在用户控件中显示验证错误

好吧,我终于想好怎么处理了。

这里需要做的是从原始绑定复制验证并将其发送到Textbox绑定。

要实现这一点,首先需要实现 INotifyDataErrorInfo 验证.GetErrors ).

    Public Event ErrorsChanged(ByVal sender As Object, ByVal e As System.ComponentModel.DataErrorsChangedEventArgs) Implements System.ComponentModel.INotifyDataErrorInfo.ErrorsChanged

Public Function GetErrors(ByVal propertyName As String) As System.Collections.IEnumerable Implements System.ComponentModel.INotifyDataErrorInfo.GetErrors
    Dim returnValue As System.Collections.IEnumerable = Nothing

    Dim errorMessage As String = Nothing


    If propertyName = "Value" Then

        If Validation.GetErrors(Me).Count = 0 Then
            errorMessage = ""
        Else
            errorMessage = Validation.GetErrors(Me).First.ErrorContent.ToString
        End If

        If String.IsNullOrEmpty(errorMessage) Then
            returnValue = Nothing
        Else
            returnValue = New List(Of String)() From {errorMessage}
        End If

    End If

    Return returnValue

End Function

Public ReadOnly Property HasErrors As Boolean Implements System.ComponentModel.INotifyDataErrorInfo.HasErrors
    Get
        Return Validation.GetErrors(Me).Any()
    End Get
End Property

下一步要做的是通知您控件它变为无效。你必须在两个地方这样做。

第一个会在 . 第二个将在 值属性ChangedCallback函数

Public Shared ValueProperty As DependencyProperty = DependencyProperty.Register("Value", GetType(String), GetType(XDateTimePicker), New PropertyMetadata(Nothing, AddressOf ValuePropertyChangedCallback))

Public Shared Sub ValuePropertyChangedCallback(ByVal dependencyObject As DependencyObject, ByVal dependencyPropertyChangedEventArgs As DependencyPropertyChangedEventArgs)
    DirectCast(dependencyObject, MyUserControl).NotifyErrorsChanged("Value")
End Sub

Private Sub MyUserControl_BindingValidationError(ByVal sender As Object, ByVal e As System.Windows.Controls.ValidationErrorEventArgs) Handles Me.BindingValidationError
    Me.NotifyErrorsChanged("Value")
End Sub

Public Sub NotifyErrorsChanged(ByVal propertyName As String)
    RaiseEvent ErrorsChanged(Me, New System.ComponentModel.DataErrorsChangedEventArgs(propertyName))
End Sub

大部分工作现在已经完成,但是您仍然需要对绑定进行一些调整。

创建文本框绑定时,需要设置 设置为False以避免原始绑定和文本框绑定之间的通知循环。 验证Nexceptions 验证数据错误 和 必须设置为True。

        Dim binding As New System.Windows.Data.Binding

    binding.Source = Me
    binding.Path = New System.Windows.PropertyPath("Value")
    binding.Mode = Data.BindingMode.TwoWay
    binding.NotifyOnValidationError = False 
    binding.ValidatesOnExceptions = True
    binding.ValidatesOnDataErrors = True
    binding.ValidatesOnNotifyDataErrors = True

    Me.TextBox1.SetBinding(TextBox.TextProperty, binding)

最后,你需要设置 和 验证说明数据错误

<uc:MyUserControl x:Name="UC" Value="{Binding Path=Value, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnNotifyDataErrors=True}" Height="20" Width="100" />

此行为是由添加的绑定级别引起的。 绑定不支持转发验证错误。

1. 用户在文本框中输入文本,并且在MyUserControl_Loaded中定义的绑定将该值传递给MyUserControl.ValueProperty。
2. 接下来,在MainPage XAML中为MyUserControl定义的绑定将值传递给模型。
3. Model.Value.set()中引发的异常由在主页XAML中设置的绑定处理。
4. 不会向与文本框关联的绑定转发异常。
5. 由于UserControl没有将ValidatesOnExceptions设置为true,因此不会显示任何视觉指示。

this.TextBox.SetBinding(TextBox.TextProperty, new Binding()
{
    Source = this.DataContext, // bind to the originating source
    Path = new PropertyPath("Value"),
    Mode = BindingMode.TwoWay,
    ValidatesOnExceptions = true,
    NotifyOnValidationError= true
});  

六个月过去了,我想知道你是否以及如何克服了这个问题。

var valueBinding = BindingOperations.GetBindingBase(this, ValueProperty);
if (valueBinding != null) TextBox.SetBinding(TextBox.TextProperty, valueBinding);

如果有人来找这个问题的好的解决方案(读:“不是用VBA编写的,而是完整的”),我会写一个 base class (虽然我只使用了外观不好看的控件进行了测试,但不知道它是否可以与 UserControl s) 基于C#中的@Theúu Blackúu Smurf的回答:

namespace MyApplication.Controls
{
    using System;
    using System.Collections;
    using System.ComponentModel;
    using System.Linq;
    using System.Windows;
    using System.Windows.Controls;
    using System.Windows.Data;

    public abstract class ControlBaseWithValidation : Control, INotifyDataErrorInfo
    {
        public ControlBaseWithValidation()
        {
            // remove the red border that wraps the whole control by default
            Validation.SetErrorTemplate(this, null);
        }

        public delegate void ErrorsChangedEventHandler(object sender, DataErrorsChangedEventArgs e);

        public event EventHandler<DataErrorsChangedEventArgs> ErrorsChanged;

        public bool HasErrors
        {
            get
            {
                var validationErrors = Validation.GetErrors(this);
                return validationErrors.Any();
            }
        }

        public IEnumerable GetErrors(string propertyName)
        {
            var validationErrors = Validation.GetErrors(this);
            var specificValidationErrors =
                validationErrors.Where(
                    error => ((BindingExpression)error.BindingInError).TargetProperty.Name == propertyName).ToList();
            var specificValidationErrorMessages = specificValidationErrors.Select(valError => valError.ErrorContent);
            return specificValidationErrorMessages;
        }

        public void NotifyErrorsChanged(string propertyName)
        {
            if (ErrorsChanged != null)
            {
                ErrorsChanged(this, new DataErrorsChangedEventArgs(propertyName));
            }
        }

        protected static void ValidatePropertyWhenChangedCallback(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
        {
            ((ControlBaseWithValidation)dependencyObject).NotifyErrorsChanged(dependencyPropertyChangedEventArgs.Property.Name);
        }
    }
}

使用 ControlBaseWithValidation 类作为无外观控件的基类,而不是 Control ValidatePropertyWhenChangedCallback 作为 PropertyChangedCallback 任何要验证的依赖项属性。