从ItemsControl的项目绑定到ItemControl的DataContext的 [英] Binding from items in ItemsControl to ItemControl's DataContext

问题描述

我有一个自定义的ItemsTemplateSelector组合框。为控制这些项目的XAML定义，像这样：

I have a ComboBox with a custom ItemsTemplateSelector. The Items for the control are defined in xaml, like so:

<ComboBox ItemTemplateSelector="{StaticResource CommonListSelectorTemplates}" >
    <local:MyItem Heading="First" Text="First Item"/>
    <local:MyItem Heading="Second" Text="Second Item"/>
    <local:MyItemWithValue Heading="Third" Text="Third Item" Value="{Binding TheValue}" />
</ComboBox>

第三项目，我想绑定到组合框的的DataContext TheValue属性的值属性。该绑定失败，出现以下错误：

The third item has a Value property that I wish to bind to the TheValue property on the ComboBox's DataContext. This binding fails with the following error:

找不到理事FrameworkElement的或FrameworkContentElement上的目标元素BindingEx pression：路径= TheValue;的DataItem = NULL;目标元素是'MyItemWithValue（哈希code = 49465727）;目标属性是值 （类型'的Int32'）

"Cannot find governing FrameworkElement or FrameworkContentElement for target element. BindingExpression:Path=TheValue; DataItem=null; target element is 'MyItemWithValue' (HashCode=49465727); target property is 'Value' (type 'Int32')"

我想这是监守项集合不使用组合框的DataContext的。我曾尝试没有成功的RelativeSource不同的排列，所以我的问题是：什么是完成最好的方式结合

I guess it's becuase the Items collection does not use the ComboBox's DataContext. I have tried different permutations of RelativeSource without success, so my question is: What is the best way to accomplish the binding?

编辑：

RV1987回答我的问题，因为它指出。不过，我想是的结合是双向的，也不提出的解决方案，似乎为这方面的工作。麻烦的可能是，我不能在代理是双向绑定;编译器拒绝接受

RV1987 answered my question as it was stated. However, what I want is for the binding to be two-way, and neither of the solutions proposed seem to work for this. The trouble may be that I can't get the binding in the proxy to be two-way; the compiler refuses to accept

的DataContext ={结合，模式=双向}

DataContext="{Binding, Mode=TwoWay}"

推荐答案

ComboboxItems 所以它们没有连接到的数据上下文不可视树的一部分组合框。你必须使用代理绑定提及到DataContext。有关详细的清洁方法，请看看这个链接 -

ComboboxItems are not part of visual tree so they are not connected to the data context of the Combobox. You have to use the proxy binding to refer to the dataContext. For detailed and clean approach please have a look at this link -

<一个href=\"http://tomlev2.word$p$pss.com/2011/03/21/wpf-how-to-bind-to-data-when-the-datacontext-is-not-inherited/\" rel=\"nofollow\">http://tomlev2.word$p$pss.com/2011/03/21/wpf-how-to-bind-to-data-when-the-datacontext-is-not-inherited/

另外，看这个（同样的问题，但在这种情况下，它代替组合框的数据网格）由AngelWPF建议，这也是新的东西，我 -

Also, look at this (same issue but in this case its datagrid in place of combobox) as suggested by AngelWPF, this was also something new to me -

绑定DataGrid列知名度MVVM

编辑 - 此外，你需要设置结合模式双向您comboboxitem而不是静态资源设置它的。这应该工作 -

Edit- Moreover, you need to set binding mode Two way in your comboboxitem instead of setting it in StaticResource. This should work -

<local:MyItemWithValue Heading="Third" Text="Third Item" Value="{Binding TheValue, Mode=TwoWay}" />

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