在Silverlight应用程序中进行数据验证

实例

首先我们编写一个简单的业务类，由于数据绑定验证只能在双向绑定中，所以这里需要实现INotifyPropertyChanged接口，如下代码所示，在set设置器中我们对于数据的合法性进行检查，如果不合法则抛出一个异常：

/// <summary>
/// Author:TerryLee
/// http://www.cnblogs.com/Terrylee
/// </summary>
public class Person : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;
    private int _age;
    public int Age
    {
        get { return _age; }
        set {
            if (value < 0)
                throw new Exception("年龄输入不合法！");
            _age = value;
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs("Age"));
            }
        }
    }

    private String _name = "Terry";
    public String Name
    {
        get { return _name; }
        set {
            if (value.Length < 4)
                throw new Exception("姓名输入不合法！");
            _name = value;
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs("Name"));
            }

        }
    }

    public void NotifyPropertyChanged(String propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

编写数据绑定，如下代码所示，设置NotifyOnValidationError和ValidatesOnExceptions属性为true，并且定义BindingValidationError事件：

<!--
    http://www.cnblogs.com/Terrylee
-->
<StackPanel Orientation="Horizontal" Margin="10">
    <TextBox x:Name="txtName"  Width="200" Height="30"
            Text="{Binding Name,Mode=TwoWay,
            NotifyOnValidationError=true,
            ValidatesOnExceptions=true}"
            BindingValidationError="txtName_BindingValidationError">
    </TextBox>
    <my:Message x:Name="messageName"></my:Message>
</StackPanel>
<StackPanel Orientation="Horizontal" Margin="10">
    <TextBox x:Name="txtAge" Width="200" Height="30"
            Text="{Binding Age,Mode=TwoWay,
            NotifyOnValidationError=true,
            ValidatesOnExceptions=true}"
            BindingValidationError="txtAge_BindingValidationError">
    </TextBox>
    <my:Message x:Name="messageAge"></my:Message>
</StackPanel>

实现BindingValidationError事件，在这里可以根据ValidationErrorEventAction来判断如何进行处理，在界面给出相关的提示信息等，如下代码所示：

/// <summary>
/// Author:TerryLee
/// http://www.cnblogs.com/Terrylee
/// </summary>
void txtAge_BindingValidationError(object sender, ValidationErrorEventArgs e)
{
    if (e.Action == ValidationErrorEventAction.Added)
    {
        messageAge.Text = e.Error.Exception.Message;
        messageAge.Validation = false;
    }
    else if (e.Action == ValidationErrorEventAction.Removed)
    {
        messageAge.Text = "年龄验证成功";
        messageAge.Validation = true;
    }
}