title: Find field type in mongodb using query
body: <p>I have collection containing some fields.</p>
  
  <p>Document structure is here:</p>
  
  <pre><code>    {
        date: ISODate("2014-03-19T23:00:00Z"),
        value: 25.8,
        name:"MyName"
      }
  </code></pre>
  
  <p>is there is way to find out data type of field?<br><br>
  how I can identify key <code>value</code> data type? either it is <code>double</code> or <code>float</code></p>