title: Firebase realtime database filter by date child node and update
body: <p>I have a real-time database and one of its collections looks something like this:</p>
  
  <pre><code>"VisitorRecords" : {
      "1558098355174" : {
        "CardReturnApprovedBy" : "IXWjlt15qJPkjNDbl4PqG1cT13",
        "CreatedBy" : "IXWjlt15qJPkjNDblqG1cc0T13",
        "DatetimeCreated" : "Fri, 17 May 2019 13:05:55 GMT",
        "Status": 1
      },
      "1558445445664" : {
        "CardReturnApprovedBy" : "",
        "CreatedBy" : "IXWjlt15qJPkjNl4PqG1cc0T13",
        "DatetimeCreated" : "Tue, 21 May 2019 13:30:45 GMT",
        "Status": 1
      }
    }
  </code></pre>
  
  <p>My idea here is to filter all of the visitor records which have their <strong>DatetimeCreated</strong> bigger or equal to DateTime.Now (UTC) and then I want to update the <strong>Status</strong> property to <strong>2</strong>. I want to do that from a firebase function.</p>
  
  <p>What I've found so far is <strong>startAt(), endAt()</strong> helper functions but they don't seem to work in my case. Other option is to iterate all of the records and do a manual check for the date. Then, try to update this specific record using <strong>.update</strong></p>
  
  <p>I was wondering if there's no more simple and elegant way of doing this.</p>