How to read appsettings.json in WPF Prism application - wpf

Question

In a pure WPF application I can use HostBuilder, like below. But how could I do the same in a Prism app? What I read, HostBuild is not possible in Prism (according to Brian Lagunas it would not make sense - cannot find the link).
Could someone point me to the right direction or share a code?
public App()
{
_host = new HostBuilder()
.ConfigureAppConfiguration((context, configurationBuilder) =>
{
configurationBuilder.SetBasePath(context.HostingEnvironment.ContentRootPath);
configurationBuilder.AddJsonFile("appsettings.json", optional: false);
})
.ConfigureServices((context, services) =>
{
services.Configure<AppSettings>(context.Configuration);
services.AddDbContext<VisitorDbContext>(options =>
options.UseSqlServer(context.Configuration.GetConnectionString("DefaultConnection")));
services.AddScoped<ISampleService, SampleService>();
services.AddScoped<IImportService, ImportService>();
services.AddSingleton<MainWindow>();
})
.ConfigureLogging(logging =>
{
//logging.AddConsole();
})
.Build();
}

Answer 1

If you use the .NET host to parse the app settings, you could override the RegisterTypes method of your Prism App.xaml.cs class to register the IOptions<T> with the app:
public partial class App : PrismApplication
{
private readonly IHost _host;
public App()
{
_host = ...;
}
...
protected override void RegisterTypes(IContainerRegistry containerRegistry)
{
containerRegistry.RegisterInstance(
_host.Services.GetService<IOptions<AppSettings>>());
}
}

Answer 2

Without using the host, this could be done like the following
public sealed partial class App
{
private readonly AppSettings? _appSettings;
public App()
{
IConfigurationBuilder configurationBuilder = new ConfigurationBuilder();
configurationBuilder.AddJsonFile("appsettings.json", optional: false);
IConfigurationRoot configuration = configurationBuilder.Build();
IServiceCollection services = new ServiceCollection();
services.Configure<AppSettings>(configuration.GetSection(typeof(AppSettings).Name));
IServiceProvider provider = services.BuildServiceProvider();
IOptions<AppSettings>? options = provider.GetService<IOptions<AppSettings>>();
if (options is null)
throw new ApplicationException("App settings is not registered");
_appSettings = options.Value;
}
protected override void RegisterTypes(IContainerRegistry containerRegistry)
{
containerRegistry.RegisterInstance(_appSettings);
}
}
you would need to add the following package
<PackageReference Include="Microsoft.Extensions.Hosting" Version="7.0.0" />
and the following namespaces
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;