ComboBox- SelectionChanged 事件具有旧值，而不是新值 [英] ComboBox- SelectionChanged event has old value, not new value

问题描述

C#、.NET 4.0、VS2010.

C#, .NET 4.0, VS2010.

WPF 新手.我的 MainWindow 上有一个 ComboBox.我钩住了所述组合框的 SelectionChanged 事件.但是，如果我检查事件处理程序中组合框的值，它具有旧值.这听起来更像是SelectionChanging"事件，而不是 SelectionChanged 事件.

New to WPF. I have a ComboBox on my MainWindow. I hooked the SelectionChanged event of said combo box. However, if I examine the value of the combo box in the event handler, it has the old value. This sounds more like a "SelectionChanging" event, than a SelectionChanged event.

如何在选择实际发生后获取 ComboBox 的新值?

How do I get the new value of the ComboBox after the selection has actually happend?

目前:

this.MyComboBox.SelectionChanged += new SelectionChangedEventHandler(OnMyComboBoxChanged);

...
private void OnMyComboBoxChanged(object sender, SelectionChangedEventArgs e)
{
    string text = this.MyComboBox.Text;
}

注意，如果我使用在事件参数中传递的对象，我会得到相同的行为，例如e.OriginalSource.

Note, I get the same behaviour if I use the object being passed in the event args, e.g. e.OriginalSource.

推荐答案

根据 MSDN，e.AddedItems:

According to MSDN, e.AddedItems:

获取包含所选项目的列表.

Gets a list that contains the items that were selected.

所以你可以使用:

private void OnMyComboBoxChanged(object sender, SelectionChangedEventArgs e)
{
    string text = (e.AddedItems[0] as ComboBoxItem).Content as string;
}

如果您对来自 sender 的 Items 使用 string 值，您也可以使用 SelectedItem:

You could also use SelectedItem if you use string values for the Items from the sender:

private void OnMyComboBoxChanged(object sender, SelectionChangedEventArgs e)
{
    string text = (sender as ComboBox).SelectedItem as string;
}

或

private void OnMyComboBoxChanged(object sender, SelectionChangedEventArgs e)
{
    string text = ((sender as ComboBox).SelectedItem as ComboBoxItem).Content as string;
}

由于 Content 和 SelectedItem 都是对象，更安全的方法是使用 .ToString() 而不是 作为字符串

Since both Content and SelectedItem are objects, a safer approach would be to use .ToString() instead of as string

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