title: MongoDB advanced $lookup Query
body: <p>I want to join two collections and get data.I know that this can be achieved by using $lookup, but the case is 'from' field in $lookup should have a dynamic value as explained below.</p>
  
  <p>There are three collections in my db : inclusions,packages,page_content</p>
  
  <p><a href="https://i.stack.imgur.com/bY54N.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/bY54N.png" alt="enter image description here"></a>   </p>
  
  <p>I think you got what I meant..If there is any one who can help with this appreciate if..</p>