title: Mongodb aggregate $push with $cond and $each
body: <p>I'm trying to use <code>$cond</code> to conditionally <code>$push</code> multiple integers onto a numbers array during an aggregate <code>$group</code> without any success. Here is my code:</p>
  
  <pre><code>Item.aggregate(
      [
        {
          $group: {
            _id: "$_id",
            numbers: {
              $push: {
                $cond: { 
                  if: { $gt: [ "$price.percent", 70 ] }, 
                  then: { $each: [10,25,50,70] },
                  else: null,
                }
              }
            }
          }
        },
      ]
    )
    ...
  </code></pre>
  
  <p>Is Mongo DB just not set up for this right now, or am I looking at this all wrong?</p>