How to read the string values of multiple Language class files , Razor pages .net-core 7.0 frontend?

Question

1.Explaination

I have the login page, which is in English. I have created an Italian language class where i have inserted the public string translations.

If i want to call only the italian language values inside the class, it works flawlessly.

What i want is:

to click a button which has an asp-route-id="1" for english, or an asp-route-id="2" for italian.

After click, the page reads the english or italian language class values and shows them in the frontend.

On the backend, 'gg' is declared as an [TempData] public int gg {get; set;}.

if i declare only the: LanguageEnglishExtensions lang = new(); in the frontend, i can retrieve the class values correctly.

The same works for the Italian too, without an if{}else{} declaration.

Ps: I know that there is a solution with resources, but, to me, this seems more direct and simple to reach what i want.

2.Question

How can this be done to make it work?

3.The frontend C# code (not working)

@{

@if (gg <= 1 || gg.ToString() == null)
{
  LanguageEnglishExtensions lang = new();
}
else
{
     LanguageItalianExtensions lang = new();
}

4.The frontend Html code

 <form id="account" method="post">
 <a asp-page="/Connect" asp-route-id="1" class=" btn btn-outline-primary">
   EN
</a>

<a asp-page="/Connect" asp-route-id="2" class=" btn btn-outline-primary">
   IT
</a>
 <div asp-validation-summary="All" class="text-danger"></div>
 <div class="form-floating">
         <input asp-for="Input.Email" class="form-control" autocomplete="username" aria-required="true" />
         <label asp-for="Input.Email" class="form-label">@lang.email</label>
         <span asp-validation-for="Input.Email" class="text-danger"></span>
     </div>
     <div class="form-floating">
         <input asp-for="Input.Password" class="form-control" autocomplete="current-password" aria-required="true" style="text-align:center;" />
         <label asp-for="Input.Password" class="form-label">@lang.password</label>
         <span asp-validation-for="Input.Password" class="text-danger"></span>
     </div>
     <div class="form-group text-center">
     <br>
     <button type="submit" class="btn btn-outline-primary  border-light" >
             &ensp; @lang.login
     </button>
      </div>
 </div>

5.The Italian Language class

public  class LanguageItalianExtensions

{

public  string email = "Indirizzo email";
public  string password = "Password";
 public  string login = "Entra";

}

Answer 1

You could check the document related with localization in asp.net core

Register required services and call middleware in program.cs:

builder.Services.AddRazorPages().AddViewLocalization();
builder.Services.AddLocalization(options => options.ResourcesPath = "Resources");
var enUSCulture = "en-us";
builder.Services.Configure<RequestLocalizationOptions>(options =>
{
    var supportedCultures = new[]
    {
        new CultureInfo(enUSCulture),
        new CultureInfo("it-it")
    };
    options.DefaultRequestCulture = new RequestCulture(culture: enUSCulture, uiCulture: enUSCulture);
    options.SupportedCultures = supportedCultures;
    options.SupportedUICultures = supportedCultures;

});

....

app.UseRequestLocalization();

Add sharedresource follow this part of document:

Create a partial view to select 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-page="Index" asp-page-handler="SelectLanguage" 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>

Call the partial view in layout so that we could selct language in every page:

<div class="col-md-6 text-right">
    @await Html.PartialAsync("_SelectLanguagePartial")
</div>

Add a handler in Index page:

public IActionResult OnPostSelectLanguage(string culture, string returnUrl)
 {
     Response.Cookies.Append(
         CookieRequestCultureProvider.DefaultCookieName,
         CookieRequestCultureProvider.MakeCookieValue(new RequestCulture(culture)),
         new CookieOptions { Expires = DateTimeOffset.UtcNow.AddYears(1) }
     );

     return LocalRedirect(returnUrl);
 }

Account Page:

@inject IHtmlLocalizer<SharedResource> SharedLocalizer


 <form id="account" method="post">
    
 <div asp-validation-summary="All" class="text-danger"></div>
 <div class="form-floating">
         <input asp-for="Input.Email" class="form-control" autocomplete="username" aria-required="true" />
        <label asp-for="Input.Email" class="form-label">@SharedLocalizer["email"]</label>
         <span asp-validation-for="Input.Email" class="text-danger"></span>
     </div>
     <div class="form-floating">
         <input asp-for="Input.Password" class="form-control" autocomplete="current-password" aria-required="true" style="text-align:center;" />
        <label asp-for="Input.Password" class="form-label">@SharedLocalizer["password"]</label>
         <span asp-validation-for="Input.Password" class="text-danger"></span>
     </div>
     <div class="form-group text-center">
     <br>
     <button type="submit" class="btn btn-outline-primary  border-light" >
            @SharedLocalizer["login"]
     </button>
      </div>
 </div>
 <</form>

Result:

Upon your comment:

public class LanguageExtensions
{

    public string email ;
    public string password ;
    public string login ;
}
public class LanguageItalianExtensions : LanguageExtensions
{
    public LanguageItalianExtensions()
    {
       login= "Entra";
       email = "Indirizzo email";
       password = "Password";
    }
}
public class LanguageEnglishExtensions : LanguageExtensions
{
    public LanguageEnglishExtensions()
    {
        login = "Login";
        email = "Email";
        password = "Password";
    }
}

Page Model:

public class AccountModel : PageModel
{
    [BindProperty]
    public InputModel? Input { get; set; }
    [BindProperty]
    public LanguageExtensions lang { get; set; } = new LanguageEnglishExtensions();

    public void OnGet()
    {
    }

    public void OnGetSelectLanguage(int Id)
    {
        if(Id==2)
        {
            lang = new LanguageItalianExtensions();
        }
        else
        {
            lang = new LanguageEnglishExtensions();  
        }
    }

}

cshtml:

 <form id="account" method="post">
    <a asp-page="/Account" asp-page-handler="SelectLanguage" asp-route-id="1" class=" btn btn-outline-primary">
        EN
    </a>

    <a asp-page="/Account" asp-page-handler="SelectLanguage" asp-route-id="2" class=" btn btn-outline-primary">
        IT
    </a>
    
 <div asp-validation-summary="All" class="text-danger"></div>
 <div class="form-floating">
         <input asp-for="Input.Email" class="form-control" autocomplete="username" aria-required="true" />
        <label asp-for="Input.Email" class="form-label">@Model.lang.email</label>
         <span asp-validation-for="Input.Email" class="text-danger"></span>
     </div>
     <div class="form-floating">
         <input asp-for="Input.Password" class="form-control" autocomplete="current-password" aria-required="true" style="text-align:center;" />
        <label asp-for="Input.Password" class="form-label">@Model.lang.password</label>
         <span asp-validation-for="Input.Password" class="text-danger"></span>
     </div>
     <div class="form-group text-center">
     <br>
     <button type="submit" class="btn btn-outline-primary  border-light" >
            @Model.lang.login
     </button>
      </div>
 </div>
 <</form>

Result: