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我有一个带有下拉列表的表单的面板，其值为 1-10。当按下面板上的按钮时，该面板将变为不可见，而第二个则变为可见。在第二个面板上，我动态生成了多行控件。行数由下拉列表中的选定项确定。

我的问题是，当我想执行验证然后存储动态创建的控件内容的值时，控件被删除。

我知道这与页面的生命周期和动态创建的控件的持久性有关，但我不知道要解决这个问题。我在这里阅读了许多其他类似的问题，并且很少有谁来解决这个问题的工作示例，所以我一点也不聪明。这包括需要在 pageload 或 pageinit 上创建动态创建的控件的建议，因为我们不知道要创建多少，这怎么可能？

一如既往，非常感谢任何帮助。

Imports DotNetNuke.Entities.Modules
Imports DotNetNuke
Imports System
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Collections.Generic
Imports System.Reflection
Imports System.Web.Configuration
Imports System.Net.Mail
Imports System.Data.SqlClient

Partial Class View
Inherits SeatPlannerModuleBase
Implements IActionable
Dim valid As String = "success"

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load, Me.Load
    Try

        If Not Page.IsPostBack Then

        End If

    Catch exc As Exception        'Module failed to load
        ProcessModuleLoadException(Me, exc)
    End Try
End Sub

Public ReadOnly Property ModuleActions() As Entities.Modules.Actions.ModuleActionCollection Implements Entities.Modules.IActionable.ModuleActions
    Get
        Dim Actions As New Entities.Modules.Actions.ModuleActionCollection
        Actions.Add(GetNextActionID, Localization.GetString(Entities.Modules.Actions.ModuleActionType.AddContent, LocalResourceFile), Entities.Modules.Actions.ModuleActionType.AddContent, "", "", EditUrl(), False, DotNetNuke.Security.SecurityAccessLevel.Edit, True, False)
        Return Actions
    End Get
End Property

Protected Sub Filldata()
    Dim conn As New SqlConnection()
    conn.ConnectionString = WebConfigurationManager.ConnectionStrings("Congress_SeatPlanner_ConnectionString").ConnectionString
    Dim Qstr As String = "select * From [Seat_planner_2013].[dbo].[booking]"
    Try
        Using connection As New SqlConnection(conn.ConnectionString)
            connection.Open()
            Dim command As New SqlCommand(Qstr, connection)
            Dim reader As SqlDataReader = command.ExecuteReader()
            If reader.Read() Then
                Try
                    Dim title As String

                    title = reader("title")
                    title = title.Trim
                    title_Txt.Text = title
                Catch
                    title_Txt.Text = ""
                End Try
                Try
                    first_name_Txt.Text = reader("first_name")
                Catch
                    first_name_Txt.Text = ""
                End Try
                Try
                    surname_Txt.Text = reader("surname")
                Catch
                    surname_Txt.Text = ""
                End Try
                Try
                    company_name_Txt.Text = reader("company_name")
                Catch
                    company_name_Txt.Text = ""
                End