title: how to use "find" to search "_id => OBjectID("id")" in Perl API
body: <p>I have to find a kind of "_id" in my Mongo, I can do it using the Mongo shell, and I can not do that using Perl API.</p>
  
  <p>I'm trying to do it (mongo shell):</p>
  
  <pre><code>./mongo
  use my_db
  db.my_collection.find({_id : ObjectId("4d2a0fae9e0a3b4b32f70000")})
  </code></pre>
  
  <p>It works!(returns), but I can't do that using Perl API,</p>
  
  <pre><code>$mongo-&gt;my_db-&gt;my_collection(find({_id =&gt; "ObjectId(4d2a0fae9e0a3b4b32f70000"}));
  </code></pre>
  
  <p>Does not work because "ObjectId" is not a string, but if you do,</p>
  
  <pre><code>./mongo
  use my_db
  db.my_collection.find({_id : "ObjectId(4d2a0fae9e0a3b4b32f70000)"})
  </code></pre>
  
  <p>Does not work too, I'm guess Perl API are doing it ^</p>
  
  <p>Now, I have to know how I do it:</p>
  
  <pre><code>db.my_collection.find({_id : ObjectId("4d2a0fae9e0a3b4b32f70000")})
  </code></pre>
  
  <p>using Perl API.</p>