WPF Combobox IsDropDownOpen属性使用WriteOnly属性绑定OneWayToSource模式

时间：2014-10-09 20:52:09

标签： c# wpf mvvm binding combobox

在一个简单的WPF MVVM应用程序中，我得到了如下视图：

<Grid DataContext="{StaticResource PageViewModel}">
    <StackPanel>
       <ComboBox Width="100" Margin="10"
                 IsDropDownOpen="{Binding ComboOpen, Mode=OneWayToSource}"
                 IsEditable="True">
           <ComboBoxItem>1</ComboBoxItem>
           <ComboBoxItem>2</ComboBoxItem>
           <ComboBoxItem>3</ComboBoxItem>
           <ComboBoxItem>4</ComboBoxItem>
           <ComboBoxItem>5</ComboBoxItem>
       </ComboBox> 
    </StackPanel>  
</Grid>

和View Model就像：

public bool ComboOpen
{
    set 
    { 
        System.Diagnostics.Debug.Print(" Combobox is " + (value?" dropped down":" closed"));         
    }
}

我在构建应用程序的Windows 7上获得了正确的行为。一旦我运行应用程序，我就可以看到组合框是可丢弃的，用户可以删除组合框并选择值。我也可以输入Combobox来选择一个值。

之后，我拿了应用程序并在Windows Xp SP3上运行它并发出爆炸声。我再也无法放下组合框了。我能够输入值，然后选择正确的项目。

有人可以告诉你为什么组合框没有在Windows XP Sp3中掉线吗？

提前致谢...

[更新日期：2014年10月13日]仅提供更多信息：我试图在家用机器上重现这个问题，而且我在Windows 7上也感到惊讶，我无法降低下拉框。我从我的工作机器复制了调试日志，它完美地工作并从家用机器上复制：

从家庭计算机中调试日志：

'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\assembly\GAC_MSIL\Microsoft.VisualStudio.HostingProcess.Utilities\10.0.0.0__b03f5f7f11d50a3a\Microsoft.VisualStudio.HostingProcess.Utilities.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Windows.Forms\v4.0_4.0.0.0__b77a5c561934e089\System.Windows.Forms.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Drawing\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Drawing.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System\v4.0_4.0.0.0__b77a5c561934e089\System.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\assembly\GAC_MSIL\Microsoft.VisualStudio.HostingProcess.Utilities.Sync\10.0.0.0__b03f5f7f11d50a3a\Microsoft.VisualStudio.HostingProcess.Utilities.Sync.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\assembly\GAC_MSIL\Microsoft.VisualStudio.Debugger.Runtime\10.0.0.0__b03f5f7f11d50a3a\Microsoft.VisualStudio.Debugger.Runtime.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Users\XXXXXX\Desktop\X\DropdownIssue\bin\Debug\DropdownIssue.vshost.exe', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\System.Data\v4.0_4.0.0.0__b77a5c561934e089\System.Data.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Core\v4.0_4.0.0.0__b77a5c561934e089\System.Core.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Xml\v4.0_4.0.0.0__b77a5c561934e089\System.Xml.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\Microsoft.CSharp\v4.0_4.0.0.0__b03f5f7f11d50a3a\Microsoft.CSharp.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Xml.Linq\v4.0_4.0.0.0__b77a5c561934e089\System.Xml.Linq.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Data.DataSetExtensions\v4.0_4.0.0.0__b77a5c561934e089\System.Data.DataSetExtensions.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Xaml\v4.0_4.0.0.0__b77a5c561934e089\System.Xaml.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\WindowsBase\v4.0_4.0.0.0__31bf3856ad364e35\WindowsBase.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\PresentationCore\v4.0_4.0.0.0__31bf3856ad364e35\PresentationCore.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\PresentationFramework\v4.0_4.0.0.0__31bf3856ad364e35\PresentationFramework.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
The thread 'vshost.NotifyLoad' (0x2150) has exited with code 0 (0x0).
The thread '<No Name>' (0x2088) has exited with code 0 (0x0).
The thread '<No Name>' (0x20f4) has exited with code 0 (0x0).
The thread 'vshost.LoadReference' (0x1604) has exited with code 0 (0x0).
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Users\XXXXXXXXXX\Desktop\X\DropdownIssue\bin\Debug\DropdownIssue.exe', Symbols loaded.
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Configuration\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Configuration.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Step into: Stepping over non-user code 'DropdownIssue.App.App'
Step into: Stepping over non-user code 'DropdownIssue.App.InitializeComponent'
Combobox is  closed
System.Windows.Data Error: 17 : Cannot get 'ComboOpen' value (type 'Boolean') from '' (type 'PageViewModel'). BindingExpression:Path=ComboOpen; DataItem='PageViewModel' (HashCode=52085517); target element is 'ComboBox' (Name=''); target property is 'IsDropDownOpen' (type 'Boolean') ArgumentException:'System.ArgumentException: Property Get method was not found.
   at System.Reflection.RuntimePropertyInfo.GetValue(Object obj, BindingFlags invokeAttr, Binder binder, Object[] index, CultureInfo culture)
   at System.Reflection.RuntimePropertyInfo.GetValue(Object obj, Object[] index)
   at MS.Internal.Data.PropertyPathWorker.GetValue(Object item, Int32 level)
   at MS.Internal.Data.PropertyPathWorker.RawValue(Int32 k)'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\PresentationFramework.Aero\v4.0_4.0.0.0__31bf3856ad364e35\PresentationFramework.Aero.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.

