WPF 组合框 SelectedIndex 不起作用
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WPF Combobox SelectedIndex Not Working
提问by coson
I have a WPF user control (FileSelectionView.xaml) with a combo box that displays data. My WPF looks like:
我有一个带有显示数据的组合框的 WPF 用户控件 (FileSelectionView.xaml)。我的 WPF 看起来像：
<ComboBox Width="250"
HorizontalAlignment="Left"
ItemsSource="{Binding Path=FileTypes}"
SelectedItem="{Binding Path=FileType, Mode=TwoWay}" />
In my View Model file (FileSelectionViewModel.cs), I have a List that binds to this control that successfully works. The data looks like:
在我的视图模型文件 (FileSelectionViewModel.cs) 中，我有一个绑定到此控件的列表，该控件成功运行。数据看起来像：
<Please select a file>
File Type 1
File Type 2
I have tried to set the SelectedIndexproperty to 0 so that "<Please select a file>" shows up when the user control renders, but it is not working. It doesn't show anything, but when I click on the combo box, I do see all my items.
我试图将该SelectedIndex属性设置为 0，以便在用户控件呈现时显示“<请选择文件>”，但它不起作用。它没有显示任何内容，但是当我单击组合框时，我确实看到了我的所有项目。
Is there something I'm missing?
有什么我想念的吗？
采纳答案by Jasti
Instead of using SelectedIndex, After updating the ItemsSource, update the selected item with the following code from viewmodel
而不是使用SelectedIndex，更新后，使用ItemsSourceviewmodel中的以下代码更新所选项目
FileType = "Please select a value";
回答by denis morozov
IT works just fine, if you do it in XAML, I don't see it in your XAML, did you forget?
它工作得很好，如果你在 XAML 中这样做，我在你的 XAML 中看不到它，你忘记了吗？
<ComboBox Width="250"
HorizontalAlignment="Left"
ItemsSource="{Binding Path=FileTypes}"
SelectedItem="{Binding Path=FileType, Mode=TwoWay}"
SelectedIndex="0"/>
Note that only will work initially, then you'll have to reset it again when you need it.. via trigger, or code behind.
请注意，这只会在最初有效，然后您必须在需要时再次重置它……通过触发器或隐藏的代码。
