2

尝试更新绑定到数据集的 listView 时，我遇到了一些奇怪的问题。

数据集从 SQL 获取信息，需要每 5 分钟自动更新一次。目前我正在使用 backgroudWorker 获取新信息并将其插入数据集中。

然后在 RunWorkerCompleted 事件上我这样做

listView1.DataContex = dataSet.Tables["table"].DefaultView

DoWork 事件包含类似这样的内容

dataSet.Clear();

SqlDataAdapter adapter = new SqlDataAdapter(
                "SELECT [ContainerID] ,[UserID], [Spur], [Wave] ,[Date] FROM [ScannedItems] " + 
                "WHERE [Message] LIKE '%Success%'" + 
                "UNION ALL " +
                "SELECT [ContainerID] ,[UserID], [Spur], [Wave] ,[Date] FROM [Workstation].[dbo].[AllSpurs] " +
                "WHERE [Message] LIKE '%" + "Success" + "' ORDER BY [Date] DESC", connection);


            DataTableMapping mapping = adapter.TableMappings.Add("Table", "Packages Scanned");
            mapping.ColumnMappings.Add("ContainerID", "Cont");
            mapping.ColumnMappings.Add("UserID", "User");
            mapping.ColumnMappings.Add("Spur", "Spur");
            mapping.ColumnMappings.Add("Wave", "Wave");
            mapping.ColumnMappings.Add("Date", "Date");

            connection.Open();

            adapter.FillSchema(dataSet, SchemaType.Mapped);
            adapter.Fill(dataSet);

            connection.Close();

这在我调用 worker.RunWorkerAsync(); 时有效 在启动时。

但是，当计时器调用它时，表会变为空白（所有数据都已删除）。如果我尝试在 listVIew 中滚动，我会收到错误消息

Object reference not set to the instance of an object

但是，如果我单击其中一列的标题，则新数据将变得可见并且可以滚动。

谁能让我知道我做错了什么。

这是 listView 的 XAML

<ListView ItemContainerStyle="{StaticResource cnListView}" ItemsSource="{Binding Path=Table}" Margin="7,5,31,7" Name="listView2" SelectionMode="Multiple" util:GridViewSort.AutoSort="True" LostFocus="LostFocus">
                    <ListView.View>
                        <GridView x:Name="gridView1" AllowsColumnReorder="False" ColumnHeaderTemplate="{StaticResource cnDataViewHeader}">
                            <GridViewColumn DisplayMemberBinding="{Binding Path=Cont}" util:GridViewSort.PropertyName="Cont" Header="ContainerID" Width="350" />
                            <GridViewColumn DisplayMemberBinding="{Binding Path=User}" util:GridViewSort.PropertyName="User" Header="User" Width="200" />
                            <GridViewColumn DisplayMemberBinding="{Binding Path=Spur}" util:GridViewSort.PropertyName="Spur" Header="Spur" Width="120" />
                            <GridViewColumn DisplayMemberBinding="{Binding Path=Wave, StringFormat='dd-MM-yyyy HH:mm:ss'}" util:GridViewSort.PropertyName="Wave" Header="Wave" Width="250" />
                            <GridViewColumn DisplayMemberBinding="{Binding Path=Date, StringFormat='dd-MM-yyyy HH:mm:ss'}" util:GridViewSort.PropertyName="Date" Header="Time Scanned" Width="250" />
                        </GridView>
                    </ListView.View>
                </ListView>

太感谢了

较小的项目完整代码：

XAML

<Window x:Class="backWorkerTest.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="502" Width="989">
<Grid>
    <ListView ItemsSource="{Binding MeetCollection}" Height="340" HorizontalAlignment="Left" Margin="12,12,0,0" Name="listView1" VerticalAlignment="Top" Width="914">
        <ListView.View>
            <GridView>
                    <GridViewColumn Header="Test" DisplayMemberBinding="{Binding Path=Test}"/>
                    <GridViewColumn Header="Test2" DisplayMemberBinding="{Binding Path=Test2}"/>
            </GridView>
        </ListView.View>
    </ListView>
        <Button Content="Button" Height="63" Name="button1" Width="288" Click="button1_Click" Margin="368,388,311,12" />
</Grid>

