我在我的模型中有一个属性叫做Promotion，它的类型是一个标志enum叫做UserPromotion。枚举成员的显示属性设置如下:
[Flags]
public enum UserPromotion
{
None = 0x0,
[Display(Name = "Send Job Offers By Mail")]
SendJobOffersByMail = 0x1,
[Display(Name = "Send Job Offers By Sms")]
SendJobOffersBySms = 0x2,
[Display(Name = "Send Other Stuff By Sms")]
SendPromotionalBySms = 0x4,
[Display(Name = "Send Other Stuff By Mail")]
SendPromotionalByMail = 0x8
}
现在我想要能够在我的视图中创建一个ul来显示我的Promotion属性的选定值。这就是我到目前为止所做的但问题是，我如何在这里获得显示名称?
<ul>
@foreach (int aPromotion in @Enum.GetValues(typeof(UserPromotion)))
{
var currentPromotion = (int)Model.JobSeeker.Promotion;
if ((currentPromotion & aPromotion) == aPromotion)
{
<li>Here I don't know how to get the display attribute of "currentPromotion".</li>
}
}
</ul>
更新
第一个解决方案侧重于从enum中获取显示名称。下面的代码应该是您的问题的确切解决方案。
你可以为枚举使用这个helper类:
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Reflection;
public static class EnumHelper<T>
where T : struct, Enum // This constraint requires C# 7.3 or later.
{
public static IList<T> GetValues(Enum value)
{
var enumValues = new List<T>();
foreach (FieldInfo fi in value.GetType().GetFields(BindingFlags.Static | BindingFlags.Public))
{
enumValues.Add((T)Enum.Parse(value.GetType(), fi.Name, false));
}
return enumValues;
}
public static T Parse(string value)
{
return (T)Enum.Parse(typeof(T), value, true);
}
public static IList<string> GetNames(Enum value)
{
return value.GetType().GetFields(BindingFlags.Static | BindingFlags.Public).Select(fi => fi.Name).ToList();
}
public static IList<string> GetDisplayValues(Enum value)
{
return GetNames(value).Select(obj => GetDisplayValue(Parse(obj))).ToList();
}
private static string lookupResource(Type resourceManagerProvider, string resourceKey)
{
var resourceKeyProperty = resourceManagerProvider.GetProperty(resourceKey,
BindingFlags.Static | BindingFlags.Public, null, typeof(string),
new Type[0], null);
if (resourceKeyProperty != null)
{
return (string)resourceKeyProperty.GetMethod.Invoke(null, null);
}
return resourceKey; // Fallback with the key name
}
public static string GetDisplayValue(T value)
{
var fieldInfo = value.GetType().GetField(value.ToString());
var descriptionAttributes = fieldInfo.GetCustomAttributes(
typeof(DisplayAttribute), false) as DisplayAttribute[];
if (descriptionAttributes[0].ResourceType != null)
return lookupResource(descriptionAttributes[0].ResourceType, descriptionAttributes[0].Name);
if (descriptionAttributes == null) return string.Empty;
return (descriptionAttributes.Length > 0) ? descriptionAttributes[0].Name : value.ToString();
}
}
然后你可以在视图中使用它，如下所示:
<ul>
@foreach (var value in @EnumHelper<UserPromotion>.GetValues(UserPromotion.None))
{
if (value == Model.JobSeeker.Promotion)
{
var description = EnumHelper<UserPromotion>.GetDisplayValue(value);
<li>@Html.DisplayFor(e => description )</li>
}
}
</ul>
我试着把它作为一个编辑，但它被拒绝了;我不明白为什么。
如果你用一个混合了自定义属性和普通项的Enum调用它，上面的方法会抛出一个异常。
public enum CommentType
{
All = 1,
Rent = 2,
Insurance = 3,
[Display(Name="Service Charge")]
ServiceCharge = 4
}
因此，我稍微修改了代码，以便在尝试访问自定义属性之前检查它们，如果没有找到则使用名称。
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Reflection;
public static class EnumHelper<T>
{
public static IList<T> GetValues(Enum value)
{
var enumValues = new List<T>();
foreach (FieldInfo fi in value.GetType().GetFields(BindingFlags.Static | BindingFlags.Public))
{
enumValues.Add((T)Enum.Parse(value.GetType(), fi.Name, false));
}
return enumValues;
}
public static T Parse(string value)
{
return (T)Enum.Parse(typeof(T), value, true);
}
public static IList<string> GetNames(Enum value)
{
return value.GetType().GetFields(BindingFlags.Static | BindingFlags.Public).Select(fi => fi.Name).ToList();
}
public static IList<string> GetDisplayValues(Enum value)
{
return GetNames(value).Select(obj => GetDisplayValue(Parse(obj))).ToList();
}
private static string lookupResource(Type resourceManagerProvider, string resourceKey)
{
foreach (PropertyInfo staticProperty in resourceManagerProvider.GetProperties(BindingFlags.Static | BindingFlags.NonPublic | BindingFlags.Public))
{
if (staticProperty.PropertyType == typeof(System.Resources.ResourceManager))
{
System.Resources.ResourceManager resourceManager = (System.Resources.ResourceManager)staticProperty.GetValue(null, null);
return resourceManager.GetString(resourceKey);
}
}
return resourceKey; // Fallback with the key name
}
public static string GetDisplayValue(T value)
{
var fieldInfo = value.GetType().GetField(value.ToString());
var descriptionAttributes = fieldInfo.GetCustomAttributes(
typeof(DisplayAttribute), false) as DisplayAttribute[];
if (descriptionAttributes.Any() && descriptionAttributes[0].ResourceType != null)
return lookupResource(descriptionAttributes[0].ResourceType, descriptionAttributes[0].Name);
if (descriptionAttributes == null) return string.Empty;
return (descriptionAttributes.Length > 0) ? descriptionAttributes[0].Name : value.ToString();
}
}
ASP。Net Core 3.0，这对我很有用(归功于之前的回答)。
我的Enum类:
using System;
using System.Linq;
using System.ComponentModel.DataAnnotations;
using System.Reflection;
public class Enums
{
public enum Duration
{
[Display(Name = "1 Hour")]
OneHour,
[Display(Name = "1 Day")]
OneDay
}
// Helper method to display the name of the enum values.
public static string GetDisplayName(Enum value)
{
return value.GetType()?
.GetMember(value.ToString())?.First()?
.GetCustomAttribute<DisplayAttribute>()?
.Name;
}
}
我的视图模型类:
public class MyViewModel
{
public Duration Duration { get; set; }
}
显示标签和下拉列表的剃刀视图示例。注意下拉列表不需要helper方法:
@model IEnumerable<MyViewModel>
@foreach (var item in Model)
{
<label asp-for="@item.Duration">@Enums.GetDisplayName(item.Duration)</label>
<div class="form-group">
<label asp-for="@item.Duration" class="control-label">Select Duration</label>
<select asp-for="@item.Duration" class="form-control"
asp-items="Html.GetEnumSelectList<Enums.Duration>()">
</select>
</div>
}
假设你的枚举名称是OrderState，使用以下代码:
@Html.DropDownList("selectList", new SelectList(Html.GetEnumSelectList<OrderState>(), "Value", "Text",ViewBag.selectedOrderState), new {@id="OrderState", @class = "form-control" })
在后台设置选中的选项:
var selectedOrderState = ..Data.OrderState.GetHashCode();
ViewBag.selectedOrderState = selectedOrderState;
