public void CreateTopic(Topic topic, string username)
{
string newid = Guid.NewGuid().ToString();
var now = DateTime.UtcNow;
topic.id = newid;
topic.CreateDate = now;
topic.CreateBy = username;
topic.VoteList = new List <Vote>();
if (topic.ChoiceList.Count() == 0)
{
topic.ChoiceList = new List <Choice>();
}
dac.CreateTopic(topic);
}