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  1. public static class HTMLHelpExprettions
  2. {
  3.     private static Type GetNonNullableModelType(ModelMetadata modelMetadata)
  4.     {
  5.         Type realModelType = modelMetadata.ModelType;
  6.  
  7.         Type underlyingType = Nullable.GetUnderlyingType(realModelType);
  8.         if (underlyingType != null)
  9.         {
  10.             realModelType = underlyingType;
  11.         }
  12.         return realModelType;
  13.     }
  14.  
  15.     private static Type GetEnumTypeFromAttribute<TModel>(Expression<Func<TModel, int>> expression)
  16.     {
  17.         MemberInfo propertyInfo =
  18.             ((expression.Body as MemberExpression).Member as MemberInfo);
  19.         if (propertyInfo == null)
  20.             throw new ArgumentException("The lambda expression 'property' should point to a valid Property");
  21.         EnumDataTypeAttribute attr = Attribute.GetCustomAttribute(propertyInfo,
  22.             typeof(EnumDataTypeAttribute)) as EnumDataTypeAttribute;
  23.         if (attr == null)
  24.             throw new ArgumentException("式木で指定されたメンバーにはEnumDataTypeが指定されていません");
  25.         return attr.EnumType;
  26.     }
  27.     private static readonly SelectListItem[] SingleEmptyItem = new[] { new SelectListItem { Text = "", Value = "" } };
  28.  
  29.     //エイリアス
  30.     public static string DisplayEnumFor<TModel>(this HtmlHelper<TModel> htmlHelper,Expression<Func<TModel, int>> expression)
  31.     {
  32.         return GetEnumDescription(expression.Compile()(htmlHelper.ViewData.Model),GetEnumTypeFromAttribute(expression));
  33.     }
  34.  
  35.     private static string GetEnumDescription(int enumValue, Type enumType)
  36.     {
  37.         FieldInfo fi = enumType.GetField(enumType.GetEnumName(enumValue));
  38.  
  39.         DescriptionAttribute[] attributes = (DescriptionAttribute[])fi.GetCustomAttributes(typeof(DescriptionAttribute), false);
  40.  
  41.  
  42.         if ((attributes != null) && (attributes.Length > 0))
  43.             return attributes[0].Description;
  44.         else
  45.             return enumType.GetEnumName(enumValue);
  46.     }
  47.  
  48.     /// <summary>
  49.     /// EnumDataTypeAttributeで情報が付け加えられたint型のプロパティーをドロップダウンに変換します。
  50.     /// </summary>
  51.     /// <typeparam name="TModel"></typeparam>
  52.     /// <param name="htmlHelper"></param>
  53.     /// <param name="expression"></param>
  54.     /// <param name="model"></param>
  55.     /// <param name="htmlAttributes"></param>
  56.     /// <returns></returns>
  57.     public static MvcHtmlString EnumDropDownListFor<TModel>(
  58.         this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, int>> expression, object htmlAttributes = null)
  59.     {
  60.         ModelMetadata metadata = ModelMetadata.FromLambdaExpression(expression, htmlHelper.ViewData);
  61.         Type enumType = GetEnumTypeFromAttribute(expression);
  62.         IEnumerable<int> values = Enum.GetValues(enumType).Cast<int>();
  63.  
  64.         IEnumerable<SelectListItem> items = 
  65.             values.Select(value=>new SelectListItem
  66.             {
  67.                 Text = GetEnumDescription(value,enumType),
  68.                 Value = value.ToString(),
  69.                 Selected = value.Equals(metadata.Model)
  70.             });
  71.  
  72.         // If the enum is nullable, add an 'empty' item to the collection
  73.         if (metadata.IsNullableValueType)
  74.             items = SingleEmptyItem.Concat(items);
  75.  
  76.         return htmlHelper.DropDownListFor(expression, items, htmlAttributes);
  77.     }
  78. }
  79.  
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https://ideone.com/yUXKX
language:
C# (gmcs 5.20.1)
created:
13 years ago
visibility:
secret

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