DataBoundControl.PerformDataBinding(IEnumerable) 方法

定义

命名空间:

System.Web.UI.WebControls

程序集:

System.Web.dll

在派生类中重写时，将数据源中的数据绑定到控件。

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

从 IEnumerable 方法调用返回的数据的 PerformSelect() 列表。

示例

下面的代码示例演示如何在派生自 DataBoundControl的类中实现 PerformDataBinding 方法。 控件 TextBoxSet 为其绑定到的每个数据项创建一个 TextBox 控件。 此代码示例是为 DataBoundControl 类提供的一个更大示例的一部分。

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

从 DataBoundControl 类派生数据绑定控件时，DataBind实现此方法而不是 方法。 将 控件的数据绑定逻辑置于 中 PerformDataBinding 可以避免 DataBinding 以错误的顺序引发 和 DataBound 事件。

虽然基 DataBoundControl 类没有为此方法提供特定的实现， PerformDataBinding 但 方法会 PerformSelect 调用 方法，以将任何用户界面 (UI) 控件的值绑定到方法检索 PerformSelect 的数据。