WPF 验证
<div id="cnblogs_post_body">目录：1、ValidationRule 验证
2、Exception 验证
3、IDataErrorInfo 验证
4、Custom Control 验证
1、ValidationRule 验证
ValidationRule：是通过ValidationRule中的的Validate方法来验证我们绑定的属性。所以我们的用法是继承ValidationRule，重写他的Validate方法。示例
public class RequiredRule : ValidationRule { public override ValidationResult Validate(object value, CultureInfo cultureInfo) { if (value == null) return new ValidationResult(false, "不能为空值！"); if (string.IsNullOrEmpty(value.ToString())) return new ValidationResult(false, "不能为空字符串！"); return new ValidationResult(true, null); } }而XAML中需要把错误信息显示出来。
<Window.Resources> <ControlTemplate x:Key="ErrorTemplate"> <Border BorderBrush="Red" BorderThickness="1"> <AdornedElementPlaceholder/> </Border> </ControlTemplate> <Style TargetType="TextBox"> <Setter Property="Validation.ErrorTemplate" Value="{StaticResource ErrorTemplate}"> </Setter> <Style.Triggers> <Trigger Property="Validation.HasError" Value="True"> <Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors).ErrorContent}"/> </Trigger> </Style.Triggers> </Style> </Window.Resources> <StackPanel> <TextBlock Text="姓名"/> <TextBox> <TextBox.Text> <Binding Path="Name" UpdateSourceTrigger="PropertyChanged" ValidatesOnDataErrors="True"> <Binding.ValidationRules> <ValidationRules:RequiredRule/> </Binding.ValidationRules> </Binding> </TextBox.Text> </TextBox> <TextBlock Text="年龄"/> <TextBox > <TextBox.Text> <Binding Path="Age" UpdateSourceTrigger="PropertyChanged" ValidatesOnDataErrors="True"> <Binding.ValidationRules> <ValidationRules:GreaterThanRule Number="10"/> </Binding.ValidationRules> </Binding> </TextBox.Text> </TextBox> </StackPanel>这样显示的错误信息就会以 ToolTip和红色边框的形式显示出来。但这边如果又在TextBox里面设置ToolTip那么就会优先选择TextBox里的，也就是Style中的ToolTip遇到错误信息是不会显示出来的，而是显示TextBox中的ToolTip。所以我们可以改善一下显示的模版来解决这个问题。
<ControlTemplate x:Key="ErrorTemplate"> <DockPanel LastChildFill="true"> <Border Background="Red" DockPanel.Dock="right" Margin="5,0,0,0" Width="20" Height="20" CornerRadius="10" ToolTip="{Binding ElementName=customAdorner, Path=AdornedElement.(Validation.Errors).ErrorContent}"> <TextBlock Text="!" VerticalAlignment="center" HorizontalAlignment="center" FontWeight="Bold" Foreground="white"> </TextBlock> </Border> <AdornedElementPlaceholder Name="customAdorner" VerticalAlignment="Center" > <Border BorderBrush="red" BorderThickness="1" /> </AdornedElementPlaceholder> </DockPanel> </ControlTemplate>2、Exception 验证
Exception ：我们xaml中绑定的对象是属性。所以Exception验证，就是通过属性的改变来判断是否正常。如：
public int Age { get { return _age; } set { if (value > 200) { throw new Exception("年龄不能大于200"); } _age = value; } }同样跑出的异常在Xaml中也要显示下。XAML同上。这种方式就会破坏POCO的设计原则。
3、IDataErrorInfo 验证
IDataErrorInfo：这个验证是通过我们的实体对象继承IDataErrorInfo来实现的。这里声明的this索引器来访问类的成员。
public class BaseDataErrorInfo : IDataErrorInfo { private string _error; public string this { get { return GetErrorFor(columnName); } } public string Error { get { return _error; } set { _error = value; } } public virtual string GetErrorFor(string columnName) { return string.Empty; } }public class Person : BaseDataErrorInfo { public string Name { get; set; } public override string GetErrorFor(string columnName) { if (columnName == "Name") if (string.IsNullOrEmpty(Name)) return "Name 不能为空"; return base.GetErrorFor(columnName); } }XAML同上。
4、Custom Control 验证
这里我即不想污染实体类，又想实现一个通用的Validate。我想通过我xaml绑定的属性和它所属的控件。来显示ToolTip。
public abstract class Validator : FrameworkElement { static Validator() { DefaultStyleKeyProperty.OverrideMetadata(typeof(Validator), new FrameworkPropertyMetadata(typeof(Validator))); } public virtual string ErrorMessage { get { return string.Empty; } } public abstract bool InitialValidation(); public FrameworkElement ElementName { get { return (FrameworkElement)GetValue(ElementNameProperty); } set { SetValue(ElementNameProperty, value); } } // Using a DependencyProperty as the backing store for ElementName.This enables animation, styling, binding, etc... public static readonly DependencyProperty ElementNameProperty = DependencyProperty.Register("ElementName", typeof(FrameworkElement), typeof(Validator), new PropertyMetadata(null)); public object Source { get { return (object)GetValue(SourceProperty); } set { SetValue(SourceProperty, value); } } // Using a DependencyProperty as the backing store for Source.This enables animation, styling, binding, etc... public static readonly DependencyProperty SourceProperty = DependencyProperty.Register("Source", typeof(object), typeof(Validator), new UIPropertyMetadata(new PropertyChangedCallback(ValidPropertyPropertyChanged))); private static void ValidPropertyPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { var validator = d as Validator; if (validator != null) validator.SetSourceFromProperty(); if (string.IsNullOrEmpty(e.NewValue.ToString())) { if (validator != null) { validator.IsValid = validator.InitialValidation(); if (validator.ElementName.DataContext != null) validator.ShowToolTip(); validator.IsValid = false; } } } private void ShowToolTip() { if (IsValid) { timer = new DispatcherTimer(); timer.Interval = TimeSpan.FromSeconds(1.5); _toolTip = new ToolTip(); _toolTip.StaysOpen = true; _toolTip.PlacementTarget = ElementName; _toolTip.Placement = PlacementMode.Right; _toolTip.Content = ErrorMessage; _toolTip.IsOpen = true; timer.Tick += (sender, args) => { _toolTip.IsOpen = false; timer.Stop(); }; timer.Start(); } } private void SetSourceFromProperty() { var expression = this.GetBindingExpression(SourceProperty); if (expression != null && this.ElementName == null) this.SetValue(Validator.ElementNameProperty, expression.DataItem as FrameworkElement); } private ToolTip _toolTip; private DispatcherTimer timer; public bool IsValid { get; set; } }这是一个简单的Validate基类。提供思想。功能不完善。
然后继承这个Validator
public class RequiredValidator : Validator { public override string ErrorMessage { get { return "不能为空值"; } } public override bool InitialValidation() { if (Source == null) return false; return string.IsNullOrEmpty(Source.ToString()); } }这里ErrorMessage是显示错误信息。
InitialValidation方法是我们要验证的规则。
代码
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