愛上MVC~為CheckBoxFor和RadioButtonFor加個擴展方法吧（希望MVC5把這方法收納——呵呵）

文章出處

說在前

我都是喜歡把問題復雜化，還有總是喜歡把問題簡單化，偷懶化，這也需就是一個程序員的追求吧，呵呵。

我不太喜歡重復的東西，當你看到頁面上有一個以上相同的代碼時，那可以說，你的代碼有重構的余地，應該考慮重構了，今天看了以前同事的博客，寫了關于DropDownList的用法，如何將集合數據綁定到下拉列表框上，講的不錯，但最后在說checkbox和radiobutton時，我感覺有點重復了，我說的是代碼重復了，還有就是代碼復雜化了，就是說，我再使用集合來產生checkbox和radiobutton時，代碼有些復雜了，這不是我們希望看到的，所以，我覺得有必要把它重構一下，為mvc加兩個擴展方法吧，呵呵。

做在后

DropDownListFor的方法簽名做的不錯，很面向對象，很簡潔，但不知不何，checkbox和radiobutton確沒有這樣的重載，呵呵

        public static MvcHtmlString DropDownListFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList);
        public static MvcHtmlString DropDownListFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, IDictionary<string, object> htmlAttributes);
        public static MvcHtmlString DropDownListFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, object htmlAttributes);
        public static MvcHtmlString DropDownListFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, string optionLabel);
        public static MvcHtmlString DropDownListFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, string optionLabel, IDictionary<string, object> htmlAttributes);
        public static MvcHtmlString DropDownListFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, string optionLabel, object htmlAttributes);

對于checkbox和radiobutton它們只有簡單的幾個重載，沒有對集合的支持，所以，我的這次代碼擴展，主要是針對集合來說的，看方法簽名：

下面看一下原代碼，它直接寫在了System.Web.Mvc命名空間下，這更說明我是對微軟MVC的一個擴展，希望MVC5出來時，可以把這些都集成進去，呵呵

#region 單選框和復選框的擴展
        /// <summary>
        /// 復選框,selValue為選中項
        /// </summary>
        /// <param name="htmlHelper"></param>
        /// <param name="name"></param>
        /// <param name="selectList"></param>
        /// <param name="selValue"></param>
        /// <returns></returns>
        public static MvcHtmlString CheckBox(this HtmlHelper htmlHelper, string name, IEnumerable<SelectListItem> selectList, IEnumerable<string> selValue)
        {
            return CheckBoxAndRadioFor<object, string>(name, selectList, false, selValue);
        }
        public static MvcHtmlString CheckBox(this HtmlHelper htmlHelper, string name, IEnumerable<SelectListItem> selectList, string selValue)
        {
            return CheckBox(htmlHelper, name, selectList, new List<string> { selValue });

        }
        /// <summary>
        /// 復選框
        /// </summary>
        /// <param name="htmlHelper"></param>
        /// <param name="name"></param>
        /// <param name="selectList"></param>
        /// <returns></returns>
        public static MvcHtmlString CheckBoxFor(this HtmlHelper htmlHelper, string name, IEnumerable<SelectListItem> selectList)
        {
            return CheckBox(htmlHelper, name, selectList, new List<string>());
        }
        /// <summary>
        /// 根據列表輸出checkbox
        /// </summary>
        /// <typeparam name="TModel"></typeparam>
        /// <typeparam name="TProperty"></typeparam>
        /// <param name="htmlHelper"></param>
        /// <param name="expression"></param>
        /// <param name="selectList"></param>
        /// <returns></returns>
        public static MvcHtmlString CheckBoxFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList)
        {
            return CheckBoxFor(htmlHelper, expression, selectList, null);
        }

