Silverlight DataGrid与组合框 - 未选择项目

我在使用Silverlight数据网格内的组合框时遇到问题，它们都绑定到DataContext，而DataContext又使用RIA从数据库中检索数据。Silverlight DataGrid与组合框 - 未选择项目

我遇到的问题是当您在组合框中选择一个值并单击单元格而不是显示新选定值的单元格时，单元格显示为空。但是 - 只有当您选择一个尚未在datagrid的另一个单元格中选择的值时，才会发生这种情况！选择一个独特的值会导致框显示空

我的代码如下：

<navigation:Page x:Class="Chemical_Management_System.EditPermissions" 
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
     mc:Ignorable="d" 
     xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation" 

     d:DesignWidth="640" d:DesignHeight="480" 
     Title="EditPermissions Page" Width="640" HorizontalAlignment="Center" 
      xmlns:riaControls="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.DomainServices" 
      xmlns:my="clr-namespace:Chemical_Management_System.Web" 
      xmlns:myn="clr-namespace:Chemical_Management_System" 
      xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk"> 



<Grid x:Name="LayoutRoot"> 
    <Border BorderBrush="Silver" BorderThickness="1" Height="45" HorizontalAlignment="Left" Margin="10,10,0,0" Name="Border1" Style="{StaticResource HeaderBackground}" VerticalAlignment="Top" Width="618"> 
     <TextBlock Height="23" Name="TextBlock21" Style="{StaticResource HeaderText}" Text="Edit Permissions" /> 
    </Border> 
    <riaControls:DomainDataSource AutoLoad="True" d:DesignData="{d:DesignInstance my:Permissions, CreateList=true}" Height="0" Name="PermissionsDomainDataSource" QueryName="GetPermissionsQuery" SubmittedChanges="OnSubmitChanges" Width="0"> 
     <riaControls:DomainDataSource.DomainContext> 
      <my:DataContext /> 
     </riaControls:DomainDataSource.DomainContext> 
    </riaControls:DomainDataSource> 

    <riaControls:DomainDataSource AutoLoad="True" d:DesignData="{d:DesignInstance my:PermissionLookups, CreateList=true}" Height="0" Name="PermissionLookupsDomainDataSource" QueryName="GetPermissionLookupsQuery" Width="0"> 
     <riaControls:DomainDataSource.DomainContext> 
      <my:DataContext /> 
     </riaControls:DomainDataSource.DomainContext> 
    </riaControls:DomainDataSource> 

    <riaControls:DomainDataSource AutoLoad="True" d:DesignData="{d:DesignInstance my:Users, CreateList=true}" Height="0" Name="UsersDomainDataSource" QueryName="GetUsersQuery" Width="0"> 
     <riaControls:DomainDataSource.DomainContext> 
      <my:DataContext /> 
     </riaControls:DomainDataSource.DomainContext> 
    </riaControls:DomainDataSource> 

    <Button Content="Apply" Height="23" HorizontalAlignment="Left" Margin="553,445,0,0" Name="btnApply" VerticalAlignment="Top" Width="75" /> 
    <sdk:DataGrid AutoGenerateColumns="False" Height="378" HorizontalAlignment="Left" ItemsSource="{Binding ElementName=PermissionsDomainDataSource, Path=Data}" Margin="12,61,0,0" Name="PermissionsDataGrid" RowDetailsVisibilityMode="VisibleWhenSelected" VerticalAlignment="Top" Width="615"> 
     <sdk:DataGrid.Columns> 

      <sdk:DataGridTemplateColumn Header="User" MinWidth="190"> 
       <sdk:DataGridTemplateColumn.CellTemplate> 
        <DataTemplate> 
         <TextBlock Text="{Binding User.Name}" Padding="5,0,0,0" /> 
        </DataTemplate> 
       </sdk:DataGridTemplateColumn.CellTemplate> 
       <sdk:DataGridTemplateColumn.CellEditingTemplate> 
        <DataTemplate> 
         <ComboBox ItemsSource="{Binding UsersDomainDataSource}" 

            Loaded="ComboBoxUsers_Loaded" 
            SelectionChanged="UsersComboBox_SelectionChanged" 
           > 
          <ComboBox.ItemTemplate> 
           <DataTemplate> 
            <TextBlock Text="{Binding Name}" /> 
           </DataTemplate> 
          </ComboBox.ItemTemplate> 

