简单的WPF组合框过滤器 [英] Simple WPF combobox filter

问题描述

我搜寻过Google这个简单的解决方案，但没有运气。我有一个标准的WPF组合框，我只是希望能够过滤根据用户键入的前2个或3个字母组合框具有焦点时显示的列表。我尝试了一些编码，包括一些lamba表达式，但错误System.NotSupportedException不断被抛出在指定combobox.Items.Filter的行。我不使用MVVM，只是喜欢这个简单的功能为用户可用。请帮忙！ P.S。 IsEditable，IsTextSearchEnabled和StaysOpenOnEdit属性设置为true，但是所需的功能尚未实现。

I have searched Google for a simple solution to this but no luck. I have a standard WPF combo box which I would simply like to be able to filter the list displayed according to the first 2 or 3 letters a users types when the combo box has focus. I tried some coding including some lamba expressions but the error "System.NotSupportedException" keeps getting thrown on the line where "combobox.Items.Filter" is specified. I'm not using MVVM and would just like this simple functionality available for the user. Please help! P.S. IsEditable, IsTextSearchEnabled and StaysOpenOnEdit properties are set to true but the desired functionality is not yet achieved.

推荐答案

我开发了一个示例应用程序。我使用字符串作为记录项，你可以使用自己的实体。 Backspace也能正常工作。

I have developed a sample application. I have used string as record item, you can do it using your own entity. Backspace also works properly.

 public class FilterViewModel
    {
        public IEnumerable<string> DataSource { get; set; }       

        public FilterViewModel()
        {
            DataSource = new[] { "india", "usa", "uk", "indonesia" };           
        }
    }

public partial class WinFilter : Window
    {
          public WinFilter()
          {
             InitializeComponent();

             FilterViewModel vm = new FilterViewModel();
             this.DataContext = vm;
          }

          private void Cmb_KeyUp(object sender, KeyEventArgs e)
          {
              CollectionView itemsViewOriginal = (CollectionView)CollectionViewSource.GetDefaultView(Cmb.ItemsSource);

              itemsViewOriginal.Filter = ((o) =>
              {
                  if (String.IsNullOrEmpty(Cmb.Text)) return true;
                  else
                  {
                     if (((string)o).Contains(Cmb.Text)) return true;
                     else return false;
                  }
              });

             itemsViewOriginal.Refresh();

             // if datasource is a DataView, then apply RowFilter as below and replace above logic with below one
             /* 
              DataView view = (DataView) Cmb.ItemsSource; 
              view.RowFilter = ("Name like '*" + Cmb.Text + "*'"); 
             */
          }
     }

XAML

<ComboBox x:Name="Cmb" IsTextSearchEnabled="False" IsEditable="True" ItemsSource="{Binding DataSource}" Width="120"  IsDropDownOpen="True" StaysOpenOnEdit="True" KeyUp="Cmb_KeyUp" />

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