在DataTemplate中绑定CollectionViewSource [英] Binding a CollectionViewSource within a DataTemplate

问题描述

ContentTemplate是一个数据模板，它显示一个具有成员 FooList（一个ObservableCollection）的对象。

'ContentTemplate' is a DataTemplate that displays an object which has a member 'FooList' (an ObservableCollection).

<DataTemplate x:Key="ContentTemplate">
    <ListBox ItemsSource="{Binding Path=FOO}">
        ...
    </ListBox>
</DataTemplate>

我需要能够使用CollectionViewSource过滤该FooList。通常这很简单，但是我似乎无法在DataTemplate中使用绑定。我尝试这样做：

I need to be able to filter that FooList using a CollectionViewSource. This is usually been straight forward but I can't seem to get the binding to work within a DataTemplate. I attempted to this:

<DataTemplate x:Key="ContentTemplate">
    <DataTemplate.Resources>
        <CollectionViewSource x:Key="CVS" Source="{Binding Path=FooList}" Filter="FooFilter"/>
    <DataTemplate.Resources>
    <ListBox ItemsSource="{Binding Source={StaticResource CVS}}">

我从中得到的错误是：

System.Windows.Data错误：2：找不到目标元素的管理FrameworkElement或FrameworkContentElement。 BindingExpression：Path = FooList; DataItem = null;目标元素是 CollectionViewSource（HashCode = 52991666）； target属性是 Source（类型 Object）

在我看来，这就像是在CollectionViewSource上查找 FooList而不是绑定对象

Which sounds to me like it's looking for 'FooList' on the CollectionViewSource instead of the object bound to the DataTemplate.

所以...如何让它查看正确的对象？

So... how do I get this to look at the correct object?

推荐答案

据我了解，DataTemplate充当有关将哪些内容插入可视化树的指令，但并未成为可视化树本身的一部分。在遇到与上述问题相同的问题后，我才得出这个假设。我通过将CollectionViewSource附加到元素的资源来解决此问题，该元素将是可视树的一部分，在我的例子中是网格。这是起作用的示例：

As I understand it, the DataTemplate acts as instructions on what to insert into the visual tree but does not become a part of the visual tree itself. I only came to this hypothesis after running into the same problem you've described above. I fixed the issue by attaching the CollectionViewSource to the resources of an element that would be part of the visual tree, in my case a grid. Here is the sample that did work:

<DataTemplate DataType="{x:Type TypedLists:AssetModelListViewModel}">
    <Grid>
        <Grid.Resources>
            <CollectionViewSource x:Key="items"
                                  Source="{Binding}">
                <CollectionViewSource.SortDescriptions>
                    <scm:SortDescription PropertyName="AssetType.AssetCategory.Name" />
                    <scm:SortDescription PropertyName="AssetType.Name" />
                    <scm:SortDescription PropertyName="Manufacturer.Name" />
                </CollectionViewSource.SortDescriptions>
            </CollectionViewSource>
        </Grid.Resources>

        <ListView ItemsSource="{Binding Source={StaticResource items}}">

        </ListView>
    </Grid>
</DataTemplate>

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