Setting the default language

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You're right, setting the default language in .NET Core requires a bit more configuration compared to .NET Framework. Here's how to achieve it for your first .NET Core web application to display validation messages in Italian:

1. Install the Localization Package:

Start by adding the Microsoft.AspNetCore.Localization NuGet package to your project. This package provides the necessary tools for localization in your .NET Core application.

2. Configure Localization Middleware:

In your Startup.cs file, locate the ConfigureServices method and add the following code to configure the localization middleware:

services.AddLocalization(options =>
{
    options.ResourcesPath = "Resources"; // Specify the folder containing resource files
});

services.AddMvc()
    .AddViewLocalization()
    .AddDataAnnotationsLocalization(); // Enable data annotation localization

This code does three things:

• Enables localization for the application.
• Sets the ResourcesPath property to indicate where your resource files will be stored. You can customize this path.
• Configures MVC to use localization for views and data annotations (validation messages).

3. Create Resource Files:

Create a folder named Resources in your project (as specified in the code). Inside this folder, create a new RESX file named ValidationMessages.it.resx (replace .it with your actual Italian language code).

4. Populate Resource Files:
Open the ValidationMessages.it.resx file. You'll see default English validation messages. Translate these messages to Italian using the built-in visual editor or text editing tools.

5. Set Default Culture (Optional):

In your Startup.cs file, locate the Configure method and add the following code to set the default culture to Italian (optional):

var supportedCultures = new[] { new CultureInfo("it-IT") };
app.UseRequestLocalization(options =>
{
    options.DefaultCulture = supportedCultures[0];
    options.SupportedCultures = supportedCultures;
    options.SupportedUICultures = supportedCultures;
});

This code sets Italian (it-IT) as the default culture and specifies that your application supports Italian for both general culture and UI culture.

Additional Notes:

• You can create resource files for other languages as needed (e.g., ValidationMessages.en.resx for English).
• For more complex scenarios, you can leverage culture providers to determine the user's preferred language dynamically.
• Refer to the official documentation for comprehensive details on localization: https://learn.microsoft.com/en-us/aspnet/core/fundamentals/localization?view=aspnetcore-8.0

With these steps, your .NET Core web application will use Italian resource files for validation messages, providing a user-friendly experience for Italian speakers.