Model Validation using Data Annotations?

Short answer: Decorate model properties: public class User { [Required] [EmailAddress] public string Email { get; set; } } Automatically validated during model binding. Use ModelState.IsValid to check.

Example code

Decorate model properties: public class User { [Required] [EmailAddress] public string Email { get; set; }
} Automatically validated during model binding. Use ModelState.IsValid to check.

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.