WPF Datagrid/Datatable：大量行
我有一个连接到Datatable的Datagrid，它需要加载大量的行 为了加快速度，我加载了10%的行，并显示表单。大多数情况下，用户只需要这10%（它们是最新的条目）。在后台线程中，我将其余90%的行加载到另一个datatable（SecondData）中。然后合并两个数据表：WPF Datagrid/Datatable：大量行,wpf,performance,datagrid,datatable,rows,Wpf,Performance,Datagrid,Datatable,Rows,我有一个连接到Datatable的Datagrid，它需要加载大量的行 为了加快速度，我加载了10%的行，并显示表单。大多数情况下，用户只需要这10%（它们是最新的条目）。在后台线程中，我将其余90%的行加载到另一个datatable（SecondData）中。然后合并两个数据表： FirstData.BeginLoadData() FirstData.Merge(SecondData, False) FirstData.EndLoadData() 这很好，但是合并操作需要很长时间。如果我反转
FirstData.BeginLoadData()
FirstData.Merge(SecondData, False)
FirstData.EndLoadData()
正确的方法是什么？如果使用窗口或控件的Dispatcher属性的BeginInvoke方法，则 将委托添加到调度程序的事件队列；但是，您有机会指定 它的优先级较低。通过执行一次只加载一个项的方法，窗口 有机会在项目之间执行任何其他更高优先级的事件。这允许 控件或窗口，以便立即显示和渲染，并一次加载一个项目 下面是加载列表框的一些示例代码。
您可以根据您的数据网格进行调整。
在本例中，我使用了一个ViewModel，它包含一个ObservableCollection，其中包含一个对象。
如果您在转换到DataGrid时遇到问题，我将返工 下面是Window XAML：
<Window x:Class="ListBoxDragDrop.Views.MainView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:Models="clr-namespace:ListBoxDragDrop.Models"
Loaded="Window_Loaded"
Title="Main Window" Height="400" Width="800">
<DockPanel>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<ListBox Grid.Column="0" ItemsSource="{Binding Path=MyData}">
<ListBox.ItemTemplate>
<DataTemplate DataType="{x:Type Models:Person}">
<StackPanel>
<TextBlock Text="{Binding Name}" ></TextBlock>
<TextBlock Text="{Binding Description}" ></TextBlock>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
</DockPanel>
</Window>
下面是一个有点黑客攻击的附加版本，它演示了如何在使用still BeginInvoke绑定到DataView时加载DataGrid。 代码仍然一次加载一行到DataGrid中。 您需要根据需要进行修改；我使用加载的事件从AdventureWorks示例加载 以下是ViewModel的工作原理：
<Window x:Class="DatagridBackgroundWorker.Views.MainView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:WpfToolkit="clr-namespace:Microsoft.Windows.Controls;assembly=WPFToolkit"
Loaded="Window_Loaded"
Title="Main Window" Height="400" Width="800">
<DockPanel>
<Grid>
<WpfToolkit:DataGrid
Grid.Column="1"
SelectedItem="{Binding Path=SelectedGroup, Mode=TwoWay}"
ItemsSource="{Binding Path=GridData, Mode=OneWay}" >
</WpfToolkit:DataGrid>
</Grid>
</DockPanel>
</Window>
public class MainViewModel : ViewModelBase
{
public MainViewModel()
{
}
private ObservableCollection<Person> _myData = new ObservableCollection<Person>();
public ObservableCollection<Person> MyData
{
get
{
return _myData;
}
set
{
_myData = value;
OnPropertyChanged("MyData");
}
}
}
public class MainViewModel : ViewModelBase
{
public MainViewModel()
{
// load the connection string from the configuration files
_connectionString = ConfigurationManager.ConnectionStrings["AdventureWorks"].ConnectionString;
using (SqlConnection conn = new SqlConnection(ConnectionString))
{
conn.Open();
// load no data 1=0, but get the columns...
string query =
"SELECT [BusinessEntityID],[Name],[SalesPersonID],[Demographics],[rowguid],[ModifiedDate] FROM [Sales].[Store] Where 1=0";
SqlCommand cmd = conn.CreateCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = query;
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(_ds);
}
}
// only show grid data after button pressed...