从正常工作的机器调试日志。

'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\assembly\GAC_MSIL\Microsoft.VisualStudio.HostingProcess.Utilities\10.0.0.0__b03f5f7f11d50a3a\Microsoft.VisualStudio.HostingProcess.Utilities.dll'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Windows.Forms\v4.0_4.0.0.0__b77a5c561934e089\System.Windows.Forms.dll'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Drawing\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Drawing.dll'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System\v4.0_4.0.0.0__b77a5c561934e089\System.dll'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\assembly\GAC_MSIL\Microsoft.VisualStudio.HostingProcess.Utilities.Sync\10.0.0.0__b03f5f7f11d50a3a\Microsoft.VisualStudio.HostingProcess.Utilities.Sync.dll'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\assembly\GAC_MSIL\Microsoft.VisualStudio.Debugger.Runtime\10.0.0.0__b03f5f7f11d50a3a\Microsoft.VisualStudio.Debugger.Runtime.dll'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'D:\Temp\DropdownIssue\DropdownIssue\bin\Debug\DropdownIssue.vshost.exe'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\System.Data\v4.0_4.0.0.0__b77a5c561934e089\System.Data.dll'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Core\v4.0_4.0.0.0__b77a5c561934e089\System.Core.dll'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Xml\v4.0_4.0.0.0__b77a5c561934e089\System.Xml.dll'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\Microsoft.CSharp\v4.0_4.0.0.0__b03f5f7f11d50a3a\Microsoft.CSharp.dll'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Xml.Linq\v4.0_4.0.0.0__b77a5c561934e089\System.Xml.Linq.dll'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Data.DataSetExtensions\v4.0_4.0.0.0__b77a5c561934e089\System.Data.DataSetExtensions.dll'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Xaml\v4.0_4.0.0.0__b77a5c561934e089\System.Xaml.dll'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\WindowsBase\v4.0_4.0.0.0__31bf3856ad364e35\WindowsBase.dll'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_32\PresentationCore\v4.0_4.0.0.0__31bf3856ad364e35\PresentationCore.dll'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\PresentationFramework\v4.0_4.0.0.0__31bf3856ad364e35\PresentationFramework.dll'
The thread 'vshost.NotifyLoad' (0x4680) has exited with code 0 (0x0).
The thread 'vshost.LoadReference' (0x3b70) has exited with code 0 (0x0).
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'D:\Temp\DropdownIssue\DropdownIssue\bin\Debug\DropdownIssue.exe', Symbols loaded.
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Configuration\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Configuration.dll'
Step into: Stepping over method without symbols 'DropdownIssue.App.App'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\PresentationFramework-SystemData\v4.0_4.0.0.0__b77a5c561934e089\PresentationFramework-SystemData.dll'
 Combobox is  closed
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\PresentationFramework.Aero\v4.0_4.0.0.0__31bf3856ad364e35\PresentationFramework.Aero.dll'
'DropdownIssue.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\UIAutomationTypes\v4.0_4.0.0.0__31bf3856ad364e35\UIAutomationTypes.dll'
The thread '<No Name>' (0xf60) has exited with code 0 (0x0).

1 个答案:

答案 0 :(得分：0)

必须打开MS支持的票证才能解决此问题。他们建议如下：

  1. 基于OneWayToSource设计，不需要getter。
  2. xaml解析器在.Net 4.0中进行了重新设计，这对它来说是一个遗留问题。 .Net 4.5+解决了这个问题。

    3. 我已经在.NET 4.5中验证过了，问题就解决了。

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