using System.ComponentModel.DataAnnotations; namespace LibraryAPI.Models { public class Author { public long Id { get; set; } public List? Books { get; set; } [Required] public string? Country { get; set; } [Required] [StringLength(64, ErrorMessage = "Name too long")] public string? Name { get; set; } [Required] [Range(0, 2020, ErrorMessage = "Year out of valid range")] public int YearOfBirth { get; set; } [Required] public string[]? languages { get; set; } } }