dotnet-input-validation

Comprehensive input validation patterns for .NET APIs. Covers the .NET 10 built-in validation system, FluentValidation for complex business rules, Data Annotations for simple models, endpoint filters for Minimal API integration, ProblemDetails error responses, and security-focused validation techniques.

Scope

• .NET 10 built-in validation (AddValidation, ValidatableType, source generators)
• FluentValidation validators, DI registration, endpoint filters
• Data Annotations attributes, custom ValidationAttribute, IValidatableObject
• Endpoint filters for validation as a cross-cutting concern
• ProblemDetails error responses (RFC 9457)
• Security-focused validation (ReDoS prevention, allowlist, file upload)

Out of scope

• Blazor form validation (EditForm, DataAnnotationsValidator) -- see [skill:dotnet-blazor-components]
• OWASP injection prevention principles -- see [skill:dotnet-security-owasp]
• Architectural patterns for validation placement -- see [skill:dotnet-architecture-patterns]
• Options pattern ValidateDataAnnotations -- see [skill:dotnet-csharp-configuration]