dotnet-input-validation
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 boundary: This skill owns practical validation framework guidance -- when to use each framework, how to configure and integrate them, and security-focused input handling tips. OWASP security principles (injection categories, threat modeling) -- see [skill:dotnet-security-owasp]. Architectural validation strategy (where validation fits in clean architecture, vertical slices) -- see [skill:dotnet-architecture-patterns]. Options pattern validation with ValidateDataAnnotations() -- see [skill:dotnet-csharp-configuration].
Out of scope: Blazor form validation (EditForm, DataAnnotationsValidator) -- see [skill:dotnet-blazor-auth]. 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].
Cross-references: [skill:dotnet-security-owasp] for OWASP injection prevention, [skill:dotnet-architecture-patterns] for architectural validation strategy, [skill:dotnet-minimal-apis] for Minimal API pipeline integration, [skill:dotnet-csharp-configuration] for Options pattern validation.
Validation Framework Decision Tree
Choose the validation framework based on project requirements:
- .NET 10 Built-in Validation (
AddValidation) -- default for new .NET 10+ projects. Source-generator-based, AOT-compatible, auto-discovers types from Minimal API handlers. Best for: greenfield projects targeting .NET 10+. - FluentValidation -- when validation rules are complex (cross-property, conditional, database-dependent). Rich fluent API with testable validator classes. Best for: complex business rules, domain validation.
- Data Annotations -- when models need simple declarative validation (
[Required],[Range]). Widely understood, works with MVC model binding andIValidatableObjectfor cross-property checks. Best for: simple DTOs, shared models.
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