Question

在为Winows Phone 7.1制作MVC应用程序时，我一直在关注MSDN教程作为参考： http://msdn.microsoft.com/en-us/library/hh286405(v=vs.92).aspx

在我的应用程序中，我在一个表中有一个对象，它实现了实现的INotifyPropertyChanging和INotifyPropertyChanged接口以及如下属性：

private DateTime lastViewDate;
[Column]
public DateTime LastViewDate
{
    get { return lastViewDate; }
    set
    {
       if (lastViewDate != value)
       {
           NotifyPropertyChanging("LastViewDate");
           lastViewDate = value;
           NotifyPropertyChanged("LastViewDate");
       }
    }
}

当LastViewDate属性发生更改时，即使该属性显然存在，也会在调用NotifyPropertyChanging时抛出MissingMethodException。那么我做错了什么？（我在wp7编程中是一个菜鸟，所以它可能很明显，只是对我而言）

编辑：更多信息

这是一个接口方法，带有一些额外的调用来检查方法：

    // Used to notify that a property is about to change
    private void NotifyPropertyChanging(string propertyName)
    {
        var type = this.GetType();
        var method = type.GetMethod(propertyName); // null
        var getMethod = type.GetMethod("get_" + propertyName); // works
        var setMethod = type.GetMethod("set_" + propertyName); // works
        var methods = type.GetMethods(); // set_LastViewDate is in the method list
        //
        if (PropertyChanging != null)
        {
            PropertyChanging(this, new PropertyChangingEventArgs(propertyName));
        }
    }

将调用更改为NotifyPropertyChanging（＆＃34; set_LastViewDate＆＃34;）;仍然给出相同的例外。（并且＆＃39;方法＆＃39;在调试类型检查中变为空）

编辑：

堆栈追踪：

System.MissingMethodException was unhandled
Message=MissingMethodException
StackTrace:
   at System.Activator.InternalCreateInstance(Type type, Boolean nonPublic, StackCrawlMark& stackMark)
   at System.Activator.CreateInstance(Type type)
   at System.Data.Linq.WorkAround.ActivationHelper.CreateInstance(Type type)
   at System.Data.Linq.ChangeTracker.StandardChangeTracker.StandardTrackedObject.CreateDataCopy(Object instance)
   at System.Data.Linq.ChangeTracker.StandardChangeTracker.StandardTrackedObject.StartTracking()
   at System.Data.Linq.ChangeTracker.StandardChangeTracker.OnPropertyChanging(Object sender, PropertyChangingEventArgs args)
   at WindowsPhonePlaces.Photo.NotifyPropertyChanging(String propertyName)
   at WindowsPhonePlaces.Photo.set_LastViewDate(DateTime value)
   at WindowsPhonePlaces.Photo.ResetViewDate()
   at WindowsPhonePlaces.PhotoViewerPage.OnNavigatedTo(NavigationEventArgs e)
   at Microsoft.Phone.Controls.PhoneApplicationPage.InternalOnNavigatedTo(NavigationEventArgs e)
   at System.Windows.Navigation.NavigationService.RaiseNavigated(Object content, Uri uri, NavigationMode mode, Boolean isNavigationInitiator, PhoneApplicationPage existingContentPage, PhoneApplicationPage newContentPage)
   at System.Windows.Navigation.NavigationService.CompleteNavigation(DependencyObject content, NavigationMode mode)
   at System.Windows.Navigation.NavigationService.ContentLoader_BeginLoad_Callback(IAsyncResult result)
   at System.Windows.Navigation.PageResourceContentLoader.BeginLoad_OnUIThread(AsyncCallback userCallback, PageResourceContentLoaderAsyncResult result)
   at System.Windows.Navigation.PageResourceContentLoader.<>c__DisplayClass4.<BeginLoad>b__0(Object args)
   at System.Reflection.RuntimeMethodInfo.InternalInvoke(RuntimeMethodInfo rtmi, Object obj, BindingFlags invokeAttr, Binder binder, Object parameters, CultureInfo culture, Boolean isBinderDefault, Assembly caller, Boolean verifyAccess, StackCrawlMark& stackMark)
   at System.Reflection.RuntimeMethodInfo.InternalInvoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, StackCrawlMark& stackMark)
   at System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters)
   at System.Delegate.DynamicInvokeOne(Object[] args)
   at System.MulticastDelegate.DynamicInvokeImpl(Object[] args)
   at System.Delegate.DynamicInvoke(Object[] args)
   at System.Windows.Threading.DispatcherOperation.Invoke()
   at System.Windows.Threading.Dispatcher.Dispatch(DispatcherPriority priority)
   at System.Windows.Threading.Dispatcher.OnInvoke(Object context)
   at System.Windows.Hosting.CallbackCookie.Invoke(Object[] args)
   at System.Windows.Hosting.DelegateWrapper.InternalInvoke(Object[] args)
   at System.Windows.RuntimeHost.ManagedHost.InvokeDelegate(IntPtr pHandle, Int32 nParamCount, ScriptParam[] pParams, ScriptParam& pResult)

Answer 1

我将解决方案作为一个单独的答案在这里说清楚：

问题在于我将构造函数设为私有，并使用静态方法创建我的数据库对象。这不适用于LINQ - 您需要一个无参数的公共构造函数。

感谢@Metro Smurf和@Rajeev Nair搞清楚。

Answer 2

PropertyChanging是否已公开？如果没有，则应将其设置为公开。

对于Windows Phone 7的本地数据库应用程序中的NotifyPropertyChanged上的MissingMethodException

2 个答案: