Silverlight DataGrid與組合框 - 未選擇項目

我在使用Silverlight數據網格內的組合框時遇到問題，它們都綁定到DataContext，而DataContext又使用RIA從數據庫中檢索數據。Silverlight DataGrid與組合框 - 未選擇項目

我遇到的問題是當您在組合框中選擇一個值並單擊單元格而不是顯示新選定值的單元格時，單元格顯示爲空。但是 - 只有當您選擇一個尚未在datagrid的另一個單元格中選擇的值時，纔會發生這種情況！選擇一個獨特的值會導致框顯示空

我的代碼如下：

<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

來源

2011-04-14 Gavin Coates

你知道，我已經坐了這個問題很久了，可以NT尋找解決方案。第二個我在網上發佈......它在我身上閃現。發生這種事時我討厭它。無論如何，解決方案如下。

由於數據庫以及數據對象是用強類型鏈接構建的，因此您可以通過執行Permission.User.Property訪問在任何給定權限組中引用的用戶。您也可以分配給這個Permission.User來設置鏈接。

雖然我曾嘗試使用DataDomainSources執行此操作，但它總是給我一個錯誤，指出該對象已經綁定到另一個DataDomainSources。這是因爲您有一個用於權限的DataDomainSources，另一個用於用戶。

但是，使用DataContext時不存在此限制，因爲用戶和權限都存在於同一個DataContext中。

因此，我重新寫的代碼如下：

<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

來源

2011-04-14 13:48:23

以下是可能的解決方案的一個..

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

來源

2011-04-14 11:07:40

Silverlight DataGrid與組合框 - 未選擇項目

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