Add custom localizer for RCL localization

League/Views/ViewLocalizer.cs

@@ -0,0 +1,154 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+// 2021-02-07: Modifications by axuno 
+
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Globalization;
+using System.IO;
+using System.Reflection;
+using System.Text;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Mvc.Controllers;
+using Microsoft.AspNetCore.Mvc.Localization;
+using Microsoft.AspNetCore.Mvc.Rendering;
+using Microsoft.AspNetCore.Mvc.ViewFeatures;
+using Microsoft.Extensions.Localization;
+
+namespace League.Views
+{
+    /// <summary>
+    /// An <see cref="IViewLocalizer"/> implementation that derives the resource location from the
+    /// assembly name the <see cref="ControllerActionDescriptor"/> belongs to.
+    /// </summary>
+    /// <remarks>
+    /// See more details on this topic:
+    /// https://terryaney.wordpress.com/2021/01/04/migrating-to-net-core-overridable-localization-in-razor-class-libraries/
+    /// </remarks>
+    public class ViewLocalizer : IViewLocalizer, IViewContextAware
+    {
+        private readonly IHtmlLocalizerFactory _localizerFactory;
+        private string _applicationName;
+        private IHtmlLocalizer _localizer;
+
+        /// <summary>
+        /// Creates a new <see cref="ViewLocalizer"/>.
+        /// </summary>
+        /// <param name="localizerFactory">The <see cref="IHtmlLocalizerFactory"/>.</param>
+        /// <param name="hostingEnvironment">The <see cref="IWebHostEnvironment"/>.</param>
+        public ViewLocalizer(IHtmlLocalizerFactory localizerFactory, IWebHostEnvironment hostingEnvironment)
+        {
+            if (hostingEnvironment == null)
+            {
+                throw new ArgumentNullException(nameof(hostingEnvironment));
+            }
+
+            _applicationName = hostingEnvironment.ApplicationName;
+
+            _localizerFactory = localizerFactory ?? throw new ArgumentNullException(nameof(localizerFactory));
+        }
+
+        /// <inheritdoc />
+        public virtual LocalizedHtmlString this[string key]
+        {
+            get
+            {
+                if (key == null)
+                {
+                    throw new ArgumentNullException(nameof(key));
+                }
+
+                return _localizer[key];
+            }
+        }
+
+        /// <inheritdoc />
+        public virtual LocalizedHtmlString this[string key, params object[] arguments]
+        {
+            get
+            {
+                if (key == null)
+                {
+                    throw new ArgumentNullException(nameof(key));
+                }
+
+                return _localizer[key, arguments];
+            }
+        }
+
+        /// <inheritdoc />
+        public LocalizedString GetString(string name) => _localizer.GetString(name);
+
+        /// <inheritdoc />
+        public LocalizedString GetString(string name, params object[] values) => _localizer.GetString(name, values);
+
+        /// <inheritdoc />
+        public IEnumerable<LocalizedString> GetAllStrings(bool includeParentCultures) =>
+            _localizer.GetAllStrings(includeParentCultures);
+
+        /// <summary>
+        /// Apply the specified <see cref="ViewContext"/>.
+        /// </summary>
+        /// <param name="viewContext">The <see cref="ViewContext"/>.</param>
+        public void Contextualize(ViewContext viewContext)
+        {
+            if (viewContext == null)
+            {
+                throw new ArgumentNullException(nameof(viewContext));
+            }
+
+            // Given a view path "/Views/Home/Index.cshtml" we want a baseName like "MyApplication.Views.Home.Index"
+            var path = viewContext.ExecutingFilePath;
+
+            if (string.IsNullOrEmpty(path))
+            {
+                path = viewContext.View.Path;
+            }
+
+            Debug.Assert(!string.IsNullOrEmpty(path), "Couldn't determine a path for the view");
+
+            #region ** Modification 2021-02-07 by axuno **
+            // To generate the path to the localization resource, the original ViewLocalizer
+            // is using the hostingEnvironment.ApplicationName.
+            // If the view is loaded from a different assembly (e.g. from a Razor Class Library),
+            // the generated path is wrong for the _localizerFactory.
+            // This is the workaround to set the applicationName to the Razor Class Library assembly:
+            if (viewContext.ActionDescriptor is ControllerActionDescriptor controllerActionDescriptor)
+            {
+                if (controllerActionDescriptor.ControllerTypeInfo.Assembly.FullName != null)
+                {
+                    var appName = new AssemblyName(controllerActionDescriptor.ControllerTypeInfo.Assembly.FullName).Name;
+                    if (appName != null) _applicationName = appName;
+                }
+            }
+            #endregion
+
+            _localizer = _localizerFactory.Create(BuildBaseName(path), _applicationName);
+        }
+
+        private string BuildBaseName(string path)
+        {
+            var extension = Path.GetExtension(path);
+            var startIndex = path[0] == '/' || path[0] == '\\' ? 1 : 0;
+            var length = path.Length - startIndex - extension.Length;
+            var capacity = length + _applicationName.Length + 1;
+            var builder = new StringBuilder(path, startIndex, length, capacity);
+
+            builder.Replace('/', '.').Replace('\\', '.');
+
+            // Prepend the application name
+            builder.Insert(0, '.');
+            builder.Insert(0, _applicationName);
+
+            return builder.ToString();
+        }
+
+        /// <inheritdoc />
+        [Obsolete("ViewLocalizer.WithCulture is no longer supported", true)]
+        public IHtmlLocalizer WithCulture(CultureInfo culture)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}