Localize Enum Display names

src/Microsoft.AspNetCore.Mvc.Abstractions/ModelBinding/EnumGroupAndName.cs

@@ -10,8 +10,11 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
     /// </summary>
     public struct EnumGroupAndName
     {
+        private Func<string> _name;
+
         /// <summary>
-        /// Initializes a new instance of the EnumGroupAndName structure.
+        /// Initializes a new instance of the <see cref="EnumGroupAndName"/> structure. This constructor should 
+        /// not be used in any site where localization is important.
         /// </summary>
         /// <param name="group">The group name.</param>
         /// <param name="name">The name.</param>
@@ -28,7 +31,30 @@ public EnumGroupAndName(string group, string name)
             }
 
             Group = group;
-            Name = name;
+            _name = () => name;
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="EnumGroupAndName"/> structure.
+        /// </summary>
+        /// <param name="group">The group name.</param>
+        /// <param name="name">A <see cref="Func{String}"/> which will return the name.</param>
+        public EnumGroupAndName(
+            string group,
+            Func<string> name)
+        {
+            if (group == null)
+            {
+                throw new ArgumentNullException(nameof(group));
+            }
+
+            if (name == null)
+            {
+                throw new ArgumentNullException(nameof(name));
+            }
+
+            Group = group;
+            _name = name;
         }
 
         /// <summary>
@@ -39,6 +65,12 @@ public EnumGroupAndName(string group, string name)
         /// <summary>
         /// Gets the name.
         /// </summary>
-        public string Name { get; }
+        public string Name
+        {
+            get
+            {
+                return _name();
+            }
+        }
     }
 }

src/Microsoft.AspNetCore.Mvc.DataAnnotations/Internal/DataAnnotationsMetadataProvider.cs

@@ -153,15 +153,17 @@ public void CreateDisplayMetadata(DisplayMetadataProviderContext context)
                 // Dictionary does not guarantee order will be preserved.
                 var groupedDisplayNamesAndValues = new List<KeyValuePair<EnumGroupAndName, string>>();
                 var namesAndValues = new Dictionary<string, string>();
+                var enumLocalizer = _stringLocalizerFactory?.Create(underlyingType);
                 foreach (var name in Enum.GetNames(underlyingType))
                 {
                     var field = underlyingType.GetField(name);
-                    var displayName = GetDisplayName(field);
                     var groupName = GetDisplayGroup(field);
                     var value = ((Enum)field.GetValue(obj: null)).ToString("d");
 
                     groupedDisplayNamesAndValues.Add(new KeyValuePair<EnumGroupAndName, string>(
-                        new EnumGroupAndName(groupName, displayName),
+                        new EnumGroupAndName(
+                            groupName,
+                            () => GetDisplayName(field, enumLocalizer)),
                         value));
                     namesAndValues.Add(name, value);
                 }
@@ -291,18 +293,19 @@ public void CreateValidationMetadata(ValidationMetadataProviderContext context)
             }
         }
 
-        // Return non-empty name specified in a [Display] attribute for a field, if any; field.Name otherwise.
-        private static string GetDisplayName(FieldInfo field)
+        private static string GetDisplayName(FieldInfo field, IStringLocalizer stringLocalizer)
         {
             var display = field.GetCustomAttribute<DisplayAttribute>(inherit: false);
             if (display != null)
             {
-                // Note [Display(Name = "")] is allowed.
+                // Note [Display(Name = "")] is allowed but we will not attempt to localize the empty name.
                 var name = display.GetName();
-                if (name != null)
+                if (stringLocalizer != null && !string.IsNullOrEmpty(name) && display.ResourceType == null)
                 {
-                    return name;
+                    name = stringLocalizer[name];
                 }
+
+                return name ?? field.Name;
             }
 
             return field.Name;

src/Microsoft.AspNetCore.Mvc.ViewFeatures/ViewFeatures/HtmlHelper.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Text;
@@ -522,6 +523,23 @@ protected virtual IHtmlContent GenerateDisplay(
             string templateName,
             object additionalViewData)
         {
+            var modelEnum = modelExplorer.Model as Enum;
+            if (modelExplorer.Metadata.IsEnum && modelEnum != null)
+            {
+                var value = modelEnum.ToString("d");
+                var enumGrouped = modelExplorer.Metadata.EnumGroupedDisplayNamesAndValues;
+                Debug.Assert(enumGrouped != null);
+                foreach (var kvp in enumGrouped)
+                {
+                    if (kvp.Value == value)
+                    {
+                        // Creates a ModelExplorer with the same Metadata except that the Model is a string instead of an Enum
+                        modelExplorer = modelExplorer.GetExplorerForModel(kvp.Key.Name);
+                        break;
+                    }
+                }
+            }
+
             var templateBuilder = new TemplateBuilder(
                 _viewEngine,
                 _bufferScope,