Question

我有一个ListView可以在我们的数据库中输入新的联系人，这可以正常工作，直到我将自定义属性添加到InsertItemTemplate中的文本框以提供一些JavaScript功能。

以下是ListView的片段：

    <asp:ListView ID="lvContacts" runat="server" InsertItemPosition="LastItem">
        <LayoutTemplate>
            <div id="itemPlaceholder" runat="server">
            </div>
        </LayoutTemplate>
        <ItemTemplate>
            ...
        </ItemTemplate>
        <InsertItemTemplate>
            <div class="borderedBox">
                <h3>
                    ADD OTHER CONTACT</h3>
                <div>
                    <div class="leftFields">
                        <asp:Label ID="astContactType" runat="server" CssClass="fieldLabel">Contact Type *</asp:Label><br />
                        <asp:TextBox ID="txtContactType" runat="server"></asp:TextBox><br />
                    </div>
                    <div class="rightFields">
                        <asp:Button ID="btnAdd" runat="server" Text="ADD NEW" Style="width: 150px; margin-top: 27px; margin-left: 0px;" CommandName="Insert" />
                    </div>
                    <br style="clear: both;" />
                </div>
            </div>
            ...
        </InsertItemTemplate>
    </asp:ListView>

这样可以正常工作，btnAdd命中ItemInserting函数，该函数声明如下：

Protected Sub lvContacts_ItemInserting(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.ListViewInsertEventArgs) Handles lvContacts.ItemInserting
    ...
End Sub

在ItemCreated函数中，我添加了一个“初始化”TextBox的代码，方法是添加一个带有JavaScript函数的属性，该函数有效地将虚拟文本添加到Control中，当用户点击它时会消失。但是，如果我保留此代码，则不再访问ItemInserting函数。这是ItemCreated函数：

Protected Sub lvContacts_ItemCreated(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.ListViewItemEventArgs) Handles lvContacts.ItemCreated
    Dim txtContactType As TextBox = e.Item.FindControl("txtContactType")

    ControlHelper.InitialiseTextbox(txtContactType, "Contact Type")
End Sub

(This next part is in a separate file in the App_Code folder)
Public Class ControlHelper
    Public Shared Sub InitialiseTextbox(ByVal Text As TextBox, ByVal DefaultValue As String)
        Text.Text = DefaultValue
        Text.Attributes.Add("onfocus", "textFocus('" & Text.ClientID & "', '" & DefaultValue & "')")
        Text.Attributes.Add("onblur", "textBlur('" & Text.ClientID & "', '" & DefaultValue & "')")
    End Sub
End Class

这种初始化TextBox的方法可以通过向TextBox添加属性来正常工作，TextBox也可以正常运行。当我这样做时，为什么ItemInserting不再有效？

Answer 1

在ListView控件上添加另外两个事件属性，如下所示：

 <asp:ListView ID="lvContacts" runat="server" InsertItemPosition="LastItem" 
          OnItemInserting="lvContacts_ItemInserting"
          OnItemEditing="lvContacts_ItemEditing" 
          OnPreRender="lvContacts_PreRender" >

并改变你的代码：

首先在类范围内设置一个整数变量，然后在ItemEditing事件中将索引值设置为变量，并使用pre_render事件在控件上设置属性：

Private itemIndex As Integer = -1

Protected Sub lvContacts_ItemEditing(sender As Object, e As ListViewEditEventArgs)
     itemIndex = e.NewEditIndex
End Sub

Protected Sub lvContacts_PreRender(sender As Object, e As EventArgs)
    Dim txtContactType As TextBox
    If itemIndex <> -1 Then
        txtContactType = DirectCast(ListView1.Items(itemIndex).FindControl("txtContactType"), TextBox)
        ControlHelper.InitialiseTextbox(txtContactType, "Contact Type")
    End If
End Sub

Answer 2

Ali Shahrokhi将此推向了正确的方向，当之无愧地得到了赏金。为解决此问题，我们从InitialiseTextbox部分删除了ItemCreated功能，并添加了以下内容：

Protected Sub lvContacts_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles lvContacts.PreRender
    Dim txtContactType As TextBox

    For Each item As ListViewItem In lvContacts.Items
        txtContactType = item.FindControl("txtContactType")
        ControlHelper.InitialiseTextbox(txtContactType, "Contact Type")
    Next

    txtContactType = lvContacts.InsertItem.FindControl("txtContactType")
    ControlHelper.InitialiseTextbox(txtContactType, "Contact Type")
End Sub

这将循环遍历ListView中的每个项目并将其初始化，然后初始化InsertItem的文本框。

将属性添加到TextBox后，ListView不会触发ItemInserting

2 个答案: