binding validation

PacticeSolution/BindingValidationRuleSample/Validation/AgeRangeException.cs

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+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Controls;
+
+namespace BindingValidationRuleSample.Validation
+{
+    public class AgeRangeException : ValidationRule
+    {
+        public int MinAge { get; set; } = 0;
+        public int MaxAge { get; set; } = 150;
+
+        public override ValidationResult Validate(object value, CultureInfo cultureInfo)
+        {
+            int age = 0;
+            if (!int.TryParse(value.ToString(), out age))
+                return new ValidationResult(false, "Wrong value.");
+
+            if (age >= this.MinAge && age <= this.MaxAge)
+                return new ValidationResult(true, null);
+            else
+                return new ValidationResult(false, $"Valid age range is {this.MinAge}~{this.MaxAge}");
+        }
+    }
+}