How to manually validate a model with attributes?

Question

I have a class called User and a property Name

public class User {     [Required]     public string Name { get; set; } } 

And I want to validate it, and if there are any errors add to the controller's ModelState or instantiate another modelstate...

[HttpPost] public ActionResult NewUser(UserViewModel userVM) {     User u = new User();     u.Name = null;      /* something */      // assume userVM is valid     // I want the following to be false because `user.Name` is null     if (ModelState.IsValid)     {         TempData["NewUserCreated"] = "New user created sucessfully";          return RedirectToAction("Index");     }      return View(); } 

The attributes works for UserViewModel, but I want to know how to validate a class without posting it to an action.

How can I accomplish that?

Answer 1

You can use Validator to accomplish this.

var context = new ValidationContext(u, serviceProvider: null, items: null); var validationResults = new List<ValidationResult>();  bool isValid = Validator.TryValidateObject(u, context, validationResults, true);