Asp.Net Core XLocalizer sample startup.cs file for Razor Pages localized with XML resource files and online translation.

startup.cs

public class Startup
{    
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }
    
    // ...

    public void ConfigureServices(IServiceCollection services)
    {
        // Configure request localization
        services.Configure<RequestLocalizationOptions>(ops =>
        {
            var cultures = new CultureInfo[] { new CultureInfo("en"), new CultureInfo("tr"), new CultureInfo("ar") };
            ops.SupportedCultures = cultures;
            ops.SupportedUICultures = cultures;
            ops.DefaultRequestCulture = new Microsoft.AspNetCore.Localization.RequestCulture("en");
            ops.RequestCultureProviders.Insert(0, new RouteSegmentRequestCultureProvider(cultures));
        });

        // Regisgter traslation service
        services.AddHttpClient<ITranslator, MyMemoryTranslateService>();

        // Register XmlResourceProvider
        services.AddSingleton<IXResourceProvider, XmlResourceProvider>();

        services.AddRazorPages()
            .AddRazorPagesOptions(ops => { ops.Conventions.Insert(0, new RouteTemplateModelConventionRazorPages()); })
            // Add XLocalizer
            .AddXLocalizer<LocSource, MyMemoryTranslateService>(ops =>
            {
                ops.ResourcesPath = "LocalizationResources";
                ops.AutoAddKeys = true;
                ops.AutoTranslate = true;
                
                // Optional: Just in case you need to change the source translation culture.
                // if not provided, the default culture will be used
                ops.TranslateFromCulture = "en";
                
                // Recommended: turn on caching during production for faster localization
                ops.UseExpressMemoryCache = true; 
            });
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        // ...
        // Use request localization middleware
        app.UseRequestLocalization();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapRazorPages();
        });
    }
}