如何：用 Windows 窗体 DataGrid 控件验证输入

项目
08/12/2011

提示

DataGridView 控件取代了 DataGrid 控件并添加了功能；但是，可以选择保留 DataGrid 控件以实现向后兼容并供将来使用。有关更多信息，请参见 Windows 窗体 DataGridView 控件和 DataGrid 控件之间的区别。

Windows 窗体 DataGrid 控件有两种可用的输入验证类型。如果用户尝试输入一个值，而该值具有单元格不可接受的数据类型（例如，向需要整数的单元格中输入一个字符串），则新的无效值将替换为旧值。这种输入验证是自动完成的，不能进行自定义。

另一种输入验证类型可用于拒绝任何不可接受的数据。例如，在必须大于或等于 1 的字段中输入 0 就属于不可接受的数据。此外，不合适的字符串也是不可接受的数据。这是在数据集中通过编写 ColumnChanging 或 RowChanging 事件的事件处理程序来完成的。下面的示例使用 ColumnChanging 事件，因为“Product”列不接受不允许的值。可以使用 RowChanging 事件来检查“End Date”列的值是否晚于同一行中“Start Date”列的值。

验证用户输入

编写代码以处理相应表的 ColumnChanging 事件。当检测到不适当的输入时，调用 DataRow 对象的 SetColumnError 方法。

Private Sub Customers_ColumnChanging(ByVal sender As Object, _
ByVal e As System.Data.DataColumnChangeEventArgs)
   ' Only check for errors in the Product column
   If (e.Column.ColumnName.Equals("Product")) Then
      ' Do not allow "Automobile" as a product.
      If CType(e.ProposedValue, String) = "Automobile" Then
         Dim badValue As Object = e.ProposedValue
         e.ProposedValue = "Bad Data"
         e.Row.RowError = "The Product column contians an error"
         e.Row.SetColumnError(e.Column, "Product cannot be " & _
         CType(badValue, String))
      End If
   End If
End Sub

//Handle column changing events on the Customers table
private void Customers_ColumnChanging(object sender, System.Data.DataColumnChangeEventArgs e) {

   //Only check for errors in the Product column
   if (e.Column.ColumnName.Equals("Product")) {

      //Do not allow "Automobile" as a product
      if (e.ProposedValue.Equals("Automobile")) {
         object badValue = e.ProposedValue;
         e.ProposedValue = "Bad Data";
         e.Row.RowError = "The Product column contains an error";
         e.Row.SetColumnError(e.Column, "Product cannot be " + badValue);
      }
   }
}

//Handle column changing events on the Customers table
private void Customers_ColumnChanging(System.Object sender, System.Data.DataColumnChangeEventArgs e) 
{
   //Only check for errors in the Product column
   if ( e.get_Column().get_ColumnName().Equals("Product") ) 
   {
      //Do not allow "Automobile" as a product
      if ( e.get_ProposedValue().Equals("Automobile") ) 
      {
         System.Object badValue = e.get_ProposedValue();
         e.set_ProposedValue("Bad Data");
         e.get_Row().set_RowError("The Product column contains an error");
         e.get_Row().SetColumnError(e.get_Column(), "Product cannot be " + badValue);
      }
   }
}

将事件处理程序连接到事件。

将下面的代码置于窗体的 Load 事件或其构造函数内。

' Assumes the grid is bound to a dataset called customersDataSet1
' with a table called Customers.
' Put this code in the form's Load event or its constructor.
AddHandler customersDataSet1.Tables("Customers").ColumnChanging, AddressOf Customers_ColumnChanging

// Assumes the grid is bound to a dataset called customersDataSet1
// with a table called Customers.
// Put this code in the form's Load event or its constructor.
customersDataSet1.Tables["Customers"].ColumnChanging += new DataColumnChangeEventHandler(this.Customers_ColumnChanging);

// Assumes the grid is bound to a dataset called customersDataSet1
// with a table called Customers
// Put this code in the form's Load event or its constructor.
customersDataSet1.get_Tables().get_Item("Customers").add_ColumnChanging(
   new DataColumnChangeEventHandler(this.Customers_ColumnChanging));

请参见

参考

DataGrid

ColumnChanging

SetColumnError

其他资源

DataGrid 控件（Windows 窗体）