One approach could be to add a trait IValidatable<T> to your configuration classes. Then you could use Data annotations to define what should be validated and what not.
I'll provide an example on how to add a side project to your solution that would take care in the general case.
Here we have the class that we want to validate:
Configs/JwtConfig.cs
using System.ComponentModel.DataAnnotations;
using SettingValidation.Traits;
namespace Configs
{
public class JwtConfig : IValidatable<JwtConfig>
{
[Required, StringLength(256, MinimumLength = 32)]
public string Key { get; set; }
[Required]
public string Issuer { get; set; } = string.Empty;
[Required]
public string Audience { get; set; } = "*";
[Range(1, 30)]
public int ExpireDays { get; set; } = 30;
}
}
This is the "trait interface" that adds the validation capability (in c# 8 this could be changed to an interface with default methods)
SettingValidation/Traits/IValidatable.cs
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using Microsoft.Extensions.Logging;
namespace SettingValidation.Traits
{
public interface IValidatable
{
}
public interface IValidatable<T> : IValidatable
{
}
public static class IValidatableTrait
{
public static void Validate(this IValidatable @this, ILogger logger)
{
var validation = new List<ValidationResult>();
if (Validator.TryValidateObject(@this, new ValidationContext(@this), validation, validateAllProperties: true))
{
logger.LogInformation($"{@this} Correctly validated.");
}
else
{
logger.LogError($"{@this} Failed validation.{Environment.NewLine}{validation.Aggregate(new System.Text.StringBuilder(), (sb, vr) => sb.AppendLine(vr.ErrorMessage))}");
throw new ValidationException();
}
}
}
}
Once you have this, you need to add a startup filter:
SettingValidation/Filters/SettingValidationStartupFilter.cs
using System.Collections.Generic;
using Microsoft.Extensions.Logging;
using SettingValidation.Traits;
namespace SettingValidation.Filters
{
public class SettingValidationStartupFilter
{
public SettingValidationStartupFilter(IEnumerable<IValidatable> validatables, ILogger<SettingValidationStartupFilter> logger)
{
foreach (var validatable in validatables)
{
validatable.Validate(logger);
}
}
}
}
It's convention to add an extension method:
SettingValidation/Extensions/IServiceCollectionExtensions.cs
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;
using SettingValidation.Filters;
using SettingValidation.Traits;
namespace SettingValidation.Extensions
{
public static class IServiceCollectionExtensions
{
public static IServiceCollection UseConfigurationValidation(this IServiceCollection services)
{
services.AddSingleton<SettingValidationStartupFilter>();
using (var scope = services.BuildServiceProvider().CreateScope())
{
// Do not remove this call.
// ReSharper disable once UnusedVariable
var validatorFilter = scope.ServiceProvider.GetRequiredService<SettingValidationStartupFilter>();
}
return services;
}
//
// Summary:
// Registers a configuration instance which TOptions will bind against.
//
// Parameters:
// services:
// The Microsoft.Extensions.DependencyInjection.IServiceCollection to add the services
// to.
//
// config:
// The configuration being bound.
//
// Type parameters:
// TOptions:
// The type of options being configured.
//
// Returns:
// The Microsoft.Extensions.DependencyInjection.IServiceCollection so that additional
// calls can be chained.
public static IServiceCollection ConfigureAndValidate<T>(this IServiceCollection services, IConfiguration config)
where T : class, IValidatable<T>, new()
{
services.Configure<T>(config);
services.AddSingleton<IValidatable>(r => r.GetRequiredService<IOptions<T>>().Value);
return services;
}
}
}
Finally enable the usage of the startup filter
Startup.cs
public class Startup
{
public void ConfigureServices(IServiceCollection services)
{
...
services.ConfigureAndValidate<JwtConfig>(Configuration.GetSection("Jwt"));
services.UseConfigurationValidation();
...
}
}
I remember basing this code from some blog post in the internet I couldn't find right now, maybe it's the same you found, even if you don't use this solution, try refactoring what you did into a different project, so it can be reused in other ASP.NET Core solutions that you have.
