ASP.NET Validation - Quick Reference Deep Knowledge : Use with technology: for validation documentation. Data Annotations FluentValidation Setup FluentValidation Patterns Validation Filter (Minimal API) Collection and Nested Validation Anti-Patterns | Anti-Pattern | Why It's Bad | Correct Approach | |--------------|--------------|------------------| | Validation in controllers | Repetitive, inconsistent | Use FluentValidation + filter | | Only client-side validation | Easily bypassed | Always validate server-side | | No async validation | Can't check DB uniqueness | Use | | Generic error mess…