如果我的数据绑定失败验证，我该如何获得原始值 [英] How can i get original value if my databinding fails validation

问题描述

我有一个使用DataGrid的工作WPF对话框。 DataGrid设置为 ItemsSource = {Binding SomeCollection，Mode = TwoWay} 。此设置工作正常，我可以读取值并从UI更新它们。


稍后我加入了转换器来验证值。验证失败时显示为空。现在我有兴趣得到原始的值，以防止验证失败。

我在这里有什么选择？

解决方案

我从来没有使用转换器进行验证。相反，我使用实现IDataErrorInfo的项目，其中的数据绑定属性为ValidatesOnDataErrors = True。

使用此验证方法，保留原始值，对象返回错误值（在我的情况下是一个字符串说什么是错误）。我的视图的控件有一个自定义的验证项目，增加了一个随着时间的推移而变淡的红色边框，以及一个在鼠标悬停上弹出的工具提示。

然后你只需要把您正在显示的数据类中的验证规则：

  Private Sub OnAddress1Changed（）
 Me.RemoveError（Address1 ）
如果_Address1是Nothing OrElse _Address1.Trim =然后
 Me.AddError（Address1，请输入有效的地址行）
如果
 OnPropertyChanged（ CanShip）
 End Sub 
 
 
私有m_validationErrors作为新字典（String，String）
 Private Sub AddError（ByVal ColName As String，ByVal Msg As String ）
如果不是m_validationErrors.ContainsKey（ColName）然后
 m_validationErrors.Add（ColName，Msg）
 End If 
 End Sub 
 Private Sub RemoveError（ByVal ColName As String ）
如果m_validationErrors.ContainsKey（ColName）然后
 m_validationErrors.Remove（ColName） 
 End If 
 End Sub 
 
 
公共ReadOnly属性[错误]（）As String实现System.ComponentModel.IDataErrorInfo.Error 
获取
如果m_validationErrors.Count> 0然后
返回装运数据无效
 Else 
返回没有
结束如果
结束获取
结束属性
 
默认公共只读属性项（ByVal columnName As String）As String Implements System.ComponentModel.IDataErrorInfo.Item 
 Get 
如果m_validationErrors.ContainsKey（columnName）然后
返回m_validationErrors（columnName）.ToString 
 Else 
返回没有
结束如果
结束获取
结束属性
  

编辑

只是为了表现出来，我将给出一个示例验证模板来显示其他如何挂接它。 p>

 < Style x：Key =ToolTipValidationTargetType ={x：Type Control}> 
< Setter Property =Validation.ErrorTemplate> 
< Setter.Value> 
< ControlTemplate> 
< Border BorderBrush =RedBorderThickness =2,1,2,1> 
< AdornedElementPlaceholder /> 
< / Border> 
< / ControlTemplate> 
< /Setter.Value> 
< / Setter> 
< Style.Triggers> 
< Trigger Property =Validation.HasErrorValue =True> 
< Setter Property =ToolTipValue ={Binding（Validation.Errors）[0] .ErrorContent，RelativeSource = {x：Static RelativeSource.Self}}/> 
< / Trigger> 
< /Style.Triggers> 
< / Style> 
  

最后：
有关实施验证的MSDN文章 / a>

一个视频可以随身携带。 视频号码4

I have a working WPF dialog that uses DataGrid. The DataGrid is set to have ItemsSource={Binding SomeCollection, Mode=TwoWay}. This setup works fine, I can read values and update them from UI.

Later I have added Converters to validate values. I show blank when validation fails. Now I am interested in getting the original values back in case if validation fails.

What options do i have here?

解决方案

I have never used a converter for validation. Instead I use items that implement IDataErrorInfo with an attribute in the databinding attribute for ValidatesOnDataErrors=True.

Using this method of validation, the original value is retained, and the object returns the errors value (in my case a string saying what the error is). My View's controls have a custom validation item which adds a red border which fades over time, and a tooltip that pops up on mouse hover.

Then you just need to put your validation rules in the data classes you are displaying:

Private Sub OnAddress1Changed()
    Me.RemoveError("Address1")
    If _Address1 Is Nothing OrElse _Address1.Trim = "" Then
        Me.AddError("Address1", "Please enter a valid Address Line")
    End If
    OnPropertyChanged("CanShip")
End Sub


Private m_validationErrors As New Dictionary(Of String, String)
Private Sub AddError(ByVal ColName As String, ByVal Msg As String)
    If Not m_validationErrors.ContainsKey(ColName) Then
        m_validationErrors.Add(ColName, Msg)
    End If
End Sub
Private Sub RemoveError(ByVal ColName As String)
    If m_validationErrors.ContainsKey(ColName) Then
        m_validationErrors.Remove(ColName)
    End If
End Sub


Public ReadOnly Property [Error]() As String Implements System.ComponentModel.IDataErrorInfo.Error
    Get
        If m_validationErrors.Count > 0 Then
            Return "Shipment data is invalid"
        Else
            Return Nothing
        End If
    End Get
End Property

Default Public ReadOnly Property Item(ByVal columnName As String) As String Implements System.ComponentModel.IDataErrorInfo.Item
    Get
        If m_validationErrors.ContainsKey(columnName) Then
            Return m_validationErrors(columnName).ToString
        Else
            Return Nothing
        End If
    End Get
End Property

Edit

And just for the heck of it, I will put an example validation template in to show others how to hook it up.

<Style x:Key="ToolTipValidation" TargetType="{x:Type Control}">
                                <Setter Property="Validation.ErrorTemplate">
                                        <Setter.Value>
                                                <ControlTemplate>
                                                        <Border BorderBrush="Red" BorderThickness="2,1,2,1">
                                                                <AdornedElementPlaceholder/>
                                                        </Border>
                                                </ControlTemplate>
                                        </Setter.Value>
                                </Setter>
                                <Style.Triggers>
                                        <Trigger Property="Validation.HasError" Value="True">
                                                <Setter Property="ToolTip" Value="{Binding (Validation.Errors)[0].ErrorContent, RelativeSource={x:Static RelativeSource.Self}}"/>
                                        </Trigger>
                                </Style.Triggers>
                        </Style>

Finally: A MSDN article on implementing Validation

A video to go with it. Video number 4

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