组合框与空项目？ [英] ComboBox with empty item?

问题描述

假设我们有一个DataSource绑定到数据库的集合。当然没有null项目。如何向组合框中添加无效项，以便首次加载用户将看到一个空字符串。我不想在集合中添加一个dummy / void对象。 在XAML中最佳化。任何提案？

Suppose we have a DataSource bind to a collection from Database. There is no null item of course. How to add a void item into a ComboBox, so that at first load user would see an empty string. I don't want to add a dummy/void object into the Collection. Optimally in XAML. Any proposals?

推荐答案

<ComboBox Name="myComboBox" Width="200" Background="White">    
    <ComboBox.ItemsSource>    
        <CompositeCollection>
           <ComboBoxItem IsEnabled="False" Foreground="Black">Select Item</ComboBoxItem>
           <CollectionContainer Collection="{Binding Source={StaticResource DataKey}}" />    
        </CompositeCollection>
    </ComboBox.ItemsSource>
</ComboBox>

EDIT

由于评论中提及了 @surfen ， BindingProxy 是绑定问题的解决方法

As @surfen mentioned in comment, BindingProxy is workaround for the binding issue

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