How can I use validators in ASP.NET?

How can I use validators in ASP.NET?

In ASP.NET, you can use data annotations for validation. For example, you can use attributes like [Required], [StringLength], and [Range] on your model properties.

Can you show me an example of using the [Required] attribute?

Sure! Here's a simple example:

public class UserModel {
    [Required(ErrorMessage = "Name is required.")]
    public string Name { get; set; }
}

What happens if the validation fails?

If validation fails, the model state will be invalid, and you can check this in your controller action. You can return error messages to the user.

Are there any built-in validators I should know about?

Yes, ASP.NET provides several built-in validators like [EmailAddress], [Url], and [RegularExpression] for custom patterns.