Integer validation in asp.net core

Hi Team,

I tried model validation for integer as below: where it is not working for null or empty field

1) [Required]

    public int? UsecaseID { get; set; }

2) [Range(1, int.MaxValue, ErrorMessage = "Value for {0} must be between {1} or {2} or {3}.")]
     public int UsecaseID { get; set; }

Please assist me with any other option?