WPF 组合框选择更改未正确反映到数据网格答案

【问题标题】：WPF Combobox selection changed not reflected correctly to datagridWPF 组合框选择更改未正确反映到数据网格
【发布时间】：2021-09-18 11:38:18
【问题描述】：

我有一个包含不同版本下拉列表的组合框。当我单击组合框中的一个值时，它应该显示此特定版本的响应数据。但是当我运行代码时，对 Combobox 值的第一次单击（比如说 2019 年）没有做任何事情。如果我单击另一个（2020），它会显示与 2019 相关的数据。DataGrid 似乎总是比 Combobox 选择晚单击。

这是我的代码：

public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            dropdownList.Items.Add("<all>");
            dropdownList.SelectedIndex = 0;
            grid_Construct();
        }
        private void grid_Construct()
        {
            dataGrid1.Items.Clear();

            .......

            foreach (string file in files)
            {
                .........

                if (version == dropdownList.Text || dropdownList.Text == "<all>")
                {
                    dataGrid1.Items.Add(new pluginItem { addinversion = version, filepath = file });
                }
                if (!dropdownList.Items.Contains(version))
                {
                    dropdownList.Items.Add(version);
                }
            }
        }

        private void ComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            grid_Construct();
        }

        public class pluginItem
        {
            public string addinversion { get; set; }
            public string filepath { get; set; }
        }
    }

XAML：

<Grid Grid.ColumnSpan="2" Height="34" VerticalAlignment="Top" Background="#FF9C9B9B">
            <Button x:Name="btnAbout" Content="About" Margin="0,6,24,7" Click="BnAbout_Click" RenderTransformOrigin="1.229,0.459" HorizontalAlignment="Right" Width="58"/>
            <Label Content="Revit Version : " HorizontalAlignment="Left" Height="27" Margin="12,2,0,0" VerticalAlignment="Top" Width="140"/>
            <ComboBox x:Name="dropdownList" HorizontalAlignment="Left" Height="21" Margin="101,6,0,0" 
                      VerticalAlignment="Top" Width="178" SelectionChanged="ComboBox_SelectionChanged" SelectedIndex="0"
                      ItemsSource="{Binding Path=pluginItem}"/>
        </Grid>
        <DataGrid x:Name="dataGrid1" Grid.ColumnSpan="2" Margin="15,54,15,51" Background="White" 
                  HeadersVisibility="Column" MinColumnWidth="5" RowHeight="22" CanUserReorderColumns="False" 
                  AreRowDetailsFrozen="True" RowDetailsVisibilityMode="Visible" CanUserAddRows="False" 
                  SelectionChanged="dataGrid1_SelectionChanged" ItemsSource="{Binding Path=pluginItem}" VirtualizingStackPanel.IsVirtualizing="False">

            <DataGrid.Columns>
                <DataGridTextColumn Header="Version" Width="118*" Binding="{Binding addinversion}" IsReadOnly="True"/>
                <DataGridTextColumn Header="Addin Path" Width="440*" Binding="{Binding filepath}" IsReadOnly="True"/>
            </DataGrid.Columns>

【问题讨论】：

标签： c# wpf combobox datagrid

【解决方案1】：

这是因为您在ComboBox_SelectionChanged(..) 中调用了grid_Construct();，此时尚未应用更改（至少ComboBox.Text），所以ComboBox.Text 返回旧值。

更正

if (version == (dropdownList.SelectedValue as string) || (dropdownList.SelectedValue as string) == "<all>")

【讨论】：

【解决方案2】：

您应该将version 与ComboBox 的SelectedItem 属性进行比较，而不是Text 属性：

private void grid_Construct()
{
    dataGrid1.Items.Clear();

    //.......

    string selectedItem = dropdownList.SelectedItem as string;
    foreach (string file in files)
    {
        //.........

        if (version == selectedItem || selectedItem == "<all>")
        {
            dataGrid1.Items.Add(new pluginItem { addinversion = version, filepath = file });
        }
        if (!dropdownList.Items.Contains(version))
        {
            dropdownList.Items.Add(version);
        }
    }
}

【讨论】：