private DataSet _ds = new DataSet("MyDataSet");
public DataView GridData
{
get
{
return _ds.Tables[0].DefaultView;
}
}
private void AddRow(SqlDataReader reader)
{
DataRow row = _ds.Tables[0].NewRow();
for (int i = 0; i < reader.FieldCount; i++)
{
row[i] = reader[i];
}
_ds.Tables[0].Rows.Add(row);
}
public void LoadData(Dispatcher dispatcher)
{
// Execute a delegate to load the first number on the UI thread, with a priority of Background.
dispatcher.BeginInvoke(DispatcherPriority.Background, new LoadNumberDelegate(LoadNumber), dispatcher, true, 1);
}
// Declare a delegate to wrap the LoadNumber method
private delegate void LoadNumberDelegate(Dispatcher dispatcher, bool first, int id);
private void LoadNumber(Dispatcher dispatcher, bool first, int id)
{
try
{
using (SqlConnection conn = new SqlConnection(ConnectionString))
{
conn.Open();
// load first 10 rows...
String query = string.Empty;
if (first)
{
// load first 10 rows
query =
"SELECT TOP 10 [BusinessEntityID],[Name],[SalesPersonID],[Demographics],[rowguid],[ModifiedDate] FROM [AdventureWorks2008].[Sales].[Store] ORDER By [BusinessEntityID]";
SqlCommand cmd = conn.CreateCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = query;
int lastId = -1;
SqlDataReader reader = cmd.ExecuteReader();
if (reader != null)
{
if (reader.HasRows)
{
while (reader.Read())
{
lastId = (int)reader["BusinessEntityID"];
AddRow(reader);
}
}
reader.Close();
}
// Load the remaining, by executing this method recursively on
// the dispatcher queue, with a priority of Background.
dispatcher.BeginInvoke(DispatcherPriority.Background,
new LoadNumberDelegate(LoadNumber), dispatcher, false, lastId);
}
else
{
// load the remaining rows...
// SIMULATE DELAY....
Thread.Sleep(5000);
query = string.Format(
"SELECT [BusinessEntityID],[Name],[SalesPersonID],[Demographics],[rowguid],[ModifiedDate] FROM [Sales].[Store] Where [BusinessEntityID] > {0} ORDER By [BusinessEntityID]",
id);
SqlCommand cmd = conn.CreateCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = query;
SqlDataReader reader = cmd.ExecuteReader();
if (reader != null)
{
if (reader.HasRows)
{
while (reader.Read())
{
AddRow(reader);
}
}
reader.Close();
}
}
}
}
catch (SqlException ex)
{
}
}
private string _connectionString = string.Empty;
public string ConnectionString
{
get { return _connectionString; }
set
{
_connectionString = value;
OnPropertyChanged("ConnectionString");
}
}
}
public类MainViewModel:ViewModelBase
{
公共主视图模型（）
{
//从配置文件加载连接字符串
_connectionString=ConfigurationManager.connectionString[“AdventureWorks”]。connectionString；
使用（SqlConnection conn=newsqlconnection（ConnectionString））
{
conn.Open（）；
//不加载数据1=0，但获取列。。。
字符串查询=
从[Sales].[Store]中选择[BusinessEntityID]、[Name]、[SalesorSonid]、[Demographics]、[rowguid]、[ModifiedDate]，其中1=0；
SqlCommand cmd=conn.CreateCommand（）；
cmd.CommandType=CommandType.Text；
cmd.CommandText=查询；
SqlDataAdapter da=新的SqlDataAdapter（cmd）；
da.填充（_ds）；
}
}
//仅在按下按钮后显示网格数据。。。
私有数据集_ds=新数据集（“MyDataSet”）；
公共数据视图网格数据
{
得到
{
返回_ds.Tables[0].DefaultView；
}
}
私有void AddRow（SqlDataReader）
{
数据行行=_ds.Tables[0].NewRow（）；
对于（int i=0；i{0}按[BusinessEntityID]排序”，
身份证）；
SqlCommand cmd=conn.CreateCommand（）；
cmd.CommandType=CommandType.Text；
cmd.CommandText=查询；
<Window x:Class="DatagridBackgroundWorker.Views.MainView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:WpfToolkit="clr-namespace:Microsoft.Windows.Controls;assembly=WPFToolkit"
Loaded="Window_Loaded"
Title="Main Window" Height="400" Width="800">
<DockPanel>
<Grid>
<WpfToolkit:DataGrid
Grid.Column="1"
SelectedItem="{Binding Path=SelectedGroup, Mode=TwoWay}"
ItemsSource="{Binding Path=GridData, Mode=OneWay}" >
</WpfToolkit:DataGrid>
</Grid>
</DockPanel>
</Window>
public partial class MainView : Window
{
ViewModels.MainViewModel _mvm = new MainViewModel();
public MainView()
{
InitializeComponent();
this.DataContext = _mvm;
}
private void Window_Loaded(object sender, RoutedEventArgs e)
{
Dispatcher d = this.Dispatcher;
_mvm.LoadData(d);
}
}
public class MainViewModel : ViewModelBase
{
public MainViewModel()
{
// load the connection string from the configuration files
_connectionString = ConfigurationManager.ConnectionStrings["AdventureWorks"].ConnectionString;
using (SqlConnection conn = new SqlConnection(ConnectionString))
{
conn.Open();
// load no data 1=0, but get the columns...
string query =
"SELECT [BusinessEntityID],[Name],[SalesPersonID],[Demographics],[rowguid],[ModifiedDate] FROM [Sales].[Store] Where 1=0";
SqlCommand cmd = conn.CreateCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = query;
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(_ds);
}
}
// only show grid data after button pressed...
private DataSet _ds = new DataSet("MyDataSet");
public DataView GridData
{
get
{
return _ds.Tables[0].DefaultView;
}
}
private void AddRow(SqlDataReader reader)
{
DataRow row = _ds.Tables[0].NewRow();
for (int i = 0; i < reader.FieldCount; i++)
{
row[i] = reader[i];
}
_ds.Tables[0].Rows.Add(row);
}
public void LoadData(Dispatcher dispatcher)
{
// Execute a delegate to load the first number on the UI thread, with a priority of Background.
dispatcher.BeginInvoke(DispatcherPriority.Background, new LoadNumberDelegate(LoadNumber), dispatcher, true, 1);
}
// Declare a delegate to wrap the LoadNumber method
private delegate void LoadNumberDelegate(Dispatcher dispatcher, bool first, int id);
private void LoadNumber(Dispatcher dispatcher, bool first, int id)
{
try
{
using (SqlConnection conn = new SqlConnection(ConnectionString))
{
conn.Open();
// load first 10 rows...
String query = string.Empty;
if (first)
{
// load first 10 rows
query =
"SELECT TOP 10 [BusinessEntityID],[Name],[SalesPersonID],[Demographics],[rowguid],[ModifiedDate] FROM [AdventureWorks2008].[Sales].[Store] ORDER By [BusinessEntityID]";
SqlCommand cmd = conn.CreateCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = query;
int lastId = -1;
SqlDataReader reader = cmd.ExecuteReader();
if (reader != null)
{
if (reader.HasRows)
{
while (reader.Read())
{
lastId = (int)reader["BusinessEntityID"];
AddRow(reader);
}
}
reader.Close();
}
// Load the remaining, by executing this method recursively on
// the dispatcher queue, with a priority of Background.
dispatcher.BeginInvoke(DispatcherPriority.Background,
new LoadNumberDelegate(LoadNumber), dispatcher, false, lastId);
}
else
{
// load the remaining rows...
// SIMULATE DELAY....
Thread.Sleep(5000);
query = string.Format(
"SELECT [BusinessEntityID],[Name],[SalesPersonID],[Demographics],[rowguid],[ModifiedDate] FROM [Sales].[Store] Where [BusinessEntityID] > {0} ORDER By [BusinessEntityID]",
id);
SqlCommand cmd = conn.CreateCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = query;
SqlDataReader reader = cmd.ExecuteReader();
if (reader != null)
{
if (reader.HasRows)
{
while (reader.Read())
{
AddRow(reader);
}
}
reader.Close();
}
}
}
}
catch (SqlException ex)
{
}
}
private string _connectionString = string.Empty;
public string ConnectionString
{
get { return _connectionString; }
set
{
_connectionString = value;
OnPropertyChanged("ConnectionString");
}
}
}