使用Path =。和转换器内部绑定 [英] Using Path=. and Converter inside Binding

问题描述

我无法为TreeViewItem定义触发器。我相信这只是一些语法问题，但我不知道还有什么要写的...

I have trouble defining a trigger for TreeViewItems. I believe it is just some syntax problem, but I don't know what else to write...

这是触发器：

<DataTrigger Binding="{Binding Path=., Converter=IsNodeConverter}" Value="True">
    <Setter Property="Focusable" Value="False"/>
</DataTrigger>

由于它在 TreeView.ItemContainerStyle ， DataContext 应该是包含的项目本身。 Item可以是类型 Node 或 Entry ，我想触发所有类型为$的项目c $ c> Node 。所以我写了一个转换器：

Since it is defined inside TreeView.ItemContainerStyle, the DataContext should be the contained item itself. The Item can either be of type Node or Entry and I want to trigger for all Items that are of type Node. So I wrote a converter:

public class IsNodeConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is Node)
            return true;

        return false;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

哪些返回 true 如果它得到一个 Node 作为输入， false 否则。

Which returns true if it gets a Node as input and false otherwise.

但是在部分 Binding ={Binding Path =。，Converter = IsNodeConverter}编译器抱怨：IValueConverter无法从字符串转换。 （原文：Vom TypeConverter-ObjektfürIValueConverter wird das Konvertieren aus einer Zeichenfolge nichtunterstützt）我不明白这一点：DataContext是一个类型为 Entry 的对象或 Node 和 Binding Path =。应该保持这样。那么问题是什么呢？编译器讲什么字符串？如何纠正这一点，以便编译器不会抱怨？

But in the part Binding="{Binding Path=., Converter=IsNodeConverter}" the compiler complains: "IValueConverter cannot convert from string." (original: "Vom TypeConverter-Objekt für IValueConverter wird das Konvertieren aus einer Zeichenfolge nicht unterstützt.") I don't understand this at all: DataContext is an object of type Entry or Node, and Binding Path=. should keep it that way. So what is the problem? What string is the compiler talking about? How do I correct this so that the compiler does not complain?

以下是TreeView的完整代码以供参考。集合'AllNodesAndEntries'是一个 ObservableCollection< object> ，其中包含 Node 和条目 s。

Here is the full code of the TreeView for reference. The collection ´AllNodesAndEntries´ is an ObservableCollection<object> that contains both Nodes and Entrys.

<TreeView ItemsSource="{Binding AllNodesAndEntries}">
    <TreeView.Resources>
        <HierarchicalDataTemplate ItemsSource="{Binding Children}" DataType="{x:Type usrLibVM:Node}">
            <TextBlock Text="{Binding Name}" Background="LightBlue"/>
        </HierarchicalDataTemplate>
        <DataTemplate DataType="{x:Type usrLibVM:Entry}">
            <TextBlock Text="{Binding Name}" Background="LightSalmon"/>
        </DataTemplate>
    </TreeView.Resources>
    <TreeView.ItemContainerStyle>
        <Style TargetType="{x:Type TreeViewItem}">
            <Style.Triggers>
                <DataTrigger Binding="{Binding Path=., Converter=IsNodeConverter}" Value="True">
                    <Setter Property="Focusable" Value="False"/>
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </TreeView.ItemContainerStyle>
</TreeView>

推荐答案

您的转换器肯定在ResourceDictionary中声明，所以它应该被引用为StaticResource：

Your converter is certainly declared in a ResourceDictionary, so it should be referenced as StaticResource:

Binding="{Binding Path=., Converter={StaticResource IsNodeConverter}}" 

或更短：

Binding="{Binding Converter={StaticResource IsNodeConverter}}" 

这篇关于使用Path =。和转换器内部绑定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！