DataBoundControl.PerformDataBinding(IEnumerable) 方法

定義

命名空間:

System.Web.UI.WebControls

組件:

System.Web.dll

在衍生類別中覆寫時，會將資料從資料來源繫結至控制項。

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)

參數

data

IEnumerable

從 IEnumerable 方法呼叫傳回之資料的 PerformSelect() 清單。

範例

下列程式碼範例示範如何在衍生自 DataBoundControl 的類別中實 PerformDataBinding 作 方法。 控制項 TextBoxSet 會 TextBox 為其系結的每個資料項目建立控制項。 此程式碼範例是提供給 類別之較大範例的 DataBoundControl 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

備註

當您從 DataBoundControl 類別衍生資料繫結控制項時， DataBind 請實作這個方法，而不是 方法。 將控制項的資料系結邏輯放在 中 PerformDataBinding ，可讓您避免 DataBinding 以錯誤順序引發 和 DataBound 事件。

雖然基 DataBoundControl 類未提供這個方法的特定實作， PerformDataBinding 但 方法會由 PerformSelect 方法呼叫，將任何使用者介面的值系結 (UI) 控制項系結至 方法所 PerformSelect 擷取的資料。