Question

我想在我的WPF Datagrid中显示一个SQL表，在运行时编写SQL查询。我构建了我的View（简化）和ViewModel关联：

查看：

----------------- MyDataGrid.xaml -----------------

<DataGrid x:Name="CurrentSqlGrid" 
          ItemsSource="{Binding Path=CurrentDataTable,Mode=OneWay}"  
          Grid.Row="2" AutoGenerateColumns="True"  IsReadOnly="True" />
<TextBox x:Name="TextBoxSql" Height="120" Grid.Row="1" 
         TextWrapping="Wrap" VerticalAlignment="Top"/>

----------------- MyDataGrid.cs -----------------

public partial class MyDataGrid : UserControl
{
    private SqlDataGridViewModel sqlDataGridViewModel;

    public MyDataGrid()
    {
        InitializeComponent();
        sqlDataGridViewModel = new SqlDataGridViewModel();
        this.DataContext = sqlDataGridViewModel;
    }

    private void Button_Click_1(object sender, RoutedEventArgs e)
    {
        sqlDataGridViewModel.FillDataTableWithQuery(TextBoxSql.Text);          
    }
}

视图模型：

----------------- SqlDataGridViewModel.cs -----------------

public class SqlDataGridViewModel 
{
    private DataTable _dataTable;
    private SqlDataAdapter _adapter;

    public DataTable CurrentDataTable
    {
        get
        {
            return _dataTable;
        }
        set
        {
            _dataTable = value;
        }
    }

    public SqlDataGridViewModel()
    {
        _dataTable = new DataTable("QUERY");
        FillDataTableWithQuery("SELECT TOP 500 * FROM XUSER");           
    }

    public void FillDataTableWithQuery(string query)
    {
        CurrentDataTable.Reset();
        CurrentDataTable.Clear();

        try
        {
            using (SqlConnection sqlConn = new SqlConnection(SessionProvider.Instance.currentConnectionString))
            {
                _adapter = new SqlDataAdapter(query, sqlConn);
                _adapter.Fill(CurrentDataTable);
            }
        }
        catch (Exception ex)
        {
            MartuLogger.Instance.Error("Exception in SqlDataGridViewModel :" + ex.Message);
        }
    }
}

此解决方案首先显示第一个查询的DataTable。

但是当我编写另一个SQL查询时，我调用FillDataTableWithQuery("SELECT * from another_table")并且Datagrid清除所有行，但它不会加载新列和新行！（仅显示旧列！）。在调试中，CurrentDataTable包含新查询的结果....任何想法？

解在Faisal Hafeez的帮助下，我们找到了这个解决方案：

Xaml和后面的代码是一样的。它适用于OneWay和TwoWay模式。

我的观点模型变为：

public class SqlDataGridViewModel : INotifyPropertyChanged
{
    private DataTable _dataTable;
    private SqlDataAdapter _adapter;
    public event PropertyChangedEventHandler PropertyChanged;

    protected void NotifyPropertyChange(string PropertyName)
    {
        PropertyChanged(this, new PropertyChangedEventArgs(PropertyName));
    }

    public DataTable CurrentDataTable
    {
        get
        {
            return _dataTable;
        }
        set
        {
            _dataTable = value;
            //NotifyPropertyChange("CurrentDataTable");
        }
    }

    public SqlDataGridViewModel()
    {
        _dataTable = new DataTable("QUERY");
        FillDataTableWithQuery("SELECT TOP 500 * FROM XUSER");           
    }

    public void FillDataTableWithQuery(string query)
    {
        _dataTable = new DataTable("QUERY");

        try
        {
            using (SqlConnection sqlConn = new SqlConnection(SessionProvider.Instance.currentConnectionString))
            {
                _adapter = new SqlDataAdapter(query, sqlConn);
                _adapter.Fill(CurrentDataTable);
            }

            NotifyPropertyChange("CurrentDataTable");
        }
        catch (Exception ex)
        {
            MartuLogger.Instance.Error("Exception in SqlDataGridViewModel :" + ex.Message);
        }
    }
}

如果我在_adapter.Fill之后没有NotifyPropertyChange，则视图不会刷新。（我试图在Set CurrentTable中通知，但_adapter.Fill显然不会调用CurrentTable的set方法）。谢谢。

Answer 1

试试这个。您需要实现INotifyPropertyChanged并在datagrid的set事件上调用PropertyChanged。

public class SqlDataGridViewModel：INotifyPropertyChanged {

public event PropertyChangedEventHandler PropertyChanged;

public void OnPropertyChanged(String info)
{
    if (PropertyChanged != null)
    {
        PropertyChanged(this, new PropertyChangedEventArgs(info));
    }
}

public DataTable CurrentDataTable
    {
        get
        {
            return _dataTable;
        }
        set
        {
            _dataTable = value;
            OnPropertyChanged("CurrentDataTable");
        }
    }
}

重新加载DataFable绑定到WPF中的Datagrid

1 个答案: