验证之 IDataErrorInfo 简单 Demo

public class AgeInfoWithValidation : IDataErrorInfo
{
        public int Age { get; set; }

        public string this[string columnName] {
        get {
            if (columnName == "Age") 
                return Age < 18 ? $"年龄：{Age},未成年" : null; 
            return null;
        }
    }
    public string Error => throw new NotImplementedException();
}

<StackPanel>
    <StackPanel.DataContext>
        <local:AgeInfoWithValidation/>
    </StackPanel.DataContext>
    <Slider x:Name="age" Minimum="0" Maximum="100" Value="{Binding Age, UpdateSourceTrigger=PropertyChanged}" />
    <Label >
        <Label.Content>
            <Binding Path="Age">
                <Binding.ValidationRules>
                    <DataErrorValidationRule/>
                </Binding.ValidationRules>
            </Binding>
        </Label.Content>
    </Label>
</StackPanel>