title: Mongoose query returning empty array
body: <p>Below is my express endpoint that returns an empty array</p>
  
  <pre><code>router.get('/myUnits/:landlord_id', wagner.invoke((Apartment) =&gt; {
      return (req, res) =&gt; {
        Apartment.find({ postedBy: req.params.landlord_id }, (err, apt) =&gt; {
          if (err) {
            return res.status(status.INTERNAL_SERVER_ERROR)
                      .json({ error: err.toString() })
          }
          if (!apt) {
            return res.status(status.NOT_FOUND)
                      .json({ error: 'Not found' })
          }
          return res.json(apt)
        })
      }
    }))
  </code></pre>
  
  <p>I changed <code>Apartment.find({ price: 200 })</code> and it queries all data with the <code>price: 200</code> but querying for <code>postedBy</code> does not work at all.</p>
  
  <p>When I go to my mongo shell and do a query</p>
  
  <pre><code>db.apartments.find({ postedBy: 'the id of the account here' })
  </code></pre>
  
  <p>it returns the appropriate data.</p>
  
  <p><a href="https://gyazo.com/77afa64f9afb75f47667d0f47757c3e4" rel="nofollow"><img src="https://i.gyazo.com/77afa64f9afb75f47667d0f47757c3e4.png" alt="https://gyazo.com/77afa64f9afb75f47667d0f47757c3e4"/></a></p>