Min API Quick Ref: Add validation support .NET 10 Prev4

Author: wadepickett

aspnetcore/fundamentals/minimal-apis.md

@@ -70,6 +70,62 @@ The <xref:System.Delegate> arguments passed to these methods are called "route h
 
 [!INCLUDE [](~/fundamentals/minimal-apis/includes/parameter-binding10.md)]
 
+## Validation support in Minimal APIs
+
+Support for validation in Minimal APIs is now available. This feature allows you to request validation of data sent to your API endpoints. Enabling validation allows the ASP.NET Core runtime to perform any validations defined on the:
+
+* Query
+* Header
+* Request body
+
+Validations are defined using attributes in the [`DataAnnotations`](xref:System.ComponentModel.DataAnnotations) namespace. Developers customize the behavior of the validation system by:
+
+* Creating custom [`[Validation]`](xref:System.ComponentModel.DataAnnotations.ValidationAttribute) attribute implementations.
+* Implementing the [`IValidatableObject`](xref:System.ComponentModel.DataAnnotations.IValidatableObject) interface for complex validation logic.
+
+If validation fails, the runtime returns a 400 Bad Request response with details of the validation errors.
+
+### Enable built-in validation support for minimal APIs
+
+Enable the built-in validation support for minimal APIs by calling the `AddValidation` extension method to register the required services in the service container for your application:
+
+```csharp
+builder.Services.AddValidation();
+```
+
+The implementation automatically discovers types that are defined in minimal API handlers or as base types of types defined in minimal API handlers. An endpoint filter performs validation on these types and is added for each endpoint.
+
+Validation can be disabled for specific endpoints by using the `DisableValidation` extension method, as in the following example:
+
+```csharp
+app.MapPost("/products",
+    ([EvenNumber(ErrorMessage = "Product ID must be even")] int productId, [Required] string name)
+        => TypedResults.Ok(productId))
+    .DisableValidation();
+```
+
+### Validation with record types
+<!-- https://github.com/dotnet/aspnetcore/pull/61193 -->
+<!-- https://github.com/dotnet/aspnetcore/pull/61402 -->
+
+Minimal APIs also support validation with C# record types. Record types can be validated using attributes from the <xref:System.ComponentModel.DataAnnotations?displayProperty=fullName> namespace, similar to classes. For example:
+
+```csharp
+public record Product(
+    [Required] string Name,
+    [Range(1, 1000)] int Quantity);
+```
+
+When using record types as parameters in Minimal API endpoints, validation attributes are automatically applied in the same way as class types:
+
+```csharp
+app.MapPost("/products", (Product product) =>
+{
+    // Endpoint logic here
+    return TypedResults.Ok(product);
+});
+``
+
 ## Responses
 
 Route handlers support the following types of return values: