title: Mongo database Query
body: <p>I'm new to mongo database.Please help me in writing the query updation. I already had a collection in mongo and i would like to add a new field in existing object field.the structure is as follows.</p>
  
  <pre><code>{
          "_class" : "PersistentContent",
          "originalId" : "2070",
          "videoInfo" : {
                  "test1" : ["res"]
          },
  }
  </code></pre>
  
  <p>I would like to update the structure to below format.</p>
  
  <pre><code>{
          "_class" : "PersistentContent",
          "originalId" : "2070",
          "videoInfo" : {
                  "test1" : ["res"],
                  "test2" : ["res2"]
          },
  }
  </code></pre>
  
  <p>How to update the collection and add  test2 into videoInfo tag. </p>