如何在 LINQ to Entities 中使用 WPF TreeView HierarchicalDataTemplate? [英] How do I use a WPF TreeView HierarchicalDataTemplate with LINQ to Entities?
问题描述
我的 .edmx ADO.NET 实体数据模型文件中有一个 Page 类,具有父级和子级属性.它用于页面的层次结构.
I've got a Page class in my .edmx ADO.NET Entity Data Model file with with Parent and Children properties. It's for a hierarchy of Pages.
删除了失效的 ImageShack 链接 - ADO.NET Entity Framework Hierarchical Page Class
这是在我的 SQL 数据库中处理的,Page 表中的 ParentId 外键绑定到同一个 Page 表的 Id 主键.
This is handled in my SQL database with a ParentId foreign key in the Page table bound to the Id primary key of that same Page table.
如何在 WPF TreeView 中显示此层次结构?
How do I display this hierarchy in a WPF TreeView?
推荐答案
我在 Abe Heidebrecht 的帮助下完成了这项工作一>.非常感谢他.
I got this working with help from Abe Heidebrecht. Much thanks to him.
这是我的 XAML...
Here's my XAML...
<Window x:Class="Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:PageManager"
Title="Window1" Height="300" Width="300" Name="Window1">
<Grid>
<TreeView Margin="12" Name="TreeViewPages" ItemsSource="{Binding}" TreeViewItem.Expanded="TreeViewPages_Expanded">
<TreeView.Resources>
<HierarchicalDataTemplate DataType="{x:Type local:Page}" ItemsSource="{Binding Children}">
<TextBlock Text="{Binding Path=ShortTitle}" />
</HierarchicalDataTemplate>
</TreeView.Resources>
</TreeView>
</Grid>
</Window>
这是我的 Visual Basic 代码...
Here's my Visual Basic code...
Class Window1
Private Sub Window1_Loaded(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles MyBase.Loaded
Dim db As New PageEntities
Dim RootPage = From p In db.Page.Include("Children") _
Where (p.Parent Is Nothing) _
Select p
TreeViewPages.ItemsSource = RootPage
End Sub
Private Sub TreeViewPages_Expanded(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
Dim ExpandedTreeViewItem As TreeViewItem = DirectCast(e.OriginalSource, TreeViewItem)
Dim PageId As Guid = DirectCast(ExpandedTreeViewItem.DataContext, Page).Id
Dim db As New PageEntities
Dim ChildPages = From p In db.Page.Include("Children") _
Where p.Parent.Id = PageId _
Select p
ExpandedTreeViewItem.ItemsSource = ChildPages
End Sub
End Class
当窗口加载时,从数据库中查询根节点及其子节点并插入到树中.
When the window loads, the root node and its children are queried from the database and inserted into the tree.
每次扩展节点时,都会从数据库中查询该节点的子节点和孙节点并将其插入到树中.
Each time a node is expanded, that node's children and grandchildren are queried from the database and inserted into the tree.
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