title: How to push items into an array in mongoose
body: <p>I have a problem where I am creating  a user and want to save some items associated to this user at the same time.  </p>
  
  <p>I have managed to get it where I can create an item and reference the user_id associated to that item but I cant work out how to push all the items the user has into the User schema.  </p>
  
  <p>I have tried looping through req.body.taken and adding to user schema but I just get null returned.</p>
  
  <pre><code>router.post('/data', async (req, res) =&gt; {
  
  
    var user = new User({
      name: req.body.name,
      website: req.body.website,
    })
  
    user.save(function (err) {
      if (err) {
        return next(err);
      }
    })
  
    req.body.taken.forEach((item) =&gt; {
  
      var item = new Item({
        x: item.x,
        y: item.y,
        xSize: item.xSize,
        ySize: item.xSize,
        user: user,
        imageSource: item.imageSource,
        user: user
      }
      )
  
      item.save(function (err) {
        if (err) {
          return next(err);
        }
      })
  
  
  
    })
  
  const UserSchema = new Schema(
    {
      id: Number,
      name: String,
      website: String,
      items: [{
          type: mongoose.Schema.Types.ObjectId,
          ref: 'Item'
        }]
  
    },
    { timestamps: true }
  );
  
  const ItemSchema = new Schema(
    {
      id: Number,
      x: Number,
      y: Number,
      xSize: String,
      ySize: String,
      imageSource: String,
      user: { type: mongoose.Schema.ObjectId, ref: 'User' }
    },
    { timestamps: true }
  );
  
  
    User.find({})
        .populate('items')
        .exec(function(error, items) {
            console.log(items)
        })
  
  
  </code></pre>
  
  <p>When I call User find I want to get all items associated to that user (which will be an array as req.body.taken is an array of items.</p>