How can I add manual localization to my .NET Core MVC app?

Question

I am trying to add the option to choose from two languages: Bulgarian and English. I am using the Microsoft.Localization Nuget package and I have added two resource files: Resources/Views/Home/Landing.bg-BG.resx and Landing.en-US.resx however when I try to change the language and redirect to the Landing page it doesn't do anything.

My Program.cs:

using Market.Services;
using Market.Services.Firebase;
using Market.Services.Inventory;
using Market.Services.Offers;
using Market.Services.Orders;
using Market.Services.Reviews;
using Microsoft.AspNetCore.Authentication.Cookies;
using Market.Data;
using Microsoft.AspNetCore.Identity;
using Microsoft.EntityFrameworkCore;
using Market.Data.Models;
using Microsoft.AspNetCore.Builder;
using Market.Services.Authentication;
using Microsoft.AspNetCore.Mvc.Razor;
using Microsoft.AspNetCore.Localization;
using System.Globalization;
using Microsoft.Extensions.Options;

var cookiePolicyOptions = new CookiePolicyOptions
{
    MinimumSameSitePolicy = SameSiteMode.Strict,
};

var builder = WebApplication.CreateBuilder(args);
// Add services to the container.
builder.Services.AddControllersWithViews()
     .AddViewLocalization(LanguageViewLocationExpanderFormat.Suffix);
builder.Services.AddHttpClient();

builder.Services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme)
    .AddCookie(options =>
    {
        options.ExpireTimeSpan = TimeSpan.FromMinutes(20);
        options.SlidingExpiration = true;
        options.AccessDeniedPath = "/Forbidden/";
    });

builder.Services.AddLocalization(options => options.ResourcesPath = "Resources");
builder.Services.Configure<RequestLocalizationOptions>(options =>
{
    var supportedCultures = new[]
                {
                    new CultureInfo("bg-BG"),
                    new CultureInfo("en-US"),
                };

    options.DefaultRequestCulture = new RequestCulture(culture: "bg-BG", uiCulture: "bg-BG");

    options.SupportedCultures = supportedCultures;
    options.SupportedUICultures = supportedCultures;
});

builder.Services.AddHttpContextAccessor();

builder.Services.AddScoped<IAuthenticationService, AuthenticationService>();
builder.Services.AddScoped<IUserService, UserService>();
builder.Services.AddScoped<IInventoryService, InventoryService>();
builder.Services.AddScoped<IOfferService, OfferService>();
builder.Services.AddScoped<IFirebaseServive, FirebaseService>();
builder.Services.AddScoped<IOrdersService, OrdersService>();
builder.Services.AddScoped<IReviewsService, ReviewsService>();

var app = builder.Build();

app.UseRequestLocalization();
app.UseRequestLocalization(new RequestLocalizationOptions
{
    ApplyCurrentCultureToResponseHeaders = true,
    CultureInfoUseUserOverride = false
});


// Configure the HTTP request pipeline.
if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Home/Error");
    // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
    app.UseHsts();
}

app.UseHttpsRedirection();

app.UseStaticFiles();
app.UseCookiePolicy(cookiePolicyOptions);

app.UseRouting();

app.UseAuthentication();
app.UseAuthorization();

app.MapControllerRoute(
    name: "default",
    pattern: "{controller=Home}/{action=Index}/{id?}");

app.Run();

My _ToggleLanguage used to choose a language:

@using Microsoft.AspNetCore.Builder
@using Microsoft.AspNetCore.Http.Features
@using Microsoft.AspNetCore.Localization
@using Microsoft.AspNetCore.Mvc.Localization
@using Microsoft.Extensions.Options

@inject IViewLocalizer Localizer
@inject IOptions<RequestLocalizationOptions> LocOptions

@{
    var requestCulture = Context.Features.Get<IRequestCultureFeature>();
    var cultureItems = LocOptions.Value.SupportedUICultures
        .Select(c => new SelectListItem { Value = c.Name, Text = c.DisplayName })
        .ToList();
    var returnUrl = string.IsNullOrEmpty(Context.Request.Path) ? "~/" : $"~{Context.Request.Path.Value}";
}

<div title="@Localizer["Request culture provider:"] @requestCulture?.Provider?.GetType().Name">
    <form id="selectLanguage" asp-controller="Home"
          asp-action="SetLanguage" asp-route-returnUrl="@returnUrl"
          method="post" class="form-horizontal" role="form">
        <label asp-for="@requestCulture.RequestCulture.UICulture.Name">@Localizer["Language:"]</label> <select name="culture"
                                                                                                               onchange="this.form.submit();"
                                                                                                               asp-for="@requestCulture.RequestCulture.UICulture.Name" asp-items="cultureItems">
        </select>
    </form>
</div>

My method for setting the language ( Home/SetLanguage ):

[HttpPost]
public IActionResult SetLanguage(string culture, string returnUrl)
{
    Response.Cookies.Append(
        CookieRequestCultureProvider.DefaultCookieName,
        CookieRequestCultureProvider.MakeCookieValue(new RequestCulture(culture)),
        new CookieOptions { Expires = DateTimeOffset.UtcNow.AddMinutes(2) } //increase time
    );

    return LocalRedirect(returnUrl);
}

Answer 1

The reason why your codes not working is , you don't pass the right RequestLocalizationOptions to the app.UseRequestLocalization middleware and you use two middelware at the program.cs.

Please try below codes and it should work well.

1.Modify the requestoption to set the CookierequestCultureProvider firstly.

builder.Services.Configure<RequestLocalizationOptions>(options =>
{
    var supportedCultures = new[]
                {
                    new CultureInfo("bg-BG"),
                    new CultureInfo("en-US"),
                };
     options.DefaultRequestCulture = new RequestCulture(culture: "bg-BG", uiCulture: "bg-BG");

    options.SupportedCultures = supportedCultures;
    options.SupportedUICultures = supportedCultures;
    var questStringCultureProvider = options.RequestCultureProviders[0];
    options.RequestCultureProviders.RemoveAt(0);
    options.RequestCultureProviders.Insert(1, questStringCultureProvider);
});

2.Update the UseRequestLocalization as below：

var app = builder.Build();
var locOptions = app.Services.GetService<IOptions<RequestLocalizationOptions>>();
app.UseRequestLocalization(locOptions.Value);
 ...

Result: