Silverlight DataGrid CellEditTemplate组合框数据绑定问题。 [英] Silverlight DataGrid CellEditTemplate combobox databinding issue.

问题描述

我正在使用Entity Framework后端的RIA服务在ASPX上开发SilverLight应用程序。我有很好的加载DataGrid包括相关的表数据。我现在正在使用组合框更改来更新字段。在我调试时，我可以看到实体对象的更改，但它不会持久存在。我尝试在RowEditEnding事件中调用DataGrid上的CommitEdit，它只是让应用程序崩溃而导致错误。



绑定CB：

I am working on a SilverLight app on ASPX with RIA services from Entity Framework backend. I have the loading of the DataGrid just fine including the related table data. I am now working on updating the fields with the combobox changes. As I debug I can see the changes on the entity object, but it does not persist. I tried calling CommitEdit on the DataGrid in the RowEditEnding event which just crashes the app with giving me the error.

Bind the CB's:

Private Sub dgStaff_PreparingCellForEdit(sender As Object, e As System.Windows.Controls.DataGridPreparingCellForEditEventArgs) Handles dgStaff.PreparingCellForEdit
   columnIndex = e.Column.DisplayIndex
   Dim cb As ComboBox = TryCast(e.EditingElement, ComboBox)
   If cb IsNot Nothing Then
     cb.DisplayMemberPath = "Description"
     Select Case columnIndex
       Case 2
         cb.SelectedItem = curPerson.Station.StationId
         cb.ItemsSource = stations
         cb.SelectedValue = curPerson.Station.StationId
       Case 3
         cb.SelectedItem = curPerson.Shift.ShiftId
         cb.ItemsSource = shifts
         cb.SelectedValue = curPerson.Shift.ShiftId
       Case 4
         cb.SelectedItem = curPerson.Team.TeamId
         cb.ItemsSource = teams
         cb.SelectedValue = curPerson.Team.TeamId
     End Select
   End If
End Sub

获取当前实体对象：

Get the current entity object:

Private Sub dgStaff_BeginningEdit(sender As Object, e As System.Windows.Controls.DataGridBeginningEditEventArgs) Handles dgStaff.BeginningEdit
    curPerson = CType(e.Row.DataContext, BMServiceRef.Personnel)
End Sub

获取新值并将其应用于实体对象：

Get the new values and apply them to the entity object:

Private Sub cb_SelectionChanged(sender As System.Object, e As System.Windows.Controls.SelectionChangedEventArgs)
  Dim cb As ComboBox = DirectCast(sender, ComboBox)
  Select Case columnIndex
    Case 2
      curPerson.StationId = CType(cb.SelectedItem, BMServiceRef.Station).StationId
    Case 3
      curPerson.ShiftId = CType(cb.SelectedItem, BMServiceRef.Shift).ShiftId
    Case 4
      curPerson.TeamId = CType(cb.SelectedItem, BMServiceRef.Team).TeamId
  End Select
End Sub

如果我可以添加更多信息，请告诉我。谢谢你看...

Let me know if I can add any more info. Thanks for looking...

推荐答案

我有一个解决方法。在combobox selectionChanged事件中，我将选择保存到服务器。在cellEditEnd事件中，我再次更新dataGrid。我仍然希望得到组合框中显示的当前值 - selectedIndex。如果有人可以帮助那部分（或其他部分），我会给你解决方案。

这两个绑定不起作用，这就是我必须重新绑定dataGrid的原因。

I have a workaround. In the combobox selectionChanged event I save selection to server. In the cellEditEnd event I update the dataGrid again. I would still like to get the current value to show in the combobox - the selectedIndex. If someone can help with that part(or the rest) I'll give you the solution.
The twoWay binding does not work and this is why I have to rebind the dataGrid.

<DataTemplate>
  <ComboBox ItemsSource="{Binding Path=stations,Mode=TwoWay}" SelectionChanged="cb_SelectionChanged" DropDownClosed="dd_closed" />
</DataTemplate>

你需要绑定SelectedValue

< combobox height =23>

DisplayMemberPath =name

SelectedValuePath =id

SelectedValue ={Binding Path = buildingId，Mode = TwoWay}

ItemsSource ={Binding Buildings}

宽度=160>

You need to bind the SelectedValue
<combobox height="23">
DisplayMemberPath="name"
SelectedValuePath="id"
SelectedValue="{Binding Path=buildingId, Mode=TwoWay}"
ItemsSource="{Binding Buildings}"
Width="160">

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