class IsEvenUsingDependencyInjectionAttribute : ValidationAttribute
    {
        protected override ValidationResult? IsValid(object? value, ValidationContext validationContext)
        {
            if (value is not int number)
            {
                return new ValidationResult($"Could not validate value, values's type is {value?.GetType()}");
            }
            
            var calculator = validationContext.GetRequiredService<Calculator>();
            return calculator.IsEven(number)
                ? ValidationResult.Success
                : new ValidationResult("Value is an uneven number.");
        }
    }
    
    class Calculator
    {
        public bool IsEven(int number) => number % 2 == 0;
    }