/8osWc.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/8osWc.png" alt="enter image description here"></a>
  <a href="https://i.stack.imgur.com/mK3x1.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/mK3x1.png" alt="enter image description here"></a>
  I can find all comments in a group by query:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>  Group.findOne({_id:req.body.groupid}).
    populate({
      path: 'comment.user',
    }).
    exec((err,data)=&gt;{
      // console.log(data);
      res.json({
        mss: data,
      });
    });</code></pre>
  </div>
  </div>
  </p>
  
  <p>Now I want to find all comments of a user with specific id (user._id) in a specific group (group._id). Any one can help. Thank for advance.</p>