title: How can I find records greater than or equal to a time in MongoDB?
body: <p>I have a MongoDB document structured like this:</p>
  
  <pre><code>{
  "_id": ObjectId("50cf904a07ef604c8cc3d091"),
  "lessons": {
      "0": {
          "lesson_name": "View and Edit Lists",
          "release_time": ISODate("2012-12-17T00:00:00Z"),
          "requires_anim": false,
          "requires_qq": true
      },
      "1": {
          "lesson_name": "Leave a Tip",
          "release_time": ISODate("2012-12-18T00:00:00Z"),
          "requires_anim": false,
          "requires_qq": true
      }
  }
  }
  </code></pre>
  
  <p>I have a number of such documents. I'd like to get all documents for which the release time of a lesson is greater than or equal to a given time. Here's the query I wrote:</p>
  
  <pre><code>db.lessons.find({"lessons.release_time":{"$gte": ISODate("2012-12-16")}});
  </code></pre>
  
  <p>But this is not returning any documents. Any ideas on what I'm doing wrong and how to correct it. Thanks.</p>