[英]Entity Framework & Binding synchronisation
Imagine I have an entity: 假设我有一个实体:
public class MyObject
{
public string Name { get; set; }
}
And I have a ListBox: 我有一个ListBox:
<ListBox x:Name="lbParts">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Name}"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
I bind it to a collection in code-behind: 我将其绑定到代码隐藏的集合中:
ObjectQuery<MyObject> componentQuery = context.MyObjectSet;
Binding b = new Binding();
b.Source = componentQuery;
lbParts.SetBinding(ListBox.ItemsSourceProperty, b);
And the on a button click I add an entity to the MyObjectSet: 然后在按钮上单击“我将实体添加到MyObjectSet”:
var myObject = new MyObject { Name = "Test" };
context.AddToMyObjectSet(myObject);
Here is the problem - this object needs to update in the UI to. 这里是问题-该对象需要在UI中更新到。 But it is not added there :( 但它没有添加到那里:(
The ObjectQuery<T>
class doesn't implement the INotifyCollectionChanged
interface, so it doesn't notify the UI when an item is added or removed. ObjectQuery<T>
类未实现INotifyCollectionChanged
接口,因此在添加或删除项目时不会通知UI。 You need to use an ObservableCollection<T>
which is a copy of your ObjectQuery<T>
; 您需要使用ObservableCollection<T>
,它是ObjectQuery<T>
的副本; when you add an item to the ObjectQuery<T>
, also add it to the ObservableCollection<T>
. 将项目添加到ObjectQuery<T>
,还应将其添加到ObservableCollection<T>
。
Binding : 捆绑 :
private ObservableCollection<MyObject> _myObjects;
...
_myObjects = new ObservableCollection(context.MyObjectSet);
Binding b = new Binding();
b.Source = _myObjects;
lbParts.SetBinding(ListBox.ItemsSourceProperty, b);
Add item : 添加项目 :
var myObject = new MyObject { Name = "Test" };
context.AddToMyObjectSet(myObject);
_myObjects.Add(myObject);
The BookLibrary sample application is using an EntityObservableCollection. BookLibrary示例应用程序正在使用EntityObservableCollection。 This way you get always both worlds updated: WPF and Entity Framework. 这样,您将始终获得更新:WPF和实体框架。
You can download the sample application here: WPF Application Framework (WAF) . 您可以在此处下载示例应用程序: WPF应用程序框架(WAF) 。
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