WPF TreeView 数据绑定跟进 [英] WPF TreeView databinding follow up

问题描述

作为我关于SO的第一个TreeView问题的后续，我无法将 TreeView 控件绑定到我的 Commission 对象的 Id 属性及其在同一个 TreeView 控件中的 Products 集合.这是我的简化模型:

As a follow up to my first TreeView question on SO, I'm unable to bind a TreeView control to the Id property of my Commission object and its Products collection in the same TreeView control. Here's my simplified model:

internal class Contract
{
    public string Name { get; set; }
    public ObservableCollection<Commission> Commissions { get; set; }
}

internal class Commission
{
    public string Id { get; set; }
    public ObservableCollection<Product> Products { get; set; }
}

internal class Product
{
   public string Code { get; set; }
}

这是我的问题 XAML.合约返回佣金对象(Commissions)的集合.我已经注释掉了用于返回产品的 HierarchicalDataTemplate.任一 HierarchicalDataTemplate 都可以单独工作，但如果两者都未注释则不行:

Here's my problem XAML. Contract returns a collection of Commission objects (Commissions). I've commented out the HierarchicalDataTemplate for returning Products. Either HierarchicalDataTemplate will work individually, but not if both are uncommented:

<TreeView ItemsSource="{Binding Contract.Commissions}">
                    <TreeView.Resources>
                        <HierarchicalDataTemplate DataType="{x:Type m:Commission}">
                            <TextBlock Text="{Binding Id}" />
                        </HierarchicalDataTemplate> 
                    <!--<HierarchicalDataTemplate DataType="{x:Type m:Commission}" ItemsSource="{Binding Products}">
                            <TextBlock Text="{Binding Code}" />
                        </HierarchicalDataTemplate>-->
                    </TreeView.Resources>
                </TreeView>

如果两个 HierarchicalDataTemplates 都未注释，则会抛出错误，因为我使用了两次唯一的(Commission Type)，但我不知道如何在不使用 Commission Type 作为模板的 DataType 的情况下使 HierarchicalDataTemplate 工作.

If both HierarchicalDataTemplates are uncommented, an error is thrown because I'm using a unique (Commission Type) twice, but I don't know how to make either HierarchicalDataTemplate work without using Commission Type as the template's DataType.

推荐答案

你在这里搞混了.我假设您想显示 Commission 的 Id 以及在每个 Commission 节点下方，子产品的代码值.

You are jumbling up things here. I assume you want to show Commission's Id and beneath each Commission node, child Product's code value.

只需要一个HierarchicalDataTemplate的佣金和一个DataTemplate用于产品:

Only one HierarchicalDataTemplate of Commission is required and one DataTemplate for Product:

<TreeView.Resources>
  <HierarchicalDataTemplate DataType="{x:Type m:Commission}"
                            ItemsSource="{Binding Products}">
      <TextBlock Text="{Binding Id}" />
   </HierarchicalDataTemplate>
   <DataTemplate DataType="{x:Type m:Product}">
      <TextBlock Text="{Binding Code}" />
   </DataTemplate> 
</TreeView.Resources>

说明:

• 为需要包含子节点的节点声明HierarchicalDataTemplate.在您的情况下，佣金.
• 将 ItemsSource 设置为您需要在这些节点下方显示的子集合.在您的情况下 Products.
• 最后，为不包含任何子节点的节点声明DataTemplate.就您而言，产品.

• Declare HierarchicalDataTemplate for nodes which needs to contain child nodes. In your case Commission.
• Set ItemsSource to child collection which you need to shown beneath those nodes. In your case Products.
• Lastly, declare DataTemplate for node which won't contain any child nodes. In your case Product.

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