wpf 修改其 ItemsSource ObservableCollection 后如何刷新组合框
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原文地址: http://stackoverflow.com/questions/7914549/
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How can I refresh a combobox after modifying its ItemsSource ObservableCollection
提问by Грозный
The problems is simple: when ItemsSourceis updated Combobox doesn't "refresh" e.g. new items don't appear to be added to the list of items in the combobox.
问题很简单：何时ItemsSource更新组合框不会“刷新”，例如新项目似乎没有添加到组合框中的项目列表中。
I've tried the solution from aceepted answer to this question: WPF - Auto refresh combobox contentwith no luck.
我已经尝试过这个问题的回答中的解决方案：WPF -没有运气自动刷新组合框内容。
here's my code, XAML:
这是我的代码，XAML：
<ComboBox Name="LeadTypeComboBox" ItemsSource="{Binding LeadTypeCollection}" />
ViewModel:
视图模型：
public ObservableCollection<XmlNode> LeadTypeCollection { get; set; }
the way I update this collection is in the separate method, which loads data from updated XML file: this.LeadTypeCollection = GetLeadTypesDataSource();
我更新这个集合的方式是在单独的方法中，它从更新的 XML 文件加载数据： this.LeadTypeCollection = GetLeadTypesDataSource();
I've also tried using Addfor testing purposes:
我也试过Add用于测试目的：
this.LeadTypeCollection = GetLeadTypesDataSource();
ItemToAdd = LeadTypeCollection[LeadTypeCollection.Count - 1];
this.LeadTypeCollection.Add(ItemToAdd);
the code updating collection definitely kicks off, I can see new items in this collection when debugging, but I don't see them in the combobox.
代码更新集合肯定会启动，调试时我可以在此集合中看到新项目，但在组合框中看不到它们。
Doing this in the xaml code-behind works: LeadTypeComboBox.ItemsSource = MyViewModel.GetLeadTypesDataSource();but I'd like to achieve this with MVVM, i.e. the code must be in ViewModel which isn't aware of LeadTypeComboBox control.
在 xaml 代码隐藏工作中执行此操作：LeadTypeComboBox.ItemsSource = MyViewModel.GetLeadTypesDataSource();但我想使用 MVVM 实现此目的，即代码必须位于不知道 LeadTypeComboBox 控件的 ViewModel 中。
采纳答案by Firedragon
I think I have seen this before and the solution was to update the collection property to raise the change.
我想我以前见过这个，解决方案是更新集合属性以引发更改。
i.e.
IE
public class MyViewModel : INotifyPropertyChanged
{
private ObservableCollection<XmlNode> leadTypeCollection;
public string LeadTypeCollection
{
get { return leadTypeCollection; }
set
{
if (value != leadTypeCollection)
{
leadTypeCollection = value;
NotifyPropertyChanged("LeadTypeCollection");
}
}
public MyViewModel()
{
leadTypeCollection = new ObservableCollection<XmlNode>();
}
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(String info)
{
PropertyChanged.Raise(this, info);
}
}
I have an extension method for raising the property (as found elsewhere on stackoverflow):
我有一个提高属性的扩展方法（如在 stackoverflow 上的其他地方找到的）：
public static void Raise(this PropertyChangedEventHandler handler, object sender, string propertyName)
{
if (null != handler)
{
handler(sender, new PropertyChangedEventArgs(propertyName));
}
}
回答by blindmeis
Firedragons answer would work, but i would prefer to initialize the LeadTypeCollection just once and use clear, add remove to update your collection.
Firedragons 的答案会起作用，但我更愿意只初始化 LeadTypeCollection 一次并使用 clear, add remove 来更新您的收藏。
var update = GetLeadTypesDataSource();
this.LeadTypeCollection.Clear();
foreach(var item in update)
{
this.LeadTypeCollection.Add(item);
}
your xaml binding should work if the datacontext is right
如果数据上下文正确，您的 xaml 绑定应该可以工作
<ComboBox Name="LeadTypeComboBox" ItemsSource="{Binding LeadTypeCollection}" />
回答by vinsa
A simple method is to change ItemsSource with empty list and then change it back to your updated source. A snippet from my project which is working:
一个简单的方法是使用空列表更改 ItemsSource，然后将其更改回更新后的源。我的项目中的一个片段正在运行：
RulesTable.ItemsSource = Rules.rulesEmpty;
RulesTable.ItemsSource = Rules.Get();
