添加项目文件。

Sai.Toolkit.Mvvm/Attributes/IsNumericAttribute.cs

@@ -0,0 +1,12 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace Sai.Toolkit.Mvvm.Attributes;
+
+[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field | AttributeTargets.Parameter)]
+public sealed class IsNumericAttribute : ValidationAttribute
+{
+    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
+    {
+        return double.TryParse(value.ToString(), out var _) ? ValidationResult.Success : new("输入内容不是数值。");
+    }
+}