title: Specify timezone of datetime without changing value
body: <p>I'm wondering how to go about changing the timezone of a DateTime object without actually changing the value. Here is the background...</p>
  
  <p>I have an ASP.NET MVC site hosted on AppHarbor and the server has its time set to UTC. When I submit a form from my site containing a datetime value, say 9/17/2013 4:00am, it comes up to the server with that value. However then when I do:</p>
  
  <pre><code>public ActionResult Save(Entity entity)
  {
      entity.Date = entity.Date.ToUniversalTime();
      EntityService.Save(entity);
  }
  </code></pre>
  
  <p>...it incorrectly keeps it as the same time (4am) because the server is already on UTC time. So after converting to UTC and saving to the database, the database value is 2013-09-17 04:00:00.000, when really it should be 2013-09-17 08:00:00.000, as the browser is on EST. I was hoping after form submission and passing the values to the controller action, it would set the DateTime's timezone to the browser's (EST) rather than the server host's (UTC), however that didn't happen.</p>
  
  <p>In any case, now I'm stuck with a DateTime object that contains the correct date/time value but the wrong time zone, so I can't correctly convert it to UTC. I store the time zone of each user, so if there was a way to set the time zone for the DateTime object without actually changing the value (I can't do TimeZoneInfo.ConvertTime because it'll change the value) then I could have the correct date/time value AND the correct time zone, then I could safely do date.ToUniversalTime. That being said, I've only seen how to change the KIND of a DateTime, not the TimeZone, without changing its actual value.</p>
  
  <p>Any ideas?</p>