DataBoundControl.PerformDataBinding(IEnumerable) 方法

定义

在派生类中重写时,将数据源中的数据绑定到控件。When overridden in a derived class, binds data from the data source to the control.

protected public:
 virtual void PerformDataBinding(System::Collections::IEnumerable ^ data);
protected internal virtual void PerformDataBinding (System.Collections.IEnumerable data);
abstract member PerformDataBinding : System.Collections.IEnumerable -> unit
override this.PerformDataBinding : System.Collections.IEnumerable -> unit
Protected Friend Overridable Sub PerformDataBinding (data As IEnumerable)

参数

data
IEnumerable

IEnumerable 方法调用返回的数据的 PerformSelect() 列表。The IEnumerable list of data returned from a PerformSelect() method call.

示例

下面的代码示例演示如何在从 DataBoundControl派生的类中实现 PerformDataBinding 方法。The following code example demonstrates how to implement the PerformDataBinding method in a class derived from DataBoundControl. TextBoxSet 控件将为它所绑定到的每个数据项创建 TextBox 控件。The TextBoxSet control creates a TextBox control for each data item it is bound to. 此代码示例是为 DataBoundControl 类提供的更大示例的一部分。This code example is part of a larger example provided for the DataBoundControl class.

protected override void PerformDataBinding(IEnumerable retrievedData) {
    base.PerformDataBinding(retrievedData);

    // If the data is retrieved from an IDataSource as an 
    // IEnumerable collection, attempt to bind its values to a 
    // set of TextBox controls.
    if (retrievedData != null) {

        foreach (object dataItem in retrievedData) {
            
            TextBox box = new TextBox();
            
            // The dataItem is not just a string, but potentially
            // a System.Data.DataRowView or some other container. 
            // If DataTextField is set, use it to determine which 
            // field to render. Otherwise, use the first field.                    
            if (DataTextField.Length > 0) {
                box.Text = DataBinder.GetPropertyValue(dataItem, 
                    DataTextField, null);
            }
            else {
                PropertyDescriptorCollection props = 
                    TypeDescriptor.GetProperties(dataItem);

                // Set the "default" value of the TextBox.
                box.Text = String.Empty;
                
                // Set the true data-bound value of the TextBox,
                // if possible.
                if (props.Count >= 1) {                        
                    if (null != props[0].GetValue(dataItem)) {
                        box.Text = props[0].GetValue(dataItem).ToString();
                    }
                }
            }                                        
            
            BoxSet.Add(box);
        }
    }
}
Protected Overrides Sub PerformDataBinding(ByVal retrievedData As IEnumerable)
    MyBase.PerformDataBinding(retrievedData)

    ' If the data is retrieved from an IDataSource as an IEnumerable 
    ' collection, attempt to bind its values to a set of TextBox controls.
    If Not (retrievedData Is Nothing) Then

        Dim dataItem As Object
        For Each dataItem In retrievedData

            Dim box As New TextBox()

            ' The dataItem is not just a string, but potentially
            ' a System.Data.DataRowView or some other container. 
            ' If DataTextField is set, use it to determine which 
            ' field to render. Otherwise, use the first field.                    
            If DataTextField.Length > 0 Then
                box.Text = DataBinder.GetPropertyValue( _
                dataItem, DataTextField, Nothing)
            Else
                Dim props As PropertyDescriptorCollection = _
                    TypeDescriptor.GetProperties(dataItem)

                ' Set the "default" value of the TextBox.
                box.Text = String.Empty

                ' Set the true data-bound value of the TextBox,
                ' if possible.
                If props.Count >= 1 Then
                    If props(0).GetValue(dataItem) IsNot Nothing Then
                        box.Text = props(0).GetValue(dataItem).ToString()
                    End If
                End If
            End If

            BoxSet.Add(box)
        Next dataItem
    End If

End Sub

注解

DataBoundControl 类派生数据绑定控件时,实现此方法而不是 DataBind 方法。Implement this method instead of the DataBind method when you derive a data-bound control from the DataBoundControl class. 通过在 PerformDataBinding 中放置控件的数据绑定逻辑,您可以避免按错误的顺序引发 DataBindingDataBound 事件。Placing your control's data-binding logic in PerformDataBinding enables you to avoid the DataBinding and DataBound events being raised in the wrong order.

虽然 base DataBoundControl 类不提供此方法的特定实现,但 PerformSelect 方法会调用 PerformDataBinding 方法将任何用户界面(UI)控件的值绑定到 PerformSelect 方法检索的数据。While the base DataBoundControl class provides no specific implementation for this method, the PerformDataBinding method is called by the PerformSelect method to bind the values of any user interface (UI) controls to the data that is retrieved by the PerformSelect method.

适用于