扩展RadioButtonListFor和CheckBoxListFor

         在我们做正常的MVC的开发中，一些基本的控件已经够用了，但是有时候我们需要用到库里面没有的一些控件，比如RadioButtonListFor和CheckBoxListFor这类的列表控件，在MVC库里面没提供，需要自己来扩展一下。我们通过MvcHtmlString扩展的控件，最终还是被转换为html标签的形式，所以扩展控件实质上还是拼标签。其中用到TagBuilder这个类，是mvc自带的生成标签字符窜的类，大家没事的时候搜一下看看具体用法。还有selectListItem这个类，主要包含键值属性和是否选中的属性 。以下代码只是根据个人思路来做的，仅供参考。

         

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Web;
using System.Web.Routing;
using System.Web.UI;

namespace System.Web.Mvc.Html
{
    public static class HtmlExtension
    {
/// <summary>
        /// 扩展radiobutton 列表
        /// </summary>
        /// <typeparam name="TModel">实体</typeparam>
        /// <typeparam name="TValue">属性</typeparam>
        /// <param name="helper"></param>
        /// <param name="expression">表达式</param>
        /// <param name="items">数据列表</param>
        /// <param name="column">每行显示个数</param>
        /// <param name="attributes">html属性</param>
        /// <returns></returns>
        public static MvcHtmlString RadioButtonListFor<TModel, TValue>(this  HtmlHelper<TModel> helper, Expression<Func<TModel, TValue>> expression, IEnumerable<SelectListItem> items, int column = 0, object attributes = null)
        {
            string raidobuttonStr = "";
            BuildListTag(out raidobuttonStr, "radio", items, expression, column, attributes);
            return MvcHtmlString.Create(raidobuttonStr);
        }

        /// <summary>
        /// 扩展radiobutton 列表
        /// </summary>
        /// <typeparam name="TModel">实体</typeparam>
        /// <typeparam name="TValue">属性</typeparam>
        /// <param name="helper"></param>
        /// <param name="expression">表达式</param>
        /// <param name="viewDataName">viewData数据列表名称</param>
        /// <param name="column">每行显示个数</param>
        /// <param name="attributes">属性</param>
        /// <returns></returns>
        public static MvcHtmlString RadioButtonListFor<TModel, TValue>(this  HtmlHelper<TModel> helper, Expression<Func<TModel, TValue>> expression, string viewDataName, int column = 0, object attributes = null)
        {
            string raidobuttonStr = "";
            var items = helper.ViewData[viewDataName] as List<SelectListItem>;
            BuildListTag(out raidobuttonStr, "radio", items, expression, column, attributes);
            return MvcHtmlString.Create(raidobuttonStr);
        }


        /// <summary>
        /// 扩展radiobutton 列表
        /// </summary>
        /// <typeparam name="TModel">实体</typeparam>
        /// <typeparam name="TValue">属性</typeparam>
        /// <param name="helper"></param>
        /// <param name="expression">表达式</param>
        /// <param name="items">数据列表</param>
        /// <param name="column">每行显示个数</param>
        /// <param name="attributes">html属性</param>
        /// <returns></returns>
        public static MvcHtmlString CheckBoxListFor<TModel, TValue>(this  HtmlHelper<TModel> helper, Expression<Func<TModel, TValue>> expression, IEnumerable<SelectListItem> items, int column = 0, object attributes = null)
        {
            string raidobuttonStr = "";
            BuildListTag(out raidobuttonStr, "checkbox", items, expression, column, attributes);
            return MvcHtmlString.Create(raidobuttonStr);
        }

        /// <summary>
        /// 扩展radiobutton 列表
        /// </summary>
        /// <typeparam name="TModel">实体</typeparam>
        /// <typeparam name="TValue">属性</typeparam>
        /// <param name="helper"></param>
        /// <param name="expression">表达式</param>
        /// <param name="viewDataName">viewData数据列表名称</param>
        /// <param name="column">每行显示个数</param>
        /// <param name="attributes">属性</param>
        /// <returns></returns>
        public static MvcHtmlString CheckBoxListFor<TModel, TValue>(this  HtmlHelper<TModel> helper, Expression<Func<TModel, TValue>> expression, string viewDataName, int column = 0, object attributes = null)
        {
            string raidobuttonStr = "";
            var items = helper.ViewData[viewDataName] as List<SelectListItem>;
            BuildListTag(out raidobuttonStr, "checkbox", items, expression, column, attributes);
            return MvcHtmlString.Create(raidobuttonStr);
        }

        /// <summary>
        /// 构造radioList或者checkBoxList标签
        /// </summary>
        /// <typeparam name="TModel"></typeparam>
        /// <typeparam name="TValue"></typeparam>
        /// <param name="raidobuttonStr">拼接的字符窜</param>
        /// <param name="tag">标签(checkbox or  radio)</param>
        /// <param name="expression">表达式</param>
        /// <param name="items">数据列表</param>
        /// <param name="column">每行显示个数</param>
        /// <param name="attributes">属性</param>
        private static void BuildListTag<TModel, TValue>(out  string raidobuttonStr, string tag, IEnumerable<SelectListItem> items, Expression<Func<TModel, TValue>> expression, int column = 0, object attributes = null)
        {
            raidobuttonStr = "";
            if (items != null && items.Any())
            {
                int count = 1;
                ///获取表达式属性名称
                var name = (expression.Body as MemberExpression).Member.Name;
                foreach (var item in items)
                {
                    TagBuilder raidobutton = new TagBuilder("input");
                    raidobutton.Attributes.Add("type", tag);
                    raidobutton.Attributes.Add("name", name);
                    raidobutton.Attributes.Add("value", item.Value);
                    if (item.Selected)
                    {
                        raidobutton.Attributes.Add("checked", "checked");
                    }
                    if (attributes != null)
                    {
                        raidobutton.MergeAttributes(new RouteValueDictionary(attributes));
                    }

                    raidobuttonStr += raidobutton.ToString(TagRenderMode.SelfClosing);
                    raidobuttonStr += item.Text;
                    raidobuttonStr += "&nbsp;&nbsp;&nbsp;";

                    if (column == 1)
                    {
                        raidobuttonStr += "<br/>";
                    }
                    ///根据每行显示个数设置换行
                    else
                    {
                        if (count == column && column != 0)
                        {
                            raidobuttonStr += "<br/>";
                        }
                    }
                    count++;
                }

            }



        }
    }
}

下面是调用的方法  

   控制器里面代码： 

       var list = new List<SelectListItem>();
            list.Add(new SelectListItem() { Text = "aaa", Value = "1", Selected = false });
            list.Add(new SelectListItem() { Text = "bbb", Value = "2", Selected = false });
            list.Add(new SelectListItem() { Text = "ccc", Value = "3", Selected = false });
            list.Add(new SelectListItem() { Text = "ddd", Value = "4", Selected = true });
            ViewBag.list = list;

  页面上的代码（两种方式）：

  （1）

 @{
    var list = ViewBag.list as List<SelectListItem>;
    
    }
@Html.CheckBoxListFor(p=>p.AccountCode,list,3)//@Html.RadioButtonListFor(p=>p.AccountCode,list,3)

 (2)

@Html.CheckBoxListFor(p=>p.AccountCode,"list",3)//@Html.RadioButtonListFor(p=>p.AccountCode,"list",3)

其中的3代表每行显示3个，可以改为其他值，默认是显示一行

大致的代码就这么多，有不懂的或者有更好想法的，可以把代码贴在回复下面。