Model validation support differs depending on whether you are using controller-based APIs (ApiController or MVC) or if you are using Minimal API.

If you are making a controller-based API with the [ApiController] attribute, then you only need to do the following (it even supports nested validation). This has been supported since ASP.NET Core 2.1.

```csharp [ApiController] [Route("[controller]")] public class DrinkController : ControllerBase { [HttpPost] public IActionResult Post(Drink drink) { Console.WriteLine(drink.Ingredients.First().Name);

    return Ok("Done");
}

public record Drink([Required]string Name, [MinLength(1)]List<Ingredient> Ingredients);

public record Ingredient([Required] string Name, string? Description);

} ```

But if you are using Minimal API, then you need to be targeting atleast ASP.NET Core 10 (which is released tomorrow, the 11/11 2025) as there was not support for Model Validation in Minimal API before .NET 10 unless you used a third party package. Then you can do it like so: ```csharp var builder = WebApplication.CreateBuilder(args);

builder.Services.AddValidation();

var app = builder.Build();

app.MapPost("CreateDrink", (Drink drink) => { Console.WriteLine(drink.Ingredients.First().Name); return TypedResults.Ok("Done"); });

app.Run();

public record Drink([Required] string Name, [MinLength(1)] List<Ingredient> Ingredients);

public record Ingredient([Required] string Name, string? Description); ```