IEnumerable转换为IList

扩展方法IEnumerable<T>转换为IList<SelectListItem> ，提供@Html.DropDownList使用

 

由于在MVC中经常会使用到@Html.DropDownList方法，而该方法接收的是List<SelectListItem> 参数，因此就想着写一个扩展方法，直接把IEnumerable转换为List<SelectListItem>类型，这样使用起来会比较方便

正式进入正文。

1、首先创建下面实体：

 //水果类

    public class Fruit

    {

        public string Code { get; set; }

        public string Name { get; set; }

        public string Color { get; set; }

    }

 

2、编写扩展方法，把IEnumerable转换为List<SelectListItem>类型，代码如下：

using System;

using System.Collections.Generic;

using System.Linq;

using System.Linq.Expressions;

using System.Text;

using System.Threading.Tasks;

using System.Web.Mvc;



namespace Common

{

    public static class Extensions

    {

        /// <summary>

        /// 扩展方法，IEnumerable<T>转换为IList<SelectListItem>

        /// </summary>

        /// <typeparam name="T"></typeparam>

        /// <param name="data">带转换的数据</param>

        /// <param name="Text"></param>

        /// <param name="Value"></param>

        /// <param name="selectValue"></param>

        /// <param name="NewItem">传递过来的SelectListItem，如请选择……</param>

        /// <returns></returns>

        public static IList<SelectListItem> ToSelectListItem<T>(this IEnumerable<T> data, Expression<Func<T, object>> Text, Expression<Func<T, object>> Value, string selectValue = "",SelectListItem NewItem=null) where T : class,new()

        {

            var list = new List<SelectListItem>();

            if (NewItem != null)

            {

                list.Add(NewItem);

            }

            string _text = "";

            string _value = "";

            if (Text.Body is MemberExpression)

            {

                MemberExpression TextMember = (MemberExpression)Text.Body;

                _text = TextMember.Member.Name;

            }

            else if (Text.Body is UnaryExpression)

            {

                UnaryExpression TextMember = (UnaryExpression)Value.Body;

                _text = (TextMember.Operand as MemberExpression).Member.Name;

            }

            if (Value.Body is MemberExpression)

            {

                MemberExpression ValueMember = (MemberExpression)Text.Body;

                _value = ValueMember.Member.Name;

            }

            else if (Value.Body is UnaryExpression)

            {

                UnaryExpression ValueMember = (UnaryExpression)Value.Body;

                _value = (ValueMember.Operand as MemberExpression).Member.Name;

            }

            var type = new T().GetType();

            var TextPropertyInfo = type.GetProperty(_text);

            var ValuePropertyInfo = type.GetProperty(_value);

            foreach (var item in data)

            {

                var selectItem = new SelectListItem() { Text = TextPropertyInfo.GetValue(item).ToString(), Value = ValuePropertyInfo.GetValue(item).ToString() };

                if (!string.IsNullOrWhiteSpace(selectValue) && selectValue == selectItem.Value)

                {

                    selectItem.Selected = true;

                }

                list.Add(selectItem);

            }



            return list;

        }



    }

3、调用方法如下：

ViewBag.Fruits = list.ToSelectListItem(it => it.Name, it => it.Color, "", new SelectListItem() { Text = "请选择水果", Value = "", Selected = true });





 @Html.DropDownList("Fruits ",ViewBag.Fruits as IList<SelectListItem>)          

 

 

 

标签:  MVC