title: What is the correct way to query MongoDB for _id using string by using Python?
body: <p>I am using pymongo driver.  Supposedly, one can use a string to query the _id field of a document, like this:</p>
  
  <pre><code>thing = db.things.find_one({'_id':'4ea113d6b684853c8e000001'})
  </code></pre>
  
  <p>But it doesn't work.  What am I doing wrong?</p>