title: mongodb query $in operator, fetch by ObjectId in Array
body: <p>All my documents have a structure like this:</p>
  <pre><code>{
     operational: {availableFleet: [Objectid('5bad3f452641a1186d21b5f8'), ...]}
  }
  </code></pre>
  <p>So every document has an operational key with many other keys inside, one of them being availableFleet which is an Array of multiple ObjectIds</p>
  <p>I want to retrieve all documents that contain one specific ObjectId inside the availableFleet Array.</p>
  <p>Here's my query:</p>
  <pre><code>{operational: {availableFleet: {$in: [ObjectId('5bad3f452641a1186d21b5f8')]}}}
  </code></pre>
  <p>However, it's returning nothing.</p>
  <p>I'm using the MongoDB Compass GUI.</p>