使用ItemsSource和ItemTemplate的WPF ListBox [英] WPF ListBox using ItemsSource and ItemTemplate

问题描述

当我在WPF ListBox中同时具有ItemsSource和ItemTemplate时，我对如何解析绑定感到困惑.

I'm confused as to how bindings are resolved when I have both an ItemsSource and an ItemTemplate in a WPF ListBox.

我有一个名为ListOfIndexes的ObservableCollection<int>.对于每个索引，我想在数据库表中查找其记录.我希望在IndexToObjectDescriptionConverter中做到这一点.

I have an ObservableCollection<int> called ListOfIndexes. For each index, I want to look up its record in a database table. I hope to do that in the IndexToObjectDescriptionConverter.

<ListBox ItemsSource="{Binding ListOfIndexes}" 
         ItemTemplate="{Binding Converter={StaticResource IndexToObjectDescriptionConverter}}" />

但是转换器中的断点告诉我，ItemTemplate绑定读取的值是窗口本身的—.即ItemsSource和ItemsTemplate的DataContext是相同的.

But a breakpoint in the converter is telling me that the value being read in by the ItemTemplate binding is of the window itself — i.e., the DataContext of the ItemsSource and ItemsTemplate is the same.

请原谅一些，但这似乎是愚蠢的. ItemTemplate的全部要点是渲染ItemsSource中的每个元素，所以我想我认为ItemTemplate的DataContext是要渲染的单个元素.

Pardon a bit of candidness, but this seems DUMB. The entire point of the ItemTemplate is to render each element within the ItemsSource, so I guess I figured that the DataContext of the ItemTemplate would be the individual element being rendered.

也就是说，我如何告诉ItemTemplate它应该担心由ItemsSource表示的各个元素，而不要使用整个窗口的DataContext?

So, that said, how do I tell the ItemTemplate that it should worry about the individual elements represented by the ItemsSource and not use the entire window's DataContext?

推荐答案

您需要为ItemTemplate使用数据模板.然后将其应用于列表中的每个项目

You need to use a data template for the ItemTemplate. This is then applied to each item in the list

MSDN文档在这里: http://msdn.microsoft.com/zh-CN/library/system.windows.controls.itemscontrol.itemtemplate(v=vs.110).aspx

MSDN docs are here: http://msdn.microsoft.com/en-us/library/system.windows.controls.itemscontrol.itemtemplate(v=vs.110).aspx

她的问题与数据上下文范围有关.当您在ListBox上绑定任何属性时，它将使用ListBox的数据上下文-因此，为什么要将该数据上下文传递给转换器.如果您在ItemTemplate中设置数据模板，它将将该模板应用于列表中的每个项目.我想根据您提供的简单代码，您需要将转换器包含在数据模板中:

The issue her is about data context scope. When you bind any property on the ListBox, it will use the data context of the ListBox - hence why that data context is being passed to the converter. If you set a data template inside the ItemTemplate, it will apply that template to each item in the list. I guess based on the simple code you've provided you would need to have the converter inside the data template:

<ListBox ItemsSource="{Binding ListOfIndexes}">
  <ListBox.ItemTemplate>
    <DataTemplate>
      <ContentControl Content="{Binding Converter={StaticResource IndexToObjectDescriptionConverter}}"/>
    </DataTemplate>
  </ListBox.ItemTemplate>
</ListBox>

在这种情况下，将为每个项目呈现ContentControl，并将该项目作为数据上下文.

In this case, the ContentControl will be rendered for each item, with that item as it's data context.

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