Binding-Validation

Binding对数据的转换和校验案例:

前端：

<Window x:Class="Demo.ValidationRuleDemo"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="ValidationRuleDemo" Height="300" Width="300">
    <Grid>
        <StackPanel>
            <TextBox x:Name="textBox1" Margin="5"/>
            <Slider x:Name="slider1" Minimum="-10" Maximum="100" Margin="5"/>
        </StackPanel>
    </Grid>
</Window>

后台:

namespace Demo
{
    public partial class ValidationRuleDemo : Window
    {
        public ValidationRuleDemo()
        {
            InitializeComponent();

            RangeValidationRule rvr = new RangeValidationRule();
            rvr.ValidatesOnTargetUpdated = true;

            Binding binding = new Binding("Value") { Source = this.slider1 };
            binding.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
            binding.ValidationRules.Add(rvr);
            this.textBox1.SetBinding(TextBox.TextProperty, binding);//至此实现发生错误时边框变红.

            binding.NotifyOnValidationError = true;//此两句及相应委托方法实现:当错误发生时，边框变红，鼠标停留会提示“Validation Error”.
            this.textBox1.AddHandler(Validation.ErrorEvent, new RoutedEventHandler(ValidationError));
        }

        void ValidationError(object sender, RoutedEventArgs e)
        {
            if (Validation.GetErrors(this.textBox1).Count > 0)
            {
                this.textBox1.ToolTip = Validation.GetErrors(this.textBox1)[0].ErrorContent.ToString();
            }
        }
    }

    public class RangeValidationRule : ValidationRule
    {
        public override ValidationResult Validate(object value, System.Globalization.CultureInfo cultureInfo)
        {
            double d = 0;
            if (double.TryParse(value.ToString(), out d))
            {
                if (d >= 0 && d <= 100)
                {
                    return new ValidationResult(true, null);
                }
            }
            return new ValidationResult(false, "Validation Failed");
        }
    }
}