Question

我最近从WinForms转移到了WPF，看起来像datagrids处理在这里更复杂。我必须在应用程序运行时从用户界面手动在数据网格中添加数据。

我有以下XAML代码：

 <DataGrid x:Name="dataGridAdd" HorizontalAlignment="Left" Margin="591,360,0,0" VerticalAlignment="Top" Height="118" Width="202" AutoGenerateColumns="False" ScrollViewer.CanContentScroll="False" VerticalScrollBarVisibility="Disabled" Grid.Column="1" CanUserDeleteRows="True">
        <DataGrid.Columns>
            <DataGridTextColumn Binding="{Binding Varenr}" ClipboardContentBinding="{x:Null}" Header="Vare nr.:" Width="100"/>
            <DataGridTextColumn Binding="{Binding Antal}" ClipboardContentBinding="{x:Null}" Header="Antal" Width="100"/>
        </DataGrid.Columns>
    </DataGrid>

后台代码：

public partial class Window1 : Window
{

    ObservableCollection<Add> list;
    public Window1()
    {
        InitializeComponent();

        list = new ObservableCollection<Add>();
        dataGridAdd.ItemsSource = list;     
    }

    public class Add
    {
        public string Varenr { get; set; }

        public string Antal { get; set; }
    }

    private void buttonPrint_Click(object sender, RoutedEventArgs e)
    {
        Add addval = dataGridAdd.SelectedItem as Add;

        while (dataGridAdd.Items.Count > 1)
           {
             string vare = addval.Varenr;
             string antal1 = addval.Antal;                                          
             list.Remove(addval);            
           }
    }
}

关键是，当我使用单行添加数据并按下打印按钮时，它会按预期删除项目：

enter image description here

当我添加多行时会出现问题：

enter image description here

while循环变为无限，因为在这种情况下dataGridAdd.Items.Count不会低于值“2”。我该如何处理这个问题？

Answer 1

这是一个错误的逻辑。例如，如果您在dataGridAdd中有超过2个项目，那么您的代码将被执行如下：

    Add addval = dataGridAdd.SelectedItem as Add;

    while (dataGridAdd.Items.Count > 1)
       {
         string vare = addval.Varenr;
         string antal1 = addval.Antal;                                          
         list.Remove(addval);            
       }

将addval = dataGridAdd.SelectedItem添加为Add;
while（dataGridAdd.Items.Count＆gt; 3）// dataGridAdd.Items.Count = 3，list.Count = 3
string vare = addval.Varenr; string antal1 = addval.Antal;
list.Remove（addval）; //返回true，删除成功，list.count = 2
while（dataGridAdd.Items.Count＆gt; 2）// false，dataGridAdd.Items.Count = 2
string vare = addval.Varenr; string antal1 = addval.Antal;
list.Remove（addval）; //返回false，删除失败，list.count = 2 ....

所以，dataGridAdd.Items.Count不会低于值“2”

<强>更新

运行此代码，您将在list.Remove（addval）之后看到dataGridAdd.SelectedIndex = -1和dataGridAdd.SelectedItem = null;所以，如果再次移除，它将返回flase。

private void Button_Click(object sender, RoutedEventArgs e)
        {
                Add addval = dataGridAdd.SelectedItem as Add;


                Console.WriteLine(dataGridAdd.SelectedIndex);
                Console.WriteLine(dataGridAdd.SelectedItem);
                string vare = addval.Varenr;
                string antal1 = addval.Antal;
                list.Remove(addval);
                Console.WriteLine(dataGridAdd.SelectedIndex);
                Console.WriteLine(dataGridAdd.SelectedItem);

        }

Answer 2

使用wpf / mvvm时，不要删除或添加数据网格中的项目！您删除并添加项目到基础数据源。

  public ObservableCollection<MyDataTypeObjects> MyData {get;set;}

  public MyDataTypeObjects MySelectedData {get;set;}

XAML

  <DataGrid ItemsSource="{Binding MyData}" SelectedItem="{Binding MySelectedData}"/>

Answer 3

现在可以使用以下代码：

private void buttonPrint_Click(object sender, RoutedEventArgs e)
    {
        for (int i = 0; i < dataGridAdd.Items.Count - 1; i++)
        {                                      
           Add addval = dataGridAdd.Items[i] as Add;
           string vare = addval.Varenr;
           string antal1 = addval.Antal;
        }
        list.Clear();
    }

删除数据网格中的行

3 个答案: