WPF使用IDataErrorInfo进行数据校验

原文:WPF使用IDataErrorInfo进行数据校验

这篇博客将介绍如何使用IDataErrorInfo进行数据校验。下面直接看例子。一个Customer类，两个属性(FirstName, Age)

class Customer
{public string FirstName{get;set;}public int Age{get;set;}
}

将Customer类继承IDataErrorInfo，并实现它的属性。

    class Customer : System.ComponentModel.IDataErrorInfo{public string this[string columnName]{get{string result = string.Empty;if(columnName == "FirstName"){if(string.IsNullOrWhiteSpace(FirstName)){result = "Name cannot null or empty.";}}else if(columnName == "Age"){if(Age < 0){result = "Age cannot less then zero.";}}return result;}}public string Error{get{return null;}}public string FirstName{get;set;}public int Age{get;set;}}

在UI中绑定Customer的FirstName，Age属性，并且当出现错误数据时触发验证。

    <Window.Resources><local:Customer x:Key="CustomerInstance"  FirstName="Sam Bent" Age="24" /><ControlTemplate x:Key="TextBoxErrorTemplate"><Grid><Border BorderBrush="Blue" BorderThickness="1"><AdornedElementPlaceholder/></Border></Grid></ControlTemplate></Window.Resources><StackPanel Margin="10"><TextBox Text="{Binding Source={StaticResource CustomerInstance}, Path=FirstName, UpdateSourceTrigger=PropertyChanged, 
            ValidatesOnDataErrors=True}" ToolTip="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors)[0].ErrorContent}"Validation.ErrorTemplate="{x:Null}"Margin="0,5" /><TextBox Text="{Binding Source={StaticResource CustomerInstance}, Path=Age, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True}"
            Validation.ErrorTemplate="{StaticResource TextBoxErrorTemplate}">
            <TextBox.Style><Style TargetType="{x:Type TextBox}"><Style.Triggers><Trigger Property="Validation.HasError" Value="True"><Setter Property="Background" Value="Red" /><Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors)[0].ErrorContent}" /></Trigger></Style.Triggers></Style></TextBox.Style></TextBox></StackPanel>

将Customer的FirstName与Age属性分别绑定在两个TextBox中，设置ValidatesOnDataErrors=True来触发验证。将错误信息绑定在TextBox的ToolTip属性上，

ToolTip="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors)[0].ErrorContent}" 或者

ToolTip="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors).CurrentItem.ErrorContent}"或者

<Style TargetType="{x:Type TextBox}"><Style.Triggers><Trigger Property="Validation.HasError" Value="True"><Setter Property="Background" Value="Red" /><Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors)[0].ErrorContent}" /></Trigger></Style.Triggers>
</Style>