title: Mongoose findByID from URL route parameter not working with Express router
body: <p>I saw this in a tutorial but can't make it work:</p>
  
  <pre><code>/* GET one item. */
  router.get('/items/:id', (req, res) =&gt; {
    Item.findById(req.param.id, (err, items) =&gt; {
      if (err) res.status(500).send(error)
  
      res.status(200).json(items);
    });
  });
  </code></pre>
  
  <p>I also tried "<code>.findById({_id: req.params.id}</code>"</p>
  
  <p>I always get the whole list of items.
  I can not find the proper way to implement <code>findById</code> from the documentation with <code>router.get</code></p>