using System.Globalization; using System.IO; using System.Windows.Controls; namespace VBASync.WPF { public class FilePathValidationRule : ValidationRule { public override ValidationResult Validate(object value, CultureInfo cultureInfo) => new ValidationResult(string.IsNullOrEmpty(value as string) || File.Exists(value as string), null); } public class FolderPathValidationRule : ValidationRule { public override ValidationResult Validate(object value, CultureInfo cultureInfo) => new ValidationResult(string.IsNullOrEmpty(value as string) || Directory.Exists(value as string), null); } }