title: How to make this kind of aggregation in Mongo?
body: <p>I have MongoDB 4.x with collection, which have documents like this</p>
  
  <p><a href="https://i.stack.imgur.com/vbzJx.jpg" rel="nofollow noreferrer">image</a></p>
  
  <p>how to make agregation, that return only bot-field, where _id is X?
  I've tried to use $project:</p>
  
  <p><code>
  {
      _id: 0,
      bot: {$filter: {
          input: '$clusters.bots',
          as: 'bot',
          cond: {$eq: ['$$bot._id', 'X']}
        }}
      }</code></p>