In this post I described the problem that by default, DataAnnotation validation doesn't recursively inspect all properties in an object for DataAnnotation attributes. There are several solutions to this problem, but in this post I used the MiniValidation library from Damian Edwards. This simple library provides a convenience wrapper around DataAnnotation validation, as well as providing features like recursive validation. Finally I showed how you can replace the built-in DataAnnotation validation with a MiniValidation-based validator

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddOptions<MySettings>()
    .BindConfiguration("MySettings")
    .ValidateMiniValidation() // 👈 Replace with mini validation
    .ValidateOnStart();

var app = builder.Build();

OptionsValidationException: 
  DataAnnotation validation failed for 'MySettings' member: 'Nested.Value' with errors: 'The Value field is required.'.; 
  DataAnnotation validation failed for 'MySettings' member: 'Nested.Count' with errors: 'The field Count must be between 1 and 100.'.
Microsoft.Extensions.Options.OptionsFactory<TOptions>.Create(string name)
Microsoft.Extensions.Options.OptionsMonitor<TOptions>+<>c__DisplayClass10_0.<Get>b__0()

For .NET Core 3.0, we’re shipping a brand new namespace called System.Text.Json with support for a reader/writer, a document object model (DOM), and a serializer. In this blog post, I’m telling you why we built it, how it works, and how you can try it. 

Over 40 hours of FREE Learning inside of this awesome collection of 8 Paths and 5 additional bonus modules.

Topics include Basic C# skills, Web API development, Blazor Apps, Static Web Apps, Xamarin and Visual Studio or VS Code 

You know that asynchronous programming makes your UI more responsive. Did you know that you can use the .NET Async tool to profile your async 
code? Diagnostics PM Sagar Shetty shows how to use this tool.  

How do callbacks, promises and async/await compare to each other? This article shows the same scenario using each of these three techniques so you can see the differences and choose which appeals most to you. 

With the latest release of ASP.NET Core, developers are wondering what the next step is for their web apps and how to convert it over to the new ASP.NET Core.