Following this post: https://blog.bredvid.no/validating-configuration-in-asp-net-core-e9825bd15f10
I m now available to validate the Settings when a service need it. What I would like to do is to validate directly when the server starts in program.cs.
I m not sure how to do it? Is there a way to get the list of services injected in DI then verify if the type is assignable from IOption and register it?
Here is how I add to DI the Settings:
//App settings
services.ConfigureAndValidate<AuthenticationSettings>(Configuration);
services.ConfigureAndValidate<SmtpSettings>(Configuration);
The extension code:
public static class IServiceCollectionExtensions
{
public static IServiceCollection ConfigureAndValidate<T>(
this IServiceCollection serviceCollection,
IConfiguration config,
string section = null
) where T : class
{
var configType = typeof(T).Name;
if (string.IsNullOrEmpty(section)) {
section = configType;
}
return serviceCollection
.Configure<T>(config.GetSection(section))
.PostConfigure<T>(settings =>
{
var configErrors = settings.ValidationErrors().ToArray();
if (configErrors.Any())
{
var aggrErrors = string.Join(",", configErrors);
var count = configErrors.Length;
throw new ApplicationException($"Found {count} configuration error(s) in {configType}: {aggrErrors}");
}
});
}
private static IEnumerable<string> ValidationErrors(this object obj)
{
var context = new ValidationContext(obj, serviceProvider: null, items: null);
var results = new List<ValidationResult>();
Validator.TryValidateObject(obj, context, results, true);
foreach (var validationResult in results)
{
yield return validationResult.ErrorMessage;
}
}
}
Here is my current launcher:
public class Program
{
public static async Task Main(string[] args)
{
var webHost = new WebHostBuilder()
.UseKestrel()
.UseContentRoot(Directory.GetCurrentDirectory())
.ConfigureAppConfiguration((hostingContext, config) =>
{
config.AddEnvironmentVariables();
var env = hostingContext.HostingEnvironment;
config.SetBasePath(env.ContentRootPath)
.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
.AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true, reloadOnChange: true);
})
.ConfigureLogging((hostingContext, logging) =>
{
logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
logging.AddConsole();
logging.AddDebug();
})
.UseStartup<Startup>()
.Build();
using (var scope = webHost.Services.CreateScope())
{
var services = scope.ServiceProvider;
/// <---- BEGIN / AN IDEA OF WHAT I WOULD LIKE TO DO ---->
/// <---- THIS CODE IS NOT WORKING ---->
var allServices = services.GetAllServices();
if (allServices != null)
{
foreach (var service in allServices )
{
if (service.ServiceType.IsAssignableFrom(IOptions))
{
services.GetRequiredService<service.ServiceType>()
}
}
}
/// <---- END ---->
}
await webHost.RunAsync();
}
}
Let me know if you have any suggestions in comment.
Thanks for your help.
EDIT 1: Thanks Steven for your help, with your answer, it helped me to continue to find an answer, but things are still missing.
now, all my settings inherit from ISettings, like:
public class AuthenticationSettings : ISettings
{
[Required]
public string Issuer { get; set; }
[Required]
public string Audience { get; set; }
[Required]
public string SecretKey { get; set; }
[Required]
public int ExpirationDurationInDays { get; set; }
}
I update Program.cs like:
using Autofac;
using Autofac.Core;
var options = services.GetService<ILifetimeScope>()
.ComponentRegistry
.Registrations.SelectMany(e => e.Services)
.Select(s => s as TypedService)
.Where(s => s.ServiceType.IsGenericType && s.ServiceType.GetGenericTypeDefinition() == typeof(IConfigureOptions<>))
.Select(s => s.ServiceType.GetGenericArguments()[0])
.Where(s => typeof(ISettings).IsAssignableFrom(s))
.ToList();
so now I need to instantiate each option in options and get the Value. I m still working on it. let me know if you have any suggestion or the solution :)
You can get a list of configured option types by iterating the IServiceCollection
instance:
var configuredOptionTypes =
from descriptor in services
let serviceType = descriptor.ServiceType
where serviceType.IsGenericType
where serviceType.GetGenericTypeDefinition() == typeof(IConfigureNamedOptions<>)
let optionType = serviceType.GetGenericArguments()[0]
select optionType;
Following suggestions from Steven, here is my solution: My settings validator service
public SettingsValidator(
IServiceProvider services,
ILifetimeScope scope
)
{
var types = scope.ComponentRegistry.Registrations
.SelectMany(e => e.Services)
.Select(s => s as TypedService)
.Where(s => s.ServiceType.IsAssignableToGenericType(typeof(IConfigureOptions<>)))
.Select(s => s.ServiceType.GetGenericArguments()[0])
.Where(s => typeof(ISettings).IsAssignableFrom(s))
.ToList();
foreach (var t in types)
{
var option = services.GetService(typeof(IOptions<>).MakeGenericType(new Type[] { t }));
option.GetPropertyValue("Value");
}
}
in startup:
builder.RegisterType<SettingsValidator>();
example of Settings
public class AzureStorageSettings : ISettings
{
[Required]
public string ConnectionString { get; set; }
[Required]
public string Container { get; set; }
[Required]
public string Path { get; set; }
}
extensions
public static class TypeExtensions
{
public static bool IsAssignableToGenericType(this Type givenType, Type genericType)
{
foreach (var it in givenType.GetInterfaces())
{
if (it.IsGenericType && it.GetGenericTypeDefinition() == genericType)
return true;
}
if (givenType.IsGenericType && givenType.GetGenericTypeDefinition() == genericType)
return true;
Type baseType = givenType.BaseType;
if (baseType == null) return false;
return IsAssignableToGenericType(baseType, genericType);
}
}
in program.cs
using (var scope = webHost.Services.CreateScope())
{
var services = scope.ServiceProvider;
var logger = services.GetRequiredService<ILogger<Program>>();
try
{
logger.LogInformation("Starting settings validation.");
services.GetRequiredService<SettingsValidator>();
logger.LogInformation("The settings have been validated.");
}
catch (Exception ex)
{
logger.LogError(ex, "An error occurred while validating the settings.");
}
}
Let me know if it works for you too :)
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