Creating a simple unit of work with Entity Framework and no repository

I've been trying to implement a .NET MVC Unit of Work API (rather than creating a separate repository), but it doesn't feel right. Am I going about this the correct way?

Following advice from here.

BaseController

public class BaseController : ApiController
    {
        protected DBEntities _dbEntities;

        protected override void OnActionExecuting(ActionExecutingContext filterContext)
        {
            _dbEntities = new DBEntities();
        }

        protected override void OnActionExecuted(ActionExecutedContext filterContext)
        {
            _dbEntities.SaveChanges();
        }
    }

MyController

public class MyController : BaseController
{
    public HttpResponseMessage PutMyObject(int id, int id2)
    {
        if (id != 0)
        {
            var myObject = _dbEntities.MyObjects.Where(x => x.id == id);
            if (myObject.Count() > 0)
            {
                MyObject temp = myObject.SingleOrDefault();
                temp.Processed = true;
                return Request.CreateResponse(HttpStatusCode.OK);
            }
            else
            {
                return Request.CreateErrorResponse(HttpStatusCode.NotFound);
            }
        }
        else
        {
            /* do some other stuff */
        }
    }             

}

My thinking around this is that the controller action is a single Unit of Work. The database connection is opened when the controller action starts, and SaveChanges is called once the response is returned.

Am I going about this in the correct manner? Do I need to dispose of _dbentities after SaveChanges is called within the BaseController?