title: Need to push data in nested subdocument array
body: <p>I need to push data in nested subdocument array(replyComment):</p>
  <p>This is an example of a document from my database:</p>
  <pre><code>{
    comments: [
      {
        replyComment: [],
        _id: 601a673735644c83e0aa1be3,
        username: 'xyz123@gmail.com',
        email: 'xyz213@gmail.com',
        comment: 'test123'
      },
      {
        replyComment: [],
        _id: 601a6c94d1653c618c75ceae,
        username: 'xyz123@gmail.com',
        email: 'xyz123@gmail.com',
        comment: 'reply test'
      }
    ],
    _id: 601a3b8038b13e70405cf9ea,
    title: 'latest test',
    snippet: 'latest test snippet',
    body: 'latest test body',
    createdAt: 2021-02-03T05:58:24.123Z,
    updatedAt: 2021-02-03T12:28:33.237Z,
    __v: 7
  }
  </code></pre>
  <p>I am also mentioning my code snippet:</p>
  <pre><code>app.post('/:id/replyComment',(req,res) =&gt; { 
    const replyComm = new Comment(req.body);
    Topic.findById(req.params.id)
    .then((result) =&gt; {
      topic = result,
      console.log(topic);
      topic.update({_id:req.params.id, &quot;comments._id&quot;: req.body.comment_id},
        { $push: {&quot;comments.$.replyComment&quot;: {replyComment: replyComm}}}
      )
      topic.save()
      .then((result) =&gt; {
        // console.log(result);
          res.send({
            text: &quot;Replied&quot;,
          })
      })
      .catch((err) =&gt; {
          console.log(err);
      });
    })
  });
  </code></pre>
  <p>By running the request I am not getting any error but still the same documented is getting printed on my terminal and there is no change in &quot;replyComment&quot; subarray.
  Pls suggest how to make this work or any alternate method.</p>