title: Mongodb find is not working with the Objectid
body: <p>Here is my code and I'm getting null value for the doc. But in the findOne({'webpageid':docs[i]._id} instead of docs[i]._id if I pass the webpageid it works. And I verified docs has the required webpage data</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>// get all the records from the webpages table
  var collection = db.get('webpages');
  collection.find({}, function(e,docs){
   // iterate over the webpage list
   for (var i = 0; i &lt; docs.length; i++) {
    // check if results table has any record for this webpage
    db.get('results').findOne({'webpageid':docs[i]._id}, function(err, doc)
    {
     if(err)
     {
      return;
     }
     console.log(doc);
    });
   };
  });</code></pre>
  </div>
  </div>
  </p>
  
  <p>Below is the content in the 'webpages' table</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>{
          "_id" : ObjectId("549608e16ecb16dc3c4880e6"),
          "name" : null,
          "url" : "http://www.google.com",
          "texttoverify" : null,
          "interval" : null,
          "websiteid" : null
  }
  {
          "_id" : ObjectId("549609986ecb16dc3c4880e7"),
          "name" : null,
          "url" : "http://www.google.com",
          "texttoverify" : null,
          "interval" : null,
          "websiteid" : null
  }
  {
          "_id" : ObjectId("54960a916ecb16dc3c4880e8"),
          "name" : "xyz",
          "url" : "http://www.google.com",
          "texttoverify" : "hello",
          "interval" : "00:15:00.0000000",
          "websiteid" : "02D7BE81-4E01-4347-BAE5-BA9A2D7EE11E"
  }</code></pre>
  </div>
  </div>
  </p>
  
  <p>Here is my content inside 'results' table</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>{
          "_id" : ObjectId("54985a1e69af082f9c477574"),
          "webpageid" : "549608e16ecb16dc3c4880e6"
  }
  { "_id" : ObjectId("54986f4e69af082f9c477575"), "name" : "name" }
  {
          "_id" : ObjectId("5498d10c69af082f9c477576"),
          "name" : "name",
          "webpageid" : "\"54960a916ecb16dc3c4880e8"
  }
  {
          "_id" : ObjectId("5498d1f969af082f9c477577"),
          "name" : "name",
          "webpageid" : "54960a916ecb16dc3c4880e8"
  }</code></pre>
  </div>
  </div>
  </p>
  
  <p>Thanks for looking into it and appreciate your help.</p>