ComboBox SelectionChanged事件火灾晚

Question

在我的WPF应用程序中，我有一个ComboBox，用于为AutoCompletebox选择ItemFilter。下面是代码：

XAML

<ComboBox 
    Name="SearchFilter" 
    HorizontalAlignment="Right" 
    MinWidth="75" Margin="0,3,0,3" 
    SelectionChanged="SearchFilter_SelectionChanged"> 
      <ComboBoxItem>Full-Time</ComboBoxItem> 
      <ComboBoxItem>Part-Time</ComboBoxItem> 
      <ComboBoxItem>Retired</ComboBoxItem> 
      <ComboBoxItem>Stockholder</ComboBoxItem> 
      <ComboBoxItem>Terminated</ComboBoxItem> 
      <ComboBoxItem>None</ComboBoxItem> 
</ComboBox> 

C＃

private void SearchFilter_SelectionChanged(object sender, SelectionChangedEventArgs e) 
    { 
     if (SearchFilter.SelectedItem != null) 
     { 
      if (SearchFilter.Text == "Full-Time") 
      { 
       EmployeeAutoBox.ItemFilter = PersonFilter_Full; 
      } 
      else if (SearchFilter.Text == "Part-Time") 
      { 
       EmployeeAutoBox.ItemFilter = PersonFilter_Part; 
      } 
      else if (SearchFilter.Text == "Retired") 
      { 
       EmployeeAutoBox.ItemFilter = PersonFilter_Ret; 
      } 
      else if (SearchFilter.Text == "Stockholder") 
      { 
       EmployeeAutoBox.ItemFilter = PersonFilter_Stock; 
      } 
      else if (SearchFilter.Text == "Terminated") 
      { 
       EmployeeAutoBox.ItemFilter = PersonFilter_Term; 
      } 
      else 
      { 
       EmployeeAutoBox.ItemFilter = PersonFilter; 
      } 
     } 
    } 

出于某种原因，经过予改变的所选被改变正在应用的过滤器。例如，我将组合框设置为“全职”，列表筛选器未应用。然后，我将ComboBox设置为“Part-Time，全时间过滤器正在应用，然后我将ComboBox设置为”Retired“，Part Time过滤器正在应用等等等等......我已经使用了ComboBox for类似的东西之前，它通常基于目前在框中的东西，而不是在框中是什么。我在这里缺少什么？

Answer 1

Text只是关于SearchFilter的唯一财产，将不会被更新。您的SelectionChanged处理程序（不要问我为什么不）

SelectedItem会好的，SelectedValue将是很好的（在你的情况下，两者都将被选定ComboBoxItem - 不使用WPF的好方法，但我米不是你的牧师），和SelectedIndex。

我们将对XAML进行一个小改动（见下文），以便我们可以从SelectedValue中获取所选字符串。

private void SearchFilter_SelectionChanged(object sender, SelectionChangedEventArgs e) 
{ 
    // Not sure there's any reason for this null check. 
    if (SearchFilter.SelectedValue != null) 
    { 
     var filter = SearchFilter.SelectedValue as String; 

     switch (filter) 
     { 
      case "Full-Time": 
       EmployeeAutoBox.ItemFilter = PersonFilter_Full; 
       break; 
      case "Part-Time": 
       EmployeeAutoBox.ItemFilter = PersonFilter_Part; 
       break; 
      case "Retired": 
       EmployeeAutoBox.ItemFilter = PersonFilter_Ret; 
       break; 
      case "Stockholder": 
       EmployeeAutoBox.ItemFilter = PersonFilter_Stock; 
       break; 
      case "Terminated": 
       EmployeeAutoBox.ItemFilter = PersonFilter_Term; 
       break; 
      default: 
       EmployeeAutoBox.ItemFilter = PersonFilter; 
       break; 
     } 
    } 
} 

XAML：除了缩进的唯一变化是增加的SelectedValuePath="Content"属性。所做的是，当选择发生变化时（并在事件发生之前），ComboBox现在将查看SelectedItem中的对象，无论它是什么，并查找名为“Content”的属性。如果它发现，它将使用SelectedItem的Content属性的值为SelectedValue。你给这些的内容是字符串：“兼职”等等所以然后

<ComboBox 
    Name="SearchFilter" 
    SelectedValuePath="Content" 
    HorizontalAlignment="Right" 
    MinWidth="75" 
    Margin="0,3,0,3" 
    SelectionChanged="SearchFilter_SelectionChanged" 
    > 
    <ComboBoxItem Tag="Full-Time">Full-Time</ComboBoxItem> 
    <ComboBoxItem>Part-Time</ComboBoxItem> 
    <ComboBoxItem>Retired</ComboBoxItem> 
    <ComboBoxItem>Stockholder</ComboBoxItem> 
    <ComboBoxItem>Terminated</ComboBoxItem> 
    <ComboBoxItem>None</ComboBoxItem> 
</ComboBox>