如何转换一个ComboBox使用绑定CompositeCollection？

问题描述：

我已经具有绑定物品源的组合框...我已经剥夺我的例子下降到关键件：

I have a ComboBox that has a bound items source... I've stripped my example down to the key pieces:

<UserControl x.Class="My.Application.ClientControl"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"                         
             xmlns:conv="clr-namespace:My.Utilities.Converters"
             Name="ClientControl">

    <UserControl.Resources>
        <ResourceDictionary>
            <CollectionViewSource Key="x:ClientsCollection" />
        </ResourceDictionary>

        <conv:ClientOptions x:Key="ClientOptions" />

    </UserControl.Resources>

    ...

    <ComboBox Name="Options" 
              DataContext="ClientsCollection" 
              ItemsSource="{Binding [ClientNumber], Converter={StaticResource ClientOptions}" />

</UserControl>

这工作，但我现在想添加一个手工物品到我的组合框，将触发所谓的替代功能其他...所以我不必移动使用CompositeCollection ......像这样：

This works, but I now want to add a single manual item to my combobox that will trigger alternate functionality called "Other..." so I'm having to move to using the CompositeCollection... like so:

<ComboBox Name="Options"
          DataContext="ClientsCollection">
    <ComboBox.ItemsSource>
        <CompositeCollection>

            <CollectionContainer Collection="{Binding [ClientNumber], Converter={StaticResource ClientOptions} />
            <ComboBoxItem>Other...</ComboBoxItem>
        </CompositeCollection>
</ComboBox>

尝试，因为我可能，绑定的物品是不会使用CompositeCollection时填充。它只能说明手册ComboBoxItem其他...。如果我删除该项目，列表是空的。如果我附上一个断点到转换器不捉任何东西，这似乎表明绑定甚至没有尝试。

Try as I might, the bound items just won't populate when using the CompositeCollection. It only shows the manual ComboBoxItem "Other...". If I remove that item, the list is empty. If I attach a breakpoint to the converter it doesn't catch anything, which seems to indicate that the binding isn't even attempted.

我显然不理解的东西如何在CompositeCollection绑定功能正在发生的事情。有人可以看到一个错误在我的XAML或解释我缺少的是什么？

I am obviously not understanding something about how the binding function in the CompositeCollection is happening. Can someone see an error in my XAML or explain what I'm missing?

答

在声明中CompositeCollection和ComboBox.Resources与ItemsSource的使用={绑定源= {StaticResource的myCompositeCollection}}。

Declare the CompositeCollection in ComboBox.Resources and use it with ItemsSource="{Binding Source={StaticResource myCompositeCollection}}" .

<UserControl x.Class="My.Application.ClientControl"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"                         
         xmlns:conv="clr-namespace:My.Utilities.Converters"
         Name="ClientControl">

<UserControl.Resources>
    <ResourceDictionary>
        <CollectionViewSource Key="x:ClientsCollection" />
    </ResourceDictionary>

    <conv:ClientOptions x:Key="ClientOptions" />
    <CompositeCollection x:Key="myCompositeCollection">

        <CollectionContainer Collection="{Binding Source={StaticResource ClientsCollection}, Path=[ClientNumber], Converter={StaticResource ClientOptions} />
        <ComboBoxItem>Other...</ComboBoxItem>
    </CompositeCollection>

</UserControl.Resources>

...

<ComboBox Name="Options" 
          DataContext="ClientsCollection" 
          ItemsSource="{Binding Source={StaticResource myCompositeCollection}}" />

如果您在声明元素语法ItemsSource属性里面的CompositeCollection中，为CollectionContainer.Collection绑定没有找到它的DataContext的。

If you declare the CompositeCollection inside the ItemsSource property in element syntax, the Binding for the CollectionContainer.Collection doesn't find its DataContext.

参考资料部分里面，像CompositeCollection Freezables继承其声明元素的DataContext的，就好像它们是元素的逻辑孩子。然而，这是资源属性和属性，如ContentControl.Content或包含控制逻辑的孩子（和其他人也许几个）类似属性的特产。如果你使用元素语法来设置属性的值，一般你将不得不指望像的DataContext属性属性值继承不工作，所以没有明确的来源绑定将无法正常工作，无论是。

Inside the Resources section, Freezables like CompositeCollection inherit the DataContext of their declaring element, as if they were logical children of the element. However, this is a speciality of the Resources property and properties like ContentControl.Content or similar properties which contain the logical children of a control (and maybe a few others). If you use element syntax to set the value of a property, in general you would have to expect that property value inheritance for properties like DataContext doesn't work, and so Bindings without an explicit Source won't work, either.

如何转换一个ComboBox使用绑定CompositeCollection？

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