WPF TreeView控件绑定到的ObservableCollection没有更新根节点 [英] WPF TreeView bound to ObservableCollection not updating root nodes

问题描述

对不起 - 我的问题是几乎相同的这一个但因为它没有得到一个可行的答案，我希望其他人有一些新的想法。

Sorry - my question is almost identical to this one but since it didn't receive a viable answer, I am hoping that someone else has some fresh ideas.

我有一个绑定到一个单一类型的层次结构中的WPF的TreeView：

I have a WPF TreeView that is bound to a hierarchy of a single type:

public class Entity
{
    public string Title { get; set; }
    public ObservableCollection<Entity> Children { get; set; }
}

实体类实现INotifyPropertyChanged，但我已经省略此code为清晰。

The Entity class implements INotifyPropertyChanged, but I have omitted this code for clarity.

该TreeView控件绑定到一个ObservableCollection＆LT;实体>每个实体实例，通过它的儿童财产公开了一组包含的实体实例：

The TreeView is bound to an ObservableCollection<Entity> and each Entity instance exposes a set of contained Entity instances via its Children property:

<TreeView ItemsSource="{Binding Path=Entities}">
    <TreeView.Resources>
        <HierarchicalDataTemplate DataType="{x:Type local:Entity}" ItemsSource="{Binding Path=Children}">
           <TextBlock Text="{Binding Path=Title}" />
        </HierarchicalDataTemplate>
   </TreeView.Resources>
</TreeView>

最初的TreeView结合预期和正确显示的多层次结构。此外，当孩子们的收藏品之一的成员以编程方式修改，更改正确反映在TreeView。

Initially the TreeView binds as expected and correctly displays a multi-level hierarchy. Also, when the membership of one of the Children collections is programmatically modified, the changes are correctly reflected in the TreeView.

但是，更改到根成员级别的ObservableCollection＆LT的成员;实体>不会反映在TreeView

However, changes to the membership of the root member level ObservableCollection<Entity> are not reflected in the TreeView.

任何建议将是AP preciated。

Any suggestions would be appreciated.

谢谢，
蒂姆·

Thanks, Tim

推荐答案

我最初的猜测是，你有类似的根节点以下内容：

My initial guess is that you have something like the following for the root node:

public ObservableCollection<Entity> Entities
{
    get;
    set;
}

然后，而不是做一些[好]这样的：

Then, instead of doing something [good] like the following:

Entities.Clear();
foreach (var item in someSetOfItems)
    Entities.Add(item);

您正在做的事情[衰]是这样的：

You are doing something [bad] like this:

Entities = new ObservableCollection<Entity>(someSetOfItems);

您应该能够通过使实体属性的支持字段追查问题只读：

You should be able to track down the issue by making the backing field of the Entities property readonly:

private readonly ObservableCollection<Entity> _entities
    = new ObservableCollection<Entity>();

public ObservableCollection<Entity> Entities
{
    get
    {
        return _entities;
    }
}

这篇关于WPF TreeView控件绑定到的ObservableCollection没有更新根节点的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！