DataBoundControl.PerformSelect 方法
定义
重要
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从关联的数据源中检索数据。
protected:
override void PerformSelect();protected override void PerformSelect ();override this.PerformSelect : unit -> unitProtected Overrides Sub PerformSelect ()示例
下面的代码示例演示如何重写 PerformSelect 该方法，以使用 GetData 该方法从关联的数据源检索数据，并将其绑定到控件的元素。 此代码示例是为类提供的大型示例的 DataBoundControl 一部分。
protected override void PerformSelect() {
// Call OnDataBinding here if bound to a data source using the
// DataSource property (instead of a DataSourceID), because the
// databinding statement is evaluated before the call to GetData.
if (! IsBoundUsingDataSourceID) {
OnDataBinding(EventArgs.Empty);
}
// The GetData method retrieves the DataSourceView object from
// the IDataSource associated with the data-bound control.
GetData().Select(CreateDataSourceSelectArguments(),
OnDataSourceViewSelectCallback);
// The PerformDataBinding method has completed.
RequiresDataBinding = false;
MarkAsDataBound();
// Raise the DataBound event.
OnDataBound(EventArgs.Empty);
}
Protected Overrides Sub PerformSelect()
' Call OnDataBinding here if bound to a data source using the
' DataSource property (instead of a DataSourceID) because the
' data-binding statement is evaluated before the call to GetData.
If Not IsBoundUsingDataSourceID Then
OnDataBinding(EventArgs.Empty)
End If
' The GetData method retrieves the DataSourceView object from the
' IDataSource associated with the data-bound control.
GetData().Select(CreateDataSourceSelectArguments(), _
AddressOf OnDataSourceViewSelectCallback)
' The PerformDataBinding method has completed.
RequiresDataBinding = False
MarkAsDataBound()
' Raise the DataBound event.
OnDataBound(EventArgs.Empty)
End Sub
注解
PerformDataBinding在检索数据以将数据绑定到数据绑定控件的元素之后调用该方法。 仅当默认实现不够时，派生类型才会重写此方法以检索数据。 通常，它足以提供执行 DataSourceViewSelectCallback 任何自定义数据工作的委托，而不是实现 PerformDataBinding 该方法。