使用下拉列表绑定枚举，并在MVC C#中的get操作上设置选定值

本文关键字：操作上 get 中的 设置 MVC 下拉列表 绑定 枚举 并在 | 更新日期: 2023-09-27 18:28:33

我有一个名为CityType 的Enum

public enum CityType
    {
        [Description("Select City")]
        Select = 0,
        [Description("A")]
        NewDelhi = 1,
        [Description("B")]
        Mumbai = 2,
        [Description("C")]
        Bangalore = 3,
        [Description("D")]
        Buxar = 4,
        [Description("E")]
        Jabalpur = 5
    }

从枚举生成列表

IList<SelectListItem> list = Enum.GetValues(typeof(CityType)).Cast<CityType>().Select(x =>    new SelectListItem(){ 
    Text = EnumHelper.GetDescription(x), 
    Value = ((int)x).ToString()
}).ToList(); 
int city=0; 
if (userModel.HomeCity != null) city= (int)userModel.HomeCity;
ViewData["HomeCity"] = new SelectList(list, "Value", "Text", city);

绑定到.cshtml

@Html.DropDownList("HomeCity",null,new { @style = "width:155px;", @class = "form-control" })

EnumHelper GetDescription类以获取枚举的描述

使用下拉列表绑定枚举，并在MVC C#中的get操作上设置选定值

我在博客中谈到了这个主题，我创建了一个EnumHelper来帮助完成这个常见的任务。

http://jnye.co/Posts/4/creating-a-dropdown-list-from-an-enum-in-mvc-and-c%23

在控制器中：

//If you don't have an enum value use the type
ViewBag.DropDownList = EnumHelper.SelectListFor<MyEnum>();
//If you do have an enum value use the value (the value will be marked as selected)    
ViewBag.DropDownList = EnumHelper.SelectListFor(MyEnum.MyEnumValue);

在您的视图中：

@Html.DropDownList("DropDownList")
@* OR *@
@Html.DropDownListFor(m => m.Property, ViewBag.DropDownList as SelectList, null)

助手类：

public static class EnumHelper
{
    // Get the value of the description attribute if the   
    // enum has one, otherwise use the value.  
    public static string GetDescription<TEnum>(this TEnum value)
    {
        var fi = value.GetType().GetField(value.ToString());
        if (fi != null)
        {
            var attributes = (DescriptionAttribute[])fi.GetCustomAttributes(typeof(DescriptionAttribute), false);
            if (attributes.Length > 0)
            {
                return attributes[0].Description;
            }
        }
        return value.ToString();
    }
    /// <summary>
    /// Build a select list for an enum
    /// </summary>
    public static SelectList SelectListFor<T>() where T : struct
    {
        Type t = typeof(T);
        return !t.IsEnum ? null
                         : new SelectList(BuildSelectListItems(t), "Value", "Text");
    }
    /// <summary>
    /// Build a select list for an enum with a particular value selected 
    /// </summary>
    public static SelectList SelectListFor<T>(T selected) where T : struct
    {
        Type t = typeof(T);
        return !t.IsEnum ? null
                         : new SelectList(BuildSelectListItems(t), "Text", "Value", selected.ToString());
    }
    private static IEnumerable<SelectListItem> BuildSelectListItems(Type t)
    {
        return Enum.GetValues(t)
                   .Cast<Enum>()
                   .Select(e => new SelectListItem { Value = e.ToString(), Text = e.GetDescription() });
    }
}

这是我在下拉列表中用于枚举的代码。然后只需使用@Html.DropDown/For（）；并将此SelectList作为param放入。

public static SelectList ToSelectList(this Type enumType, string selectedValue)
    {
        var items = new List<SelectListItem>();
        var selectedValueId = 0;
        foreach (var item in Enum.GetValues(enumType))
        {
            FieldInfo fi = enumType.GetField(item.ToString());
            DescriptionAttribute[] attributes = (DescriptionAttribute[])fi.GetCustomAttributes(typeof(DescriptionAttribute), false);
            var title = "";
            if (attributes != null && attributes.Length > 0)
            {
                title = attributes[0].Description;
            }
            else
            {
                title = item.ToString();
            }
            var listItem = new SelectListItem
            {
                Value = ((int)item).ToString(),
                Text = title,
                Selected = selectedValue == ((int)item).ToString(),
            };
            items.Add(listItem);
        }
        return new SelectList(items, "Value", "Text", selectedValueId);
    }

您也可以这样扩展DropDownFor：

public static MvcHtmlString EnumDropdownListFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, Type enumType, object htmlAttributes = null)
    {
        ModelMetadata metadata = ModelMetadata.FromLambdaExpression(expression, htmlHelper.ViewData);
        SelectList selectList = enumType.ToSelectList(metadata.Model.ToString());
        return htmlHelper.DropDownListFor(expression, selectList, htmlAttributes);
    }

用法如下所示：

@Html.EnumDropdownListFor(model => model.Property, typeof(SpecificEnum))
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