title: MongoDB populate returning null
body: <p>I am trying to populate my user schema with items but for some reason it does not populate anything in to the user schema. Could someone please take a look. I have 1 user and 1 item belonging to that user within my database but nothing is populating and I keep seeing null.</p>
  <p>User Schema</p>
  <pre><code>var mongoose = require('mongoose')
  
  var userSchema = mongoose.Schema({
      name: {
          type: String,
          required: true
      },
      discordID: {
          type: String,
          required: true
      },
      discordImage: {
          type: String,
          required: true
      },
      items: [{
          type: mongoose.Schema.Types.ObjectId,
          ref: 'Item'
      }]
  })
  
  const User = module.exports = mongoose.model('User', userSchema)
  </code></pre>
  <p>Item Schema</p>
  <pre><code>var mongoose = require(&quot;mongoose&quot;)
  
  var itemSchema = mongoose.Schema({
      name: {
          type: String,
          required: true
      },
      purchasedPrice: {
          type: Number,
          required: true
      },
      purchasedDate: {
          type: String,
          required: true
      },
      author: {
          type: mongoose.Schema.Types.ObjectId,
          required: true,
          ref: &quot;User&quot;
      }
  })
  
  const Item = module.exports = mongoose.model(&quot;Item&quot;, itemSchema)
  </code></pre>
  <p>Populate Code</p>
  <pre><code>app.get(&quot;/inventory&quot;, async (req, res) =&gt; {
      try {
          await req.user.populate({
              path: 'items'
          }).execPopulate()
          console.log(req.user)
      } catch (error) {
          console.log(error)
      }
      res.status(200).render(&quot;inventory.ejs&quot;, { currentUser: req.user })
  })
  </code></pre>
  <p>Objects in the DB:</p>
  <p>Item:</p>
  <p><a href="https://i.stack.imgur.com/EUEdM.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/EUEdM.png" alt="enter image description here" /></a></p>
  <p>User:</p>
  <p><a href="https://i.stack.imgur.com/lWVXZ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/lWVXZ.png" alt="enter image description here" /></a></p>