title: How to override the document in MongoDB
body: <p>I have mongodb collection with below document</p>
  
  <pre><code>{
      "_id" : ObjectId("5652f7e1a9fddf438369c866"),
      "USER_ID" : "Vinsy",
      "USER_NAME" : "Vinsy",
      "FIRST_NAME" : "XYZxx",
      "LAST_NAME" : "ABC",
      "CONTACTS"  :[]
  }
  </code></pre>
  
  <p>I am trying to update the document with below query</p>
  
  <pre><code>collection.update({
          USER_ID: req.body.USER_ID
      },{
          "USER_ID" : "Vinsy",
          "USER_NAME" : "Vinsy",
          "FIRST_NAME" : "XYZxx",
          "LAST_NAME" : "ABC",
      }, function(error, data) {
  
          try {
              if (data) {
                  res.json("SUCCESS");
              } else {
                  res.json("FAILURE" + error);
              }
          } catch (e) {
              res.json("FAILURE" + e);
          }
      });
  </code></pre>
  
  <p>The query is updating the document but it's removing CONTACTS. How to keep it as it is? really appreciate you help.</p>