        /// <summary>
        ///  根據列表輸出checkbox,selValue為默認選中的項
        /// </summary>
        /// <typeparam name="TModel"></typeparam>
        /// <typeparam name="TProperty"></typeparam>
        /// <param name="htmlHelper"></param>
        /// <param name="expression"></param>
        /// <param name="selectList"></param>
        /// <param name="selValue"></param>
        /// <returns></returns>
        public static MvcHtmlString CheckBoxFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, string selValue)
        {
            string name = ExpressionHelper.GetExpressionText(expression);
            return CheckBoxAndRadioFor<TModel, TProperty>(name, selectList, false, new List<string> { selValue });
        }
        /// <summary>
        /// 輸出單選框和復選框
        /// </summary>
        /// <typeparam name="TModel"></typeparam>
        /// <typeparam name="TProperty"></typeparam>
        /// <param name="expression"></param>
        /// <param name="selectList"></param>
        /// <param name="isRadio"></param>
        /// <param name="selValue"></param>
        /// <returns></returns>
        static MvcHtmlString CheckBoxAndRadioFor<TModel, TProperty>(
            string name,
            IEnumerable<SelectListItem> selectList,
            bool isRadio,
            IEnumerable<string> selValue)
        {
            StringBuilder str = new StringBuilder();
            int c = 0;
            string check, activeClass;
            string type = isRadio ? "Radio" : "checkbox";

            foreach (var item in selectList)
            {
                c++;
                if (selValue != null && selValue.Contains(item.Value))
                {
                    check = "checked='checked'";
                    activeClass = "style=color:red";
                }
                else
                {
                    check = string.Empty;
                    activeClass = string.Empty;
                }
                str.AppendFormat("<span><input type='{3}' value='{0}' name={1} id={1}{2} " + check + "/>", item.Value, name, c, type);
                str.AppendFormat("<label for='{0}{1}' {3}>{2}</lable></span>", name, c, item.Text, activeClass);

            }
            return MvcHtmlString.Create(str.ToString());
        }


        public static MvcHtmlString RadioButton(this HtmlHelper htmlHelper, string name, IEnumerable<SelectListItem> selectList, IEnumerable<string> selValue)
        {
            return CheckBoxAndRadioFor<object, string>(name, selectList, true, selValue);
        }
        /// <summary>
        /// 單選按鈕組，seletList為選中項
        /// </summary>
        /// <param name="htmlHelper"></param>
        /// <param name="name"></param>
        /// <param name="selectList"></param>
        /// <param name="selValue"></param>
        /// <returns></returns>
        public static MvcHtmlString RadioButton(this HtmlHelper htmlHelper, string name, IEnumerable<SelectListItem> selectList, string selValue)
        {
            return RadioButton(htmlHelper, name, selectList, new List<string> { selValue });
        }
        /// <summary>
        /// 單選按鈕組
        /// </summary>
        /// <param name="htmlHelper"></param>
        /// <param name="name"></param>
        /// <param name="selectList"></param>
        /// <returns></returns>
        public static MvcHtmlString RadioButton(this HtmlHelper htmlHelper, string name, IEnumerable<SelectListItem> selectList)
        {
            return RadioButton(htmlHelper, name, selectList, new List<string>());
        }
        /// <summary>
        ///  根據列表輸出radiobutton
        /// </summary>
        /// <typeparam name="TModel"></typeparam>
        /// <typeparam name="TProperty"></typeparam>
        /// <param name="htmlHelper"></param>
        /// <param name="expression"></param>
        /// <param name="selectList"></param>
        /// <returns></returns>
        public static MvcHtmlString RadioButtonFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList)
        {
            return RadioButtonFor(htmlHelper, expression, selectList, new List<string>());
        }
        public static MvcHtmlString RadioButtonFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, IEnumerable<string> selValue)
        {
            string name = ExpressionHelper.GetExpressionText(expression);
            return CheckBoxAndRadioFor<TModel, TProperty>(name, selectList, true, selValue);
        }
        /// <summary>
        /// 根據列表輸出radiobutton,selValue為默認選中的項
        /// </summary>
        /// <typeparam name="TModel"></typeparam>
        /// <typeparam name="TProperty"></typeparam>
        /// <param name="htmlHelper"></param>
        /// <param name="expression"></param>
        /// <param name="selectList"></param>
        /// <param name="selValue"></param>
        /// <returns></returns>
        public static MvcHtmlString RadioButtonFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, string selValue)
        {
            return RadioButtonFor(htmlHelper, expression, selectList, new List<string> { selValue });
        }
        #endregion