         </ComboBox> 

        </DataTemplate> 
       </sdk:DataGridTemplateColumn.CellEditingTemplate> 
      </sdk:DataGridTemplateColumn> 
      <sdk:DataGridTemplateColumn Header="Permission" MinWidth="175"> 
       <sdk:DataGridTemplateColumn.CellTemplate> 
        <DataTemplate> 
         <TextBlock Text="{Binding PermissionLookup.Description}" /> 
        </DataTemplate> 
       </sdk:DataGridTemplateColumn.CellTemplate> 
       <sdk:DataGridTemplateColumn.CellEditingTemplate> 
        <DataTemplate> 
         <ComboBox ItemsSource="{Binding PermissionLookupsDomainDataSource}" 

            Loaded="ComboBox_Loaded" 
            SelectionChanged="PermissionLookupComboBox_SelectionChanged" 
           > 
          <ComboBox.ItemTemplate> 
           <DataTemplate> 
            <TextBlock Text="{Binding Description}" /> 
           </DataTemplate> 
          </ComboBox.ItemTemplate> 

         </ComboBox> 

        </DataTemplate> 
       </sdk:DataGridTemplateColumn.CellEditingTemplate> 
      </sdk:DataGridTemplateColumn> 
      <sdk:DataGridTextColumn x:Name="DescriptionColumn" Binding="{Binding Path=Description}" Header="Description" MinWidth="245" /> 

     </sdk:DataGrid.Columns> 
    </sdk:DataGrid> 
    <Button Content="New" Height="23" HorizontalAlignment="Left" Margin="12,445,0,0" Name="btnNew" VerticalAlignment="Top" Width="75" /> 
    <Button Content="Delete" Height="23" HorizontalAlignment="Left" Margin="93,445,0,0" Name="btnDelete" VerticalAlignment="Top" Width="75" /> 
    <Button Content="Cancel" Height="23" HorizontalAlignment="Left" Margin="472,445,0,0" Name="btnCancel" VerticalAlignment="Top" Width="75" /> 
</Grid>

Partial Public Class EditPermissions 
Inherits Page 

Dim Context As New Web.DataContext() 
Dim user As New CurrentUser() 

Public Sub New() 
    InitializeComponent() 

    AddHandler user.userLoadedCompleted, AddressOf userLoaded 
End Sub 

'Executes when the user navigates to this page. 
Protected Overrides Sub OnNavigatedTo(ByVal e As System.Windows.Navigation.NavigationEventArgs) 

End Sub 

Private Sub userLoaded() 
    If user.permissionCheck("Admin") = False Then 
     MessageBox.Show("You do not have permission to access this page") 
     NavigationService.Navigate(New Uri("/Home", UriKind.Relative)) 
    End If 
End Sub 

Private Sub PermissionsDomainDataSource_LoadedData(ByVal sender As System.Object, ByVal e As System.Windows.Controls.LoadedDataEventArgs) Handles PermissionsDomainDataSource.LoadedData 

    If e.HasError Then 
     System.Windows.MessageBox.Show(e.Error.ToString, "Load Error", System.Windows.MessageBoxButton.OK) 
     e.MarkErrorAsHandled() 
    End If 
End Sub 


Private Sub PermissionLookupsDomainDataSource_LoadedData(ByVal sender As System.Object, ByVal e As System.Windows.Controls.LoadedDataEventArgs) Handles PermissionLookupsDomainDataSource.LoadedData 

    If e.HasError Then 
     System.Windows.MessageBox.Show(e.Error.ToString, "Load Error", System.Windows.MessageBoxButton.OK) 
     e.MarkErrorAsHandled() 
    End If 
End Sub 

Private Sub ComboBox_Loaded(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) 
    ' set combobox items source from wherever you want 
    Dim combo As ComboBox = sender 
    combo.ItemsSource = Me.PermissionLookupsDomainDataSource.DataView 
End Sub 

Private Sub ComboBoxUsers_Loaded(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) 
    ' set combobox items source from wherever you want 
    Dim combo As ComboBox = sender 
    combo.ItemsSource = Me.UsersDomainDataSource.DataView 
End Sub 

Private Sub btnApply_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles btnApply.Click 
    Me.PermissionsDomainDataSource.SubmitChanges() 
    NavigationService.Navigate(New Uri("/AdminHome", UriKind.Relative)) 
End Sub 

Private Sub btnDelete_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles btnDelete.Click 
    If PermissionsDataGrid.SelectedItem IsNot Nothing Then 
     Dim selected As Web.Permissions = PermissionsDataGrid.SelectedItem 
     Me.PermissionsDomainDataSource.DataView.Remove(selected) 
    Else 
     MessageBox.Show("Please select a permission entry to delete") 
    End If 

End Sub 

Private Sub btnNew_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles btnNew.Click 
    Dim permission As New Web.Permissions 
    Me.PermissionsDomainDataSource.DataView.Add(permission) 
End Sub 

