title: How to get child document from a collection in mondodb?
body: <p>I have created a collection which has sub collection data. I want to filter from sub collection with a key. </p>
  
  <p>Here is my document:</p>
  
  <pre><code>{
      "_id" : ObjectId("5758098356e3930537af15dd"),
      "manpower_data" : [ 
          {
              "_id" : ObjectId("5758098356e3930537af15de"),
              "created" : ISODate("2016-06-08T12:03:15.387Z"),            
              "designation" : "Visiting Evaluator",            
              "evaluatorContactNumber" : "987654321",            
              "evaluatorName" : "Dumy User1",
              "dealerCodeFor" : "ZSAE876",
              "region" : "Gurgaon"
          }, 
          {
              "_id" : ObjectId("5758098356e3930537af15de"),
              "created" : ISODate("2016-06-08T12:03:15.387Z"),            
              "designation" : "Resident Evaluator",            
              "evaluatorContactNumber" : "987654321",            
              "evaluatorName" : "Dumy User2",
              "dealerCodeFor" : "ZSAE877",
              "region" : "Delhi"
          }
      ]
  }
  </code></pre>
  
  <p>When I run this query </p>
  
  <p><code>db.mycollection.find({"manpower_data.dealerCodeFor":"ZSAE876"});</code> </p>
  
  <p>It returns me all two sub document but I want to get only those <code>manpower data</code> which has matching <code>dealerCodeFor</code>.</p>