WPF列表框绑定只读取可更新的可观察集合。 [英] WPF list box bound to read only observable collection not updating.

问题描述

大家好，



我有一个查询，我确定我之前遇到过这个问题，谷歌搜索的结果却提出了同样的问题我已经实现了（以某种方式）。



我有一个MVVM应用程序，其中一个V-VM是显示一些文件列表。



viewModel有一个只读的observable集合属性，如下所示：

Hi guys,

I have a query and I'm sure I've had the issue before yet the results from googling are bringing up the same thing which I have already implemented (in a fashion).

I have a MVVM application and one of the V-VM's is to display some file listings.

The viewModel has a read only observable collection property which looks like this:

public ReadOnlyObservableCollection<TemplateFileViewModel> ListOfTemplates
{
     get
     {
         m_FileListing = new ObservableCollection<TemplateFileViewModel>();
         if (!String.IsNullOrWhiteSpace(TemplateDirectoryPath))
         {
              foreach (var s in Directory.GetFiles(TemplateDirectoryPath, "*.MyEXT", 
                          IncludeSubFolders ? SearchOption.AllDirectories : 
                          SearchOption.TopDirectoryOnly))
               {
                    m_FileListing.Add(new TemplateFileViewModel(s));
               }
         }

         return new ReadOnlyObservableCollection<TemplateFileViewModel>(m_FileListing);

    }
}

我还有一个属性TemplateDirectoryPath，如下所示：

I also have a property "TemplateDirectoryPath" which looks like this:

public string TemplateDirectoryPath
{
     get { return m_TemplateDirectoryPath; }
     set
     {
         if (Equals(m_TemplateDirectoryPath, value) || !Directory.Exists(value)) return;
         m_TemplateDirectoryPath = value;
         OnPropertyChanged("TemplateDirectoryPath");
         OnPropertyChanged("ListOfTemplates");
     }
}

想法是当TemplateDirectoryPath更新时，会触发一个列表框来刷新它内容，绑定到视图模型上的ListOfTemplates属性。



我的理解是，如果我使用OnPropertyChanged事件，它应该导致视图执行数据更新。



我的列表框绑定如下：

The idea is that when the TemplateDirectoryPath is updated it triggers a list box to refresh its contents, which is bound to the ListOfTemplates property on the view model.

No my understanding is that if I user the "OnPropertyChanged" event it should result in the view doing a data refresh.

My listbox is bound as follows:

<ListBox Grid.Column="0" ItemsSource="{Binding Path=ListOfTemplates, UpdateSourceTrigger=PropertyChanged}" ItemTemplate="{StaticResource TemplateFileDataTemplate}"/>

为什么这不会触发更新屏幕上？从我所看到的一切看来都是正确的，我错过了一些非常明显的东西吗？





谢谢

Why would this not be triggering an update on the screen? From what I can see it all appears correct, am I missing something really obvious?


Thanks

推荐答案

我找到了我的问题，



我的ViewModel继承自实现INotifyPropertyChanged的基类，但是我必须将我的viewModel声明为例如：

I found my Issue,

My ViewModel was inheriting from a base class that implemented INotifyPropertyChanged, however I had to declare my viewModel as such:

internal class myVM: myBaseVM, INotifyPropertyChanged

并确保正确的引用到位，否则无法触发事件。因为我的基类已经实现了INotifyPropertyChanged的方法/事件，所以我不必复制它们的实现。

and ensure the correct references were in place else it failed to trigger the events. Because my base class already implemented the methods/events for INotifyPropertyChanged, I did not have to duplicate their implementation.

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