打开下拉列表后,如何将WPF组合框绑定到其他列表? [英] How do I bind a WPF combo box to a different list when the dropdown is open?
问题描述
我在计划模块中有几个组合框,每个组合框都有一个基于活动"字段的下拉列表.
I have several combo boxes in a Scheduling module that all have dropdown lists based on an "Active" field.
public class Project
{
public int ProjectID { get; set; }
public int ProjectTitle { get; set; }
public bool Active { get; set; }
}
<ComboBox
Name="ProjectComboBox"
ItemsSource="{Binding AllProjects}"
SelectedItem="{Binding Project, Mode=TwoWay}">
</ComboBox>
即使已禁用组合列表中的特定项目,日历的编辑表单也必须始终在其组合框中显示旧信息.但是,如果打开下拉列表,则只能显示列表中仍处于活动状态的那些项目.
The calendar's editing form must always display legacy information in its combo boxes, even if a particular item in a combo list has been deactivated. But if the drop-down is opened, it must only show those items in the list that are still active.
我该怎么做?
我已经在后面的代码中尝试过了
I have tried this, in the codebehind:
private void ProjectComboBox_DropDownOpened(object sender, EventArgs e)
{
ProjectComboBox.SetBinding(ItemsControl.ItemsSourceProperty, "ActiveProjects");
}
private void ProjectComboBox_DropDownClosed(object sender, EventArgs e)
{
ProjectComboBox.SetBinding(ItemsControl.ItemsSourceProperty, "AllProjects");
}
在下拉菜单中显示正确的列表,但取消选择最初选择的项目.如果用户未选择新项目,则在下拉列表关闭时,组合框需要保留其原始选择.
Which displays the correct list in the dropdown, but de-selects the originally-selected Project. If the user does not select a new project, the combo box needs to retain its original selection when the dropdown is closed.
推荐答案
而不是更改ItemsSource,而是通过可见性绑定隐藏不活动的元素:
instead of changing ItemsSource, hide inactive elements via Visibility binding:
<BooleanToVisibilityConverter x:Key="boolToVisibility"/>
<ComboBox Name="ProjectComboBox"
ItemsSource="{Binding AllProjects}"
DisplayMemberPath="ProjectTitle"
SelectedItem="{Binding Project, Mode=TwoWay}">
<ComboBox.ItemContainerStyle>
<Style TargetType="ComboBoxItem">
<Setter Property="Visibility"
Value="{Binding Active, Converter={StaticResource boolToVisibility}}"/>
</Style>
</ComboBox.ItemContainerStyle>
</ComboBox>
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