0

我创建了一个简单的数据网格来显示一些值，让用户更改它们并在后台程序中读回更改后的值。这是 XAML 设计文件

<Window x:Class="MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Grid>
    <Button x:Name="ButAdd" Content="Add Row" HorizontalAlignment="Left" Height="23" Margin="362,34,0,0" VerticalAlignment="Top" Width="77"/>
    <TextBox x:Name="TeBoResult" HorizontalAlignment="Left" Height="90" Margin="52,220,0,0" TextWrapping="Wrap" Text="Display the Row 0 colmn 1 changed value here:" VerticalAlignment="Top" Width="322" AcceptsReturn="True" IsManipulationEnabled="True"/>
    <Button x:Name="ButRead" Content="Read Row 2" HorizontalAlignment="Left" Height="24" Margin="425,184,0,0" VerticalAlignment="Top" Width="82"/>
    <DataGrid x:Name="DaGr" ItemsSource="{Binding}" HorizontalAlignment="Left" Height="133" Margin="10,75,0,0" VerticalAlignment="Top" Width="174" AutoGenerateColumns="False" IsManipulationEnabled="True" EnableColumnVirtualization="True" >
        <DataGrid.Columns>
            <DataGridTextColumn Header="Text" Binding="{Binding Path=No, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
            <DataGridCheckBoxColumn Header="Check box" Binding="{Binding Path=Sel}"/>
            <DataGridComboBoxColumn Header="Combo box" Binding.XmlNamespaceManager="{Binding Path=Drop}"/>
        </DataGrid.Columns>
    </DataGrid>
    <ComboBox x:Name="CoBo_IN" HorizontalAlignment="Left" Height="20" Margin="344,100,0,0" VerticalAlignment="Top" Width="84" Visibility="Visible">
        <ComboBoxItem Content="Move" HorizontalAlignment="Left" Width="88"/>
        <ComboBoxItem Content="Dock" HorizontalAlignment="Left" Width="88" Selected="ComboBoxItem_Selected"/>
    </ComboBox>
</Grid>

而背景vb.net代码在这里

Imports System.Collections.ObjectModel
Imports System.ComponentModel
Imports System.Runtime.CompilerServices
Imports DataGrid.datset
Imports System.Windows
Class MainWindow
    Public Property coll As New ObservableCollection(Of bind)()
    Private Sub ButAdd_Click(sender As Object, e As RoutedEventArgs) Handles ButAdd.Click
       Dim qw As New bind()
       qw.No = "Change Me"
       qw.Sel = Nothing
       qw.Drop = CoBo_IN
       coll.Add(qw)
       DaGr.ItemsSource = coll
    End Sub

   Private Sub ButRead_Click(sender As Object, e As RoutedEventArgs) Handles ButRead.Click
        Dim val As String
        For Each item As bind In DaGr.Items
            val = item.No
            TeBoResult.Text = TeBoResult.Text & val
        Next
   End Sub

End Class

Public Class datset : Implements INotifyPropertyChanged
   Public Event PropertyChanged As PropertyChangedEventHandler _
   Implements INotifyPropertyChanged.PropertyChanged


   Private Sub NotifyPropertyChanged(<CallerMemberName()> Optional ByVal propertyName As String = Nothing)
       RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
   End Sub

   Public Structure bind
       Public Property No As String
       Public Property Sel As Boolean
       Public Property Drop As ComboBox
   End Structure

End Class

因此，当我单击“添加行”按钮时，具有默认内容的行将添加到 TextColumn 和 CheckBoxColumn 但 ComboBoxColumn 不会显示组合！！（但是当我在此单元格内双击时，组合框出现但它是空的）。这种行为可能是什么原因？

接下来，用户将更改 TextColumn 内的内容，并根据需要在 GUI 中进行更改。

接下来，当用户点击按钮 Read Row 时，TextColumn 的所有内容一个接一个地被读取，并显示在 Result 文本框中。问题是虽然 GUI 在顺序读取时有一个新文本，但val变量仍然只显示以前绑定的值。我认为问题出在 TwoWay 绑定，但它似乎是别的东西。

为什么DataGrid上的读取没有给出更新的值？

4

1 回答 1

0

我对VB不太了解，但我可以看到这里有些东西不好。例如ItemsSource="{Binding}". 在这种情况下，您必须在此处引用要绑定的集合coll。代码应该是这样的：

<Window x:Class="MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525"
x:Name="window">
<Grid>
    <Button x:Name="ButAdd" Content="Add Row" HorizontalAlignment="Left" Height="23" Margin="362,34,0,0" VerticalAlignment="Top" Width="77"/>
    <TextBox x:Name="TeBoResult" HorizontalAlignment="Left" Height="90" Margin="52,220,0,0" TextWrapping="Wrap" Text="Display the Row 0 colmn 1 changed value here:" VerticalAlignment="Top" Width="322" AcceptsReturn="True" IsManipulationEnabled="True"/>
    <Button x:Name="ButRead" Content="Read Row 2" HorizontalAlignment="Left" Height="24" Margin="425,184,0,0" VerticalAlignment="Top" Width="82"/>
    <DataGrid x:Name="DaGr" ItemsSource="{Binding col, ElementName =window}" HorizontalAlignment="Left" Height="133" Margin="10,75,0,0" VerticalAlignment="Top" Width="174" AutoGenerateColumns="False" IsManipulationEnabled="True" EnableColumnVirtualization="True" >
        <DataGrid.Columns>
            <DataGridTextColumn Header="Text" Binding="{Binding Path=No, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
            <DataGridCheckBoxColumn Header="Check box" Binding="{Binding Path=Sel, Mode=TwoWay}"/>
            <DataGridComboBoxColumn Header="Combo box" Binding.XmlNamespaceManager="{Binding Path=Drop, Mode=TwoWay"/>
        </DataGrid.Columns>
    </DataGrid>
    <ComboBox x:Name="CoBo_IN" HorizontalAlignment="Left" Height="20" Margin="344,100,0,0" VerticalAlignment="Top" Width="84" Visibility="Visible">
        <ComboBoxItem Content="Move" HorizontalAlignment="Left" Width="88"/>
        <ComboBoxItem Content="Dock" HorizontalAlignment="Left" Width="88" Selected="ComboBoxItem_Selected"/>
    </ComboBox>
</Grid>

注意项目源绑定和窗口名称，还注意绑定应该是两种方式，也用于更新源。这个新的绑定引用了该col集合。现在，在您身后的代码中，您不应在每次添加项目时重新设置网格信息源。如果集合是一个可观察的集合，那么它会自动添加，现在这些项目应该可以工作了::

Private Sub ButAdd_Click(sender As Object, e As RoutedEventArgs) Handles ButAdd.Click
   Dim qw As New bind()
   qw.No = "Change Me"
   qw.Sel = Nothing
   qw.Drop = CoBo_IN
   coll.Add(qw)
End Sub
于 2013-09-20T13:24:43.890 回答