title: How to create a collection from JSON data in MongoDB?
body: <p>I have the following J SON data. How to sum balance of the following collection?</p>
  
  <pre><code>"_id" : ObjectId("592595a1bca1350220027666"),
  "user_account" : "5-5XX4XX-X06",
  "Xns" : {
          "Xn" : [
                  {
                          "date" : "2015-09-01",
                          "narration" : "ATM/CASH WDL/01-01-10/17:48:45/0",
                          "amount" : "-2500.00",
                          "category" : "Others",
                          "balance" : "110578.04",
                          "_id" : ObjectId("592595a1bca13502200276ca")
                  },
                  {
                          "date" : "2015-09-04",
                          "narration" : "EBA//20100104081107",
                          "amount" : "-7206.12",
                          "category" : "Others",
                          "balance" : "103371.92",
                          "_id" : Object Id("592595a1bca13502200276c9")
                  }
  </code></pre>