Private Sub btnCancel_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles btnCancel.Click 
    Me.PermissionsDomainDataSource.RejectChanges() 
    NavigationService.Navigate(New Uri("/AdminHome", UriKind.Relative)) 
End Sub 

Private Sub OnSubmitChanges(ByVal sender As Object, ByVal e As SubmittedChangesEventArgs) 
    If (e.HasError) Then 
     MessageBox.Show("Error: " + e.Error.ToString) 
    End If 

End Sub 

Private Sub UsersComboBox_SelectionChanged(ByVal sender As System.Object, ByVal e As System.Windows.Controls.SelectionChangedEventArgs) 

    Dim permission As Web.Permissions = PermissionsDataGrid.SelectedItem 
    Dim selected As ComboBox = sender 
    Dim user As Web.Users = selected.SelectedItem 

    permission.UserID = user.ID 
    selected.UpdateLayout() 
End Sub 

Private Sub PermissionLookupComboBox_SelectionChanged(ByVal sender As System.Object, ByVal e As System.Windows.Controls.SelectionChangedEventArgs) 

    Dim permission As Web.Permissions = PermissionsDataGrid.SelectedItem 
    Dim selected As ComboBox = sender 
    Dim permissionLookup As Web.PermissionLookups = selected.SelectedItem 

    permission.PermissionID = permissionLookup.ID 

End Sub 
End Class

来源

2011-04-14 Gavin Coates

你知道，我已经坐了这个问题很久了，可以NT寻找解决方案。第二个我在网上发布......它在我身上闪现。发生这种事时我讨厌它。无论如何，解决方案如下。

由于数据库以及数据对象是用强类型链接构建的，因此您可以通过执行Permission.User.Property访问在任何给定权限组中引用的用户。您也可以分配给这个Permission.User来设置链接。

虽然我曾尝试使用DataDomainSources执行此操作，但它总是给我一个错误，指出该对象已经绑定到另一个DataDomainSources。这是因为您有一个用于权限的DataDomainSources，另一个用于用户。

但是，使用DataContext时不存在此限制，因为用户和权限都存在于同一个DataContext中。

因此，我重新写的代码如下：

<navigation:Page x:Class="Chemical_Management_System.EditPermissions" 
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
     mc:Ignorable="d" 
     xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation" 

     d:DesignWidth="640" d:DesignHeight="480" 
     Title="EditPermissions Page" Width="640" HorizontalAlignment="Center" 
      xmlns:riaControls="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.DomainServices" 
      xmlns:my="clr-namespace:Chemical_Management_System.Web" 
      xmlns:myn="clr-namespace:Chemical_Management_System" 
      xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk"> 



<Grid x:Name="LayoutRoot" > 
    <Border BorderBrush="Silver" BorderThickness="1" Height="45" HorizontalAlignment="Left" Margin="10,10,0,0" Name="Border1" Style="{StaticResource HeaderBackground}" VerticalAlignment="Top" Width="618"> 
     <TextBlock Height="23" Name="TextBlock21" Style="{StaticResource HeaderText}" Text="Edit Permissions" /> 
    </Border> 


    <Button Content="Apply" Height="23" HorizontalAlignment="Left" Margin="553,445,0,0" Name="btnApply" VerticalAlignment="Top" Width="75" /> 
    <Button Content="New" Height="23" HorizontalAlignment="Left" Margin="12,445,0,0" Name="btnNew" VerticalAlignment="Top" Width="75" /> 
    <Button Content="Delete" Height="23" HorizontalAlignment="Left" Margin="93,445,0,0" Name="btnDelete" VerticalAlignment="Top" Width="75" /> 
    <Button Content="Cancel" Height="23" HorizontalAlignment="Left" Margin="472,445,0,0" Name="btnCancel" VerticalAlignment="Top" Width="75" /> 
    <sdk:DataGrid AutoGenerateColumns="False" Height="364" HorizontalAlignment="Left" Margin="10,75,0,0" Name="dataGrid" VerticalAlignment="Top" Width="618" DataContext="dataContext.Permissions"> 
     <sdk:DataGrid.Columns> 
      <sdk:DataGridTextColumn x:Name="DescriptionColumn" Binding="{Binding Path=Description}" Header="Description" MinWidth="245" /> 

      <sdk:DataGridTemplateColumn Header="User" MinWidth="190"> 
       <sdk:DataGridTemplateColumn.CellTemplate> 
        <DataTemplate> 
         <TextBlock Text="{Binding User.Name}" Padding="5,0,0,0" /> 
        </DataTemplate> 
       </sdk:DataGridTemplateColumn.CellTemplate> 

