Localization Services and Configuration in ASP.NET Core

This documentation page explains how to set up localization services and configuration in an ASP.NET Core application. The goal is to create a basic website that supports multiple cultures.

Services

CultureInfoSettings

CultureInfoSettings is a class that represents the culture settings of your application. It includes the default culture and a list of supported cultures. These settings are loaded from the appsettings.json file.

public class CultureInfoSettings
{
    public string DefaultCulture { get; set; }
    public List<System.Globalization.CultureInfo> SupportedCultures { get; set; }
}

JsonStringLocalizerFactory

JsonStringLocalizerFactory is a factory that creates instances of JsonStringLocalizer. It uses IDistributedCache to cache localized strings and CultureInfoSettings to get the current culture.

public class JsonStringLocalizerFactory : IStringLocalizerFactory
{
    public IStringLocalizer Create(Type resourceSource) =>
        new JsonStringLocalizer(cache, cultureInfoSettings);

    public IStringLocalizer Create(string baseName, string location) =>
        new JsonStringLocalizer(cache, cultureInfoSettings);
}

JsonStringLocalizer

JsonStringLocalizer is a class that provides localized strings. It uses IDistributedCache to cache localized strings and CultureInfoSettings to get the current culture.

public class JsonStringLocalizer : IStringLocalizer
{
    // Implementation details...
}

Configuration

In the Program.cs file, you configure your application to use these services.

First, you load the CultureInfoSettings from the appsettings.json file and register it in the DI container.

builder.Services.Configure<CultureInfoSettings>(builder.Configuration.GetSection("CultureInfoSettings"));
builder.Services.AddSingleton(resolver => resolver.GetRequiredService<IOptions<CultureInfoSettings>>().Value);

Then, you configure the RequestLocalizationOptions to use the CultureInfoSettings.

builder.Services.Configure<RequestLocalizationOptions>(options =>
{
    var supportedCultures = cultureInfoSettings.SupportedCultures;
    options.DefaultRequestCulture = new RequestCulture(cultureInfoSettings.DefaultCulture);
    options.SupportedCultures = supportedCultures;
    options.SupportedUICultures = supportedCultures;
});

Finally, you register the LocalizationMiddleware and JsonStringLocalizerFactory in the DI container.

builder.Services.AddSingleton<LocalizationMiddleware>();
builder.Services.AddSingleton<IStringLocalizerFactory, JsonStringLocalizerFactory>();

Now, your application is ready to support multiple cultures. The LocalizationMiddleware will set the current culture for each request based on the Accept-Language HTTP header, and the JsonStringLocalizer will provide localized strings based on the current culture.

Sure, here's how localization is implemented on the Index page in your ASP.NET Core application.

Implementation on Index Page

The Index page uses the IStringLocalizer<T> interface to localize text. IStringLocalizer<T> is injected into the view using the @inject directive, and then the ["key"] indexer is used to get localized strings.

Here's an example of how you might use IStringLocalizer<T> in your Index page:

@page
@model IndexModel
@inject Microsoft.Extensions.Localization.IStringLocalizer<IndexModel> loc


<h1>Country</h1>
<p><strong>@loc["CountryId"]:</strong> @Model.CountryId</p>
<p><strong>@loc["CountryCode"]:</strong> @Model.CountryCode</p>
<p><strong>@loc["CountryName"]:</strong> @Model.CountryName</p>
<p><strong>@loc["Latitude"]:</strong> @Model.Latitude</p>
<p><strong>@loc["Longitude"]:</strong> @Model.Longitude</p>

In this example, "Welcome", "WelcomeText", "Country", "CountryId", "CountryCode", "CountryName", "Latitude", and "Longitude" are keys that correspond to entries in your resource files. The actual text that gets displayed will depend on the current culture.

The resource files should be named MyFile.en-US.resx, MyFile.es-ES.resx, etc., and placed in the Resources folder. Each resource file should contain entries for "Welcome", "WelcomeText", "Country", "CountryId", "CountryCode", "CountryName", "Latitude", and "Longitude".

When a user visits the Index page, the text that gets displayed will be localized according to the current culture. If the current culture is "en-US", the user will see the English version of the text. If the current culture is "es-ES", the user will see the Spanish version of the text.