C＃

namespace backWorkerTest
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{

    DataSet dataSet = new DataSet();
    BackgroundWorker backWorker = new BackgroundWorker();

    public MainWindow()
    {
        InitializeComponent();

        dataSet.Tables.Add("Stores");

        backWorker.DoWork += new DoWorkEventHandler(backWorker_DoWork);
        backWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backWorker_RunWorkerCompleted);

        backWorker.RunWorkerAsync();
    }

    void GetData()
    {
        using (SqlConnection con = new SqlConnection(@"Data Source=CN-LT08\Nick;Initial Catalog=SorterAdmin;" +
                                                     "User=sa; Password=Altrincham09"))
        {
            SqlDataAdapter sql = new SqlDataAdapter("SELECT [Store Number], [Store Name] FROM [Store_Info]", con);

            DataTableMapping mapping = sql.TableMappings.Add("Table", "Stores");
            mapping.ColumnMappings.Add("Store Number", "Test");
            mapping.ColumnMappings.Add("Store Name", "Test2");

            con.Open();
            sql.FillSchema(dataSet, SchemaType.Mapped);
            sql.Fill(dataSet);
            con.Close();
        }
    }

    private void button1_Click(object sender, RoutedEventArgs e)
    {
        backWorker.RunWorkerAsync();
    }

    private void backWorker_DoWork(object sender, DoWorkEventArgs e)
    {
        dataSet.Clear();
        GetData();
    }

    private void backWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        listView1.ItemsSource = dataSet.Tables["Stores"].DefaultView;
        listView1.UpdateLayout();
    }
}

}

4

3 回答 3

0

尝试刷新方法。重新绑定后。

于 2012-11-09T12:39:38.747 回答
0

更新。

如果查询相当长，则在从 SQL 读取数据时会发生错误。

为了阻止这种情况发生，我将 listView 绑定到另一个具有与旧版本 SQL 相同数据的表。现在是按钮点击事件

private void button1_Click(object sender, RoutedEventArgs e)
{

    DataTable oldTable = dataSet.Tables["Stores"].Copy();
    listView1.DataContext = oldTable.DefaultView;
    listView1.Items.Refresh();

    backWorker.RunWorkerAsync();
}
于 2012-11-09T12:50:32.627 回答
-1

@Blam你是对的。我添加了 listView1.Items.Refresh(); 到 RunComplete 事件，现在它可以工作了。

非常感谢大家的帮助。如果有人遇到同样的问题，下面是带有工作背景更新的小示例的完整代码。

C＃

namespace backWorkerTest
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{

    DataSet dataSet = new DataSet();
    BackgroundWorker backWorker = new BackgroundWorker();

    public MainWindow()
    {
        InitializeComponent();

        dataSet.Tables.Add("Stores");

        backWorker.DoWork += new DoWorkEventHandler(backWorker_DoWork);
        backWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backWorker_RunWorkerCompleted);

        backWorker.RunWorkerAsync();
    }

    #region Fill dataSet
    void GetData()
    {
        using (SqlConnection con = new SqlConnection(@"Data Source=CN-LT08\Nick;Initial Catalog=SorterAdmin;" +
                                                     "User=sa; Password=Altrincham09"))
        {
            SqlDataAdapter sql = new SqlDataAdapter("SELECT [Store Number], [Store Name] FROM [Store_Info]", con);

            DataTableMapping mapping = sql.TableMappings.Add("Table", "Stores");
            mapping.ColumnMappings.Add("Store Number", "Test");
            mapping.ColumnMappings.Add("Store Name", "Test2");

            con.Open();
            sql.FillSchema(dataSet, SchemaType.Mapped);
            sql.Fill(dataSet);
            con.Close();
        }
    }
    #endregion

    private void button1_Click(object sender, RoutedEventArgs e)
    {
        backWorker.RunWorkerAsync();
    }

    private void backWorker_DoWork(object sender, DoWorkEventArgs e)
    {
        dataSet.Clear();
        GetData();
    }

    private void backWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        listView1.ItemsSource = dataSet.Tables["Stores"].DefaultView;
        listView1.Items.Refresh();

        //MessageBox.Show("Complete");
    }
}

}

XAML

<Window x:Class="backWorkerTest.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="502" Width="989">
<Grid>
    <ListView ItemsSource="{Binding MeetCollection}" Height="340" HorizontalAlignment="Left" Margin="12,12,0,0" Name="listView1" VerticalAlignment="Top" Width="914">
        <ListView.View>
            <GridView>
                    <GridViewColumn Header="Test" DisplayMemberBinding="{Binding Path=Test}"/>
                    <GridViewColumn Header="Test2" DisplayMemberBinding="{Binding Path=Test2}"/>
            </GridView>
        </ListView.View>
    </ListView>
        <Button Content="Button" Height="63" Name="button1" Width="288" Click="button1_Click" Margin="368,388,311,12" />
</Grid>

于 2012-11-09T12:29:21.907 回答