       <sdk:DataGridTemplateColumn.CellEditingTemplate> 
        <DataTemplate> 
         <ComboBox Loaded="UserComboBox_Loaded" SelectionChanged="UserComboBox_SelectionChanged"> 
          <ComboBox.ItemTemplate> 
           <DataTemplate> 
            <TextBlock Text="{Binding Name}" /> 
           </DataTemplate> 
          </ComboBox.ItemTemplate> 
         </ComboBox> 
        </DataTemplate> 
       </sdk:DataGridTemplateColumn.CellEditingTemplate> 


      </sdk:DataGridTemplateColumn> 

      <sdk:DataGridTemplateColumn Header="Permission" MinWidth="190"> 
       <sdk:DataGridTemplateColumn.CellTemplate> 
        <DataTemplate> 
         <TextBlock Text="{Binding PermissionLookup.Description}" Padding="5,0,0,0" /> 
        </DataTemplate> 
       </sdk:DataGridTemplateColumn.CellTemplate> 

       <sdk:DataGridTemplateColumn.CellEditingTemplate> 
        <DataTemplate> 
         <ComboBox Loaded="PermissionComboBox_Loaded" SelectionChanged="PermissionComboBox_SelectionChanged"> 
          <ComboBox.ItemTemplate> 
           <DataTemplate> 
            <TextBlock Text="{Binding Description}" /> 
           </DataTemplate> 
          </ComboBox.ItemTemplate> 
         </ComboBox> 
        </DataTemplate> 
       </sdk:DataGridTemplateColumn.CellEditingTemplate> 


      </sdk:DataGridTemplateColumn> 


     </sdk:DataGrid.Columns> 
    </sdk:DataGrid> 
</Grid>

Partial Public Class EditPermissions 
Inherits Page 

Dim Context As New Web.DataContext() 
Dim user As New CurrentUser() 


Public Sub New() 
    InitializeComponent() 

    AddHandler user.userLoadedCompleted, AddressOf userLoaded 

    Context.Load(Context.GetPermissionsQuery()) 
    Context.Load(Context.GetUsersQuery()) 
    Context.Load(Context.GetPermissionLookupsQuery) 


    dataGrid.ItemsSource = Context.Permissions 


End Sub 

'Executes when the user navigates to this page. 
Protected Overrides Sub OnNavigatedTo(ByVal e As System.Windows.Navigation.NavigationEventArgs) 

End Sub 

Private Sub userLoaded() 
    If user.permissionCheck("Admin") = False Then 
     MessageBox.Show("You do not have permission to access this page") 
     NavigationService.Navigate(New Uri("/Home", UriKind.Relative)) 
    End If 
End Sub 





Private Sub UserComboBox_Loaded(sender As System.Object, e As System.Windows.RoutedEventArgs) 
    Dim combo As ComboBox = sender 
    combo.ItemsSource = Context.Users 
End Sub 

Private Sub UserComboBox_SelectionChanged(sender As System.Object, e As System.Windows.Controls.SelectionChangedEventArgs) 
    Dim combo As ComboBox = sender 
    Dim user As Web.Users = combo.SelectedItem 

    Dim currentPermission As Web.Permissions = dataGrid.SelectedItem 
    currentPermission.User = user 

End Sub 


Private Sub PermissionComboBox_Loaded(sender As System.Object, e As System.Windows.RoutedEventArgs) 
    Dim combo As ComboBox = sender 
    combo.ItemsSource = Context.PermissionLookups 
End Sub 

Private Sub PermissionComboBox_SelectionChanged(sender As System.Object, e As System.Windows.Controls.SelectionChangedEventArgs) 
    Dim combo As ComboBox = sender 
    Dim permissionLookup As Web.PermissionLookups = combo.SelectedItem 

    Dim currentPermission As Web.Permissions = dataGrid.SelectedItem 
    currentPermission.PermissionLookup = permissionLookup 

End Sub 

Private Sub btnApply_Click(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles btnApply.Click 
    Context.SubmitChanges() 
End Sub 

Private Sub btnNew_Click(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles btnNew.Click 
    Dim newpermission As New Web.Permissions 
    Context.Permissions.Add(newpermission) 
End Sub 


End Class

来源

2011-04-14 13:48:23

以下是可能的解决方案的一个..

http://richardgavel.wordpress.com/2009/04/17/silverlight-combobox-and-asynchronous-population-of-underlying-data/

来源

2011-04-14 11:07:40

Silverlight DataGrid与组合框 - 未选择项目

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