public IList <T> GetBy <T>(string appid, string id)
{
var mongodb = MongoDBHelper.GetMongoDB();
var collection = mongodb.GetCollection <T>(_colname);
FilterDefinition <T> wheres = Builders <T> .Filter.Eq("AppId", appid);
if (!string.IsNullOrWhiteSpace(id))
{
wheres = wheres & Builders <T> .Filter.Eq("Id", id);
}
return(collection.Find <T>(wheres).ToList <T>());
}