public void DeleteContentType(ContentType contentType)
        {
            //Argument Contract
            Requires.NotNull("contentType", contentType);
            Requires.PropertyNotNegative("contentType", "ContentTypeId", contentType.ContentTypeId);

            _DataService.DeleteContentType(contentType);

            //Refresh cached collection of types
            DataCache.RemoveCache(_CacheKey);
        }
        public int AddContentType(ContentType contentType)
        {
            //Argument Contract
            Requires.NotNull("contentType", contentType);
            Requires.PropertyNotNullOrEmpty("contentType", "ContentType", contentType.Type);

            contentType.ContentTypeId = _DataService.AddContentType(contentType);

            //Refresh cached collection of types
            DataCache.RemoveCache(_CacheKey);

            return contentType.ContentTypeId;
        }
        private void LoadContentTypeList2DDL()
        {
            ContentType content_types_obj = new ContentType();
            DataTable dt_content_types = content_types_obj.GetAll(); //select all the nodes from DB

            ddlContentTypes.Items.Clear();
            ddlContentTypes.DataSource = dt_content_types;
            ddlContentTypes.DataTextField = "ContentType";
            ddlContentTypes.DataValueField = "ContentTypeID";
            ddlContentTypes.DataBind();
            //ddlContentTypes.Items.Insert(0, new ListItem("- Chọn -", ""));
            ddlContentTypes.SelectedIndex = 0;
            ddlContentTypes.AutoPostBack = true;

        }