title: MongoDb return a UTC DateTime when I stored a Local DateTime by C# driver
body: <p>MongoDb: 3.2 x64
  C# driver: Official C# driver 2.2</p>
  
  <p>After I have written a instance of TestClass, and retrieve it afterwards. I find the field "DataTime" has been changed into UTC DateTime.</p>
  
  <p>Of course I know c# driver write DateTime with UTC format, but it is so wired to convert it to UTC automatically and do nothing when I retrieve it from mongo.</p>
  
  <p>I used "samus" driver before which convert DateTime to UTC format while writing to mongo and converting to Local DateTime while you retrieve it.</p>
  
  <p>Here is the test codes:</p>
  
  <pre><code>using System;
  using Microsoft.VisualStudio.TestTools.UnitTesting;
  
  using MongoDB;
  using MongoDB.Bson;
  using MongoDB.Bson.Serialization.Attributes;
  using MongoDB.Driver;
  
  namespace Test
  {
      [TestClass]
      public class UnitTest1
      {
          [TestMethod]
          public void TestMethod1()
          {
              var client = new MongoClient("mongodb://root:root@127.0.0.1");
              var db = client.GetDatabase("Test");
              var col = db.GetCollection&lt;TestClass&gt;("TestClass");
  
              var data = new TestClass(DateTime.Now.ToString());
              col.InsertOne(data);
  
              var find = Builders&lt;TestClass&gt;.Filter.Eq("_id", data.DataTime);
              var fo = new FindOptions&lt;TestClass&gt;();
              fo.Limit = 1;
              var t = col.FindSync(find, fo);
              var data_ret = t.ToList()[0];
  
              Assert.AreEqual(data.Text, data_ret.Text);
              Assert.AreEqual(data.DataTime, data_ret.DataTime);            
          }
      }
  
      public class TestClass
      {
          public TestClass()
          {
          }
  
          public TestClass(string arg_strText)
          {
              DataTime = DateTime.Parse(DateTime.Now.ToString());
              Text = arg_strText;
          }   
  
          [BsonId]
          public DateTime DataTime;
          public string Text;
      }
  }
  </code></pre>