WPF验证器 安静点

首先要确保已经安装了这个dll

xaml:

<UserControl x:Class="MyWpf.MyValid"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"  
               xmlns:local="clr-namespace:MyWpf.CommonService"
             xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
             mc:Ignorable="d" 
             d:DesignHeight="450" d:DesignWidth="800">

    <i:Interaction.Behaviors>
        <local:ValidationException></local:ValidationException>
    </i:Interaction.Behaviors>
    <Grid>
        <StackPanel>
            <TextBox Width="200"  Margin="0 20 0 0"  Height="30">
                <TextBox.Text>
                    <!-- 绑定后台Name属性，UpdateSourceTrigger="PropertyChanged"表示当属性改变的时候就立即传递到源，而不是焦点离开的时候-->
                    <Binding Path="Name" NotifyOnValidationError="True" UpdateSourceTrigger="PropertyChanged">
                        <Binding.ValidationRules>
                            <local:NotEmptyValidationRule></local:NotEmptyValidationRule>
                        </Binding.ValidationRules>

                    </Binding>
                </TextBox.Text> 
            </TextBox>
            <Button Content="提交" Width="200" Height="30"  Margin="0 20 0 0" Command="{Binding SaveCommand}"></Button>
        </StackPanel>
    </Grid>
</UserControl>

后台：

    /// <summary>
    /// MyValid.xaml 的交互逻辑
    /// </summary>
    public partial class MyValid : UserControl
    {
        public MyValid()
        {
            InitializeComponent();
            this.DataContext = new MainViewModel();
        }
    }

MainViewModel（安装mvvmlight.dll的时候自动生成的类，里面的内容需要根据实际情况改写）:

  public class MainViewModel : ViewModelBase, IValidationException
    {

        public MainViewModel()
        {
            SaveCommand = new RelayCommand(() =>
            {
                if (!IsValid)
                {
                    //如果验证未通过，则提示
                    MessageBox.Show("验证未通过");
                    return;
                }

            });
        }
        //命令必须是public
        public RelayCommand SaveCommand { get; set; }

        private bool isValid;
        public bool IsValid
        {
            get { return isValid; }
            set { isValid = value; RaisePropertyChanged(); }
        }

        private string name;
        public string Name
        {
            get { return name; }
            set { name = value; }
        }

    }

 验证器：

namespace MyWpf.CommonService
{

    public interface IValidationException
    {
        bool IsValid { get; set; }
    }


    public class ValidationException : Behavior<FrameworkElement>
    {
        //错误次数 等于0表示没有错误
        private int _count = 0;

        protected override void OnAttached()
        {
            base.OnAttached();
            this.AssociatedObject.AddHandler(Validation.ErrorEvent, new EventHandler<ValidationErrorEventArgs>(OnValidationError));
        }

        private void OnValidationError(object sender, ValidationErrorEventArgs e)
        {
            IValidationException handler = null;
            if (AssociatedObject.DataContext is IValidationException)
            {
                handler = this.AssociatedObject.DataContext as IValidationException;
            }

            if (handler == null)
            {
                return;
            }

            var element = e.OriginalSource as UIElement;
            if (element == null) return;

            if (e.Action == ValidationErrorEventAction.Added)
            {
                _count++;
            }
            else if (e.Action == ValidationErrorEventAction.Removed)
            {
                _count--;
            }

            handler.IsValid = _count == 0;
        }

        /// <summary>
        /// 解除关联的事件
        /// </summary> 
        protected override void OnDetaching()
        {
            base.OnDetaching();
            //AssociatedObject.MouseMove -= AssociatedObject_MouseMove;
            //AssociatedObject.MouseLeave -= AssociatedObject_MouseLeave;
        }


    }

    /// <summary>
    /// 实现一个不可为空的验证器
    /// </summary>
    public class NotEmptyValidationRule : ValidationRule
    {
        public override ValidationResult Validate(object value, CultureInfo cultureInfo)
        {
            return string.IsNullOrWhiteSpace((value ?? "").ToString()) ? new ValidationResult(false, "Error") : ValidationResult.ValidResult;
        }
    }

}

  结果：

  

NotifyOnValidationError="True"

 如果在源更新过程中出现验证错误时应对绑定对象引发 System.Windows.Controls.Validation.Error 附加事件，则为 true；否则为