ASP.NET 魔法學院

在之前的「擴展 CommandField 類別 - 刪除提示訊息」文章中實作了 TBCommandField 類別，設定 DeleteConfirmMessage 屬性可以輕易設定刪除提示訊息。

這篇文章針對 TBCommandField 類別做進一步的擴展，我們希望在刪除訊息中可以加入指定的欄位值，讓使用者明確知道刪除的資料，例如刪除某個產品資料時，可以顯示這個產品的名稱在提示訊息中。

針對這個需求，在 TBCommandField 類別新增一個 DataField 屬性，設定刪除提示訊息中顯示欄位值的資料欄位名稱。因為要取得繫結的欄位資料，所以在 SetDeleteButton 私有方法中，設定刪除鈕 DataBinding 事件處理函式為 OnDataBindField，當 GridView 做 DataBind 時，就會引發子控制項的 DataBinding 事件，此時就會執行 OnDataBindField 方法，這時可以取得繫結的資料的 DataRowView，然後就可以從 DataRowView 中取得 DateField 的欄位值。

實作程式碼如下

Imports System Imports System.Collections.Generic Imports System.ComponentModel Imports System.Text Imports System.Web Imports System.Web.UI Imports System.Web.UI.WebControls Public Class TBCommandField Inherits CommandField Private FDeleteConfirmMessage As String = String.Empty Private FDataField As String = String.Empty ''' <summary> ''' 刪除提示訊息。 ''' </summary> Public Property DeleteConfirmMessage() As String Get Return FDeleteConfirmMessage End Get Set(ByVal value As String) FDeleteConfirmMessage = value End Set End Property ''' <summary> ''' 刪除提示訊息顯示欄位值的資料欄位名稱。 ''' </summary> Public Property DataField() As String Get Return FDataField End Get Set(ByVal value As String) FDataField = value End Set End Property ''' <summary> ''' 初始化儲存格。 ''' </summary> ''' <param name="cell">要初始化的儲存格。</param> ''' <param name="cellType">儲存格類型。</param> ''' <param name="rowState">儲存格狀態。</param> ''' <param name="rowIndex">資料列之以零起始的索引。</param> ''' <remarks></remarks> Public Overrides Sub InitializeCell(ByVal cell As DataControlFieldCell, ByVal cellType As DataControlCellType, ByVal rowState As DataControlRowState, ByVal rowIndex As Integer) MyBase.InitializeCell(cell, cellType, rowState, rowIndex) If Me.ShowDeleteButton AndAlso Me.Visible AndAlso Me.DeleteConfirmMessage <> String.Empty Then SetDeleteButton(cell) End If End Sub ''' <summary> ''' 建立新的 TBCommandField 物件。 ''' </summary> Protected Overrides Function CreateField() As DataControlField Return New TBCommandField() End Function ''' <summary> ''' 將目前 TBCommandField 物件的屬性複製到指定之 DataControlField 物件。 ''' </summary> ''' <param name="newField">目的 DataControlField 物件。</param> Protected Overrides Sub CopyProperties(ByVal NewField As DataControlField) Dim oNewField As TBCommandField oNewField = DirectCast(NewField, TBCommandField) oNewField.DeleteConfirmMessage = Me.DeleteConfirmMessage oNewField.DataField = Me.DataField MyBase.CopyProperties(NewField) End Sub ''' <summary> ''' 設定刪除鈕。 ''' </summary> ''' <param name="Cell">儲存格。</param> Private Sub SetDeleteButton(ByVal Cell As DataControlFieldCell) Dim oControl As Control For Each oControl In Cell.Controls If TypeOf (oControl) Is IButtonControl Then If DirectCast(oControl, IButtonControl).CommandName = "Delete" Then '設定刪除鈕的 DataBinding 事件處理函式 AddHandler oControl.DataBinding, New EventHandler(AddressOf Me.OnDataBindField) Exit Sub End If End If Next End Sub ''' <summary> ''' 將欄位值繫結至 TBCommandField 物件。 ''' </summary> Protected Overridable Sub OnDataBindField(ByVal sender As Object, ByVal e As EventArgs) Dim oControl As Control Dim oDataItem As Object Dim oDataRowView As Data.DataRowView Dim sScript As String Dim sMessage As String oControl = DirectCast(sender, Control) If Me.DataField <> String.Empty Then '處理訊息中的欄位值 oDataItem = DataBinder.GetDataItem(oControl.NamingContainer) oDataRowView = CType(oDataItem, Data.DataRowView) sMessage = String.Format(Me.DeleteConfirmMessage, oDataRowView.Item(Me.DataField).ToString()) Else sMessage = Me.DeleteConfirmMessage End If sMessage = Strings.Replace(sMessage, "'", "\'") '處理單引號 sScript = "if (confirm('" & sMessage & "')==false) {return false;}" DirectCast(oControl, WebControl).Attributes("onclick") = sScript End Sub End Class

使用時在 aspx 程式碼中設定其 DeleteConfirmMessage 及 DateField 屬性就在刪除提示訊息加入欄位值。其中 DeleteConfirmMessage="確定刪除 {0} 這筆資料嗎?" 中的 {0} 就是 ProductName 欄位值顯示的位置。

<bee:TBCommandField ShowDeleteButton="True" ShowEditButton="True" DataField="ProductName" DeleteConfirmMessage="確定刪除 {0} 這筆資料嗎?" ButtonType="Button" />>

執行結果如下

ASP.NET 魔法學院