所以我必须承认,当我写这篇文章的时候,我有一个可行的答案,但是花了很长时间才弄明白,所以我在这里发布它,希望它能帮助别人,即使它是一个非常具体的场景。
我为我的应用程序使用MVVM模型,所以我不想在xaml页面后面有代码。我还想要一种方法将文本框绑定到IDataErrorInfo属性,其中通过文本框的lostfocus事件触发对该文本框的验证。此事件将绑定到视图模型上的中继命令,该命令将验证适用的对象并添加实际的错误。
所以我需要有文本框lostfocus eventcommand将文本框名称(与数据库中的列名匹配)作为命令参数。
这里是什么,我试图完成
下面的屏幕截图是我是如何做的:
Imports GalaSoft.MvvmLight.Command
Private _LostFocusValidateCommand As RelayCommand(Of String)
Public ReadOnly Property LostFocusValidateCommand() As RelayCommand(Of String)
Get
If _LostFocusValidateCommand Is Nothing Then
_LostFocusValidateCommand = New RelayCommand(Of String)(AddressOf LostFocusValidateExecute)
End If
Return _LostFocusValidateCommand
End Get
End Property
Private Sub LostFocusValidateExecute(sParam As String)
NewClient.PropertyValitaion(False, sParam)
End Sub
:
首先,我在视图模型中定义的命令
这里是使用IDataErrorInfo的属性验证(我遗漏了他IDataErrorInfo的基本实现来节省空间,如果你想让我发布它,留下评论)
Public Sub PropertyValitaion(bAllProperties As Boolean, Optional sProperty As String = "")
'initialize validation helper
Dim vhelper As New ValidationHelper
If bAllProperties Or sProperty = "chrCompany" Then
If String.IsNullOrEmpty(chrCompany) Then
AddError("chrCompany", "You must enter a Company Name")
Else
RemoveError("chrCompany")
End If
End If
If bAllProperties Or sProperty = "chrFirst" Then
If String.IsNullOrEmpty(chrFirst) Then
AddError("chrFirst", "You must enter a First Name")
Else
RemoveError("chrFirst")
End If
End If
If bAllProperties Or (sProperty = "chrPhone1" Or sProperty = "chrPhone1Ext") Then
If String.IsNullOrEmpty(Trim(chrPhone1Ext)) = False And String.IsNullOrEmpty(Trim(chrPhone1)) Then
Me.AddError("chrPhone1", "Provide a phone number or remove extension")
Else
RemoveError("chrPhone1")
End If
If String.IsNullOrEmpty(Trim(chrPhone1)) = False Then
If vhelper.CheckPhoneNumber(Me.chrPhone1) = False Then
Me.AddError("chrPhone1", "Phone 1 format invalid")
Else
RemoveError("chrPhone1")
End If
End If
End If
End Sub
困难的部分是搞清楚如何定义样式。风格很长,对不起,“可读”xml的乐趣:
<Style x:Key="FTC_ValidateTextBox" BasedOn="{x:Null}" TargetType="{x:Type TextBox}">
<Style.Setters>
<Setter Property="FontFamily" Value="Open Sans Condensed"/>
<Setter Property="FontSize" Value="19" />
<Setter Property="Margin" Value="3,3,15,6"/>
<Setter Property="Padding" Value="10,3"/>
<Setter Property="TextWrapping" Value="Wrap" />
<Setter Property="HorizontalAlignment" Value="Stretch" />
<Setter Property="VerticalAlignment" Value="Center" />
<Setter Property="Background" Value="{StaticResource DetailTextBox}" />
<Setter Property="BorderBrush" Value="{StaticResource MediumGray}" />
<Setter Property="BorderThickness" Value="1" />
<Setter Property="Foreground" Value="Black" />
<Setter Property="AllowDrop" Value="true"/>
<Setter Property="FocusVisualStyle" Value="{x:Null}"/>
<Setter Property="ScrollViewer.PanningMode" Value="VerticalFirst"/>
<Setter Property="Stylus.IsFlicksEnabled" Value="False"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TextBox}">
<Border Name="Bd" SnapsToDevicePixels="true" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}">
<ScrollViewer x:Name="PART_ContentHost" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="LostFocus">
<cmd:EventToCommand Command="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}},Path=DataContext.LostFocusValidateCommand}"
CommandParameter="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type TextBox}},Path=Name}"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</ScrollViewer>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Background" TargetName="Bd" Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}"/>
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
<Setter Property="Validation.ErrorTemplate">
<Setter.Value>
<ControlTemplate>
<Border BorderBrush="{StaticResource MediumRed}" >
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<AdornedElementPlaceholder Name="parentTextBox" />
<TextBlock Grid.Row="1" Style="{StaticResource FTC_DetailError}"
Text="{Binding ElementName=parentTextBox, Path=AdornedElement.(Validation.Errors).CurrentItem.ErrorContent}"/>
</Grid>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style.Setters>
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="true">
<Setter Property="ToolTip" Value="{Binding RelativeSource={x:Static RelativeSource.Self}, Path=(Validation.Errors).CurrentItem.ErrorContent}"/>
<Setter Property="BorderBrush" Value="{StaticResource MediumRed}"/>
<Setter Property="Foreground" Value="{StaticResource MediumRed}"/>
<Setter Property="Margin" Value="3,3,15,31"/>
</Trigger>
</Style.Triggers>
</Style>
<Style x:Key="FTC_DetailError" TargetType="TextBlock">
<Style.Setters>
<Setter Property="FontFamily" Value="Open Sans Condensed"/>
<Setter Property="Control.FontWeight" Value="Light" />
<Setter Property="Foreground" Value="{StaticResource TitleWhite}"/>
<Setter Property="FontSize" Value="15" />
<Setter Property="Margin" Value="0"/>
<Setter Property="Padding" Value="10,3"/>
<Setter Property="HorizontalAlignment" Value="Stretch"/>
<Setter Property="Background" Value="{StaticResource MediumRed}"/>
</Style.Setters>
</Style>
所有的魔法都发生在属性模板中。下列情况必须包含在资源字典的顶部声明:
> xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
> xmlns:cmd="http://www.galasoft.ch/mvvmlight"
所有魔术发生在定义的控件模板的模板属性。你不能在控制模板本身中包装一个i:交互,它必须包含在一个派生的对象中,几乎任何东西,边界,scrollviewer,wrappanel等......然后你设置通风触发器和命令属性。它们应该很容易遵循,我将文本框名称作为命令参数传递。您在屏幕截图中看到的客户端“框”是一个网格,其数据上下文设置为父视图模型的新客户端对象属性。所以为了访问父视图模型中的命令,我必须引用父级的datacontext并调用命令属性。
同样,我意识到这是一个非常具体的场景,但我认为它有一些可以帮助其他人的例子。现在我可以为应用程序中的所有文本框定义一种样式,它们是数据输入,并且我想要触发基本的验证过程。这将使我不必单独在所有文本框上定义自定义命令行为,而这一切都是在xaml中完成的,并且没有代码。
干杯