Asp.Net Core Localized Resource in Separate Assembly

Question

I am trying to use the new Localization features of .NET Core, but outside the simple sample Microsoft has provided here, https://docs.microsoft.com/en-us/aspnet/core/fundam

Answer 1

Very late answer, but might help someone... I had a similar situation where I had to have the resource files in separate common assembly instead of having it inside the mail web/api project (Core 2.1). The reason being, I could be using the localized resources from other assemblies like Business or DAL layer for throwing warning/error/information messages. This is what I did:

Assume that my web project namespace is MyApp.Web and my resources are in separate class lib MyApp.Resources. In the resources library, create a folder (optional), say "Messages" and create a class Messages.cs. Create the resource files inside the same folder adhering to the naming conventions. For eg, Messages.fr.resx.

In the ConfigureServices method of main project, add the localization without any resource path*:

   services.AddLocalization();

   services.Configure<RequestLocalizationOptions>(
                opts =>
                {
                     /* your configurations*/
                    var supportedCultures = new List<CultureInfo>
                    {
                        new CultureInfo("en"),
                        new CultureInfo("fr")
                    };

                    opts.DefaultRequestCulture = new RequestCulture("en", "en");
                    // Formatting numbers, dates, etc.
                    opts.SupportedCultures = supportedCultures;
                    // UI strings that we have localized.
                    opts.SupportedUICultures = supportedCultures;
                });

And in the Configure method, add app.UseRequestLocalization();

In your controller, inject IStringLocalizer<Messages> localizer, where Messages is the class which you created in the Resources library. All your localized resources will be available in the localizer object, i.e., localizer["your key or default text"].

• The reason for not adding any ResourcePath in the services.AddLocalization(); options is due to the reason that both the resource files (Messages.fr.resx) and the dummy class (Messages.cs) are in the same path. The framework will check for the resource file relative to the class which we have specified in IStringLocalizer<>. So had if the Messages.cs was in the root folder of MyApp.Resources lib and the resource files were inside folder "xyz", then the configuration should be services.AddLocalization(ops => ops.ResourcesPath = "xyz");

UPDATE - Responding to the queries in the comments:

MVC Views In MVC Views, the documented approach is to use IViewLocalizer, but does not support resource sharing. So you can inject IStringLocalizer<> in the view for using the shared resources. For eg:

@inject IStringLocalizer<Messages> localizer
<h2>Information - @localizer["Shared resource access in MVC Views"]</h2>

Data Annotations In order to use shared resources in the data annotations, you can use the factory method in the service:

services.AddMvc()
          .SetCompatibilityVersion(CompatibilityVersion.Version_2_1)
          .AddDataAnnotationsLocalization(options => {
              options.DataAnnotationLocalizerProvider = (type, factory) =>
                  factory.Create(typeof(Messages));
          }); 

where the Messages in the typeof(Messages) is your shared resource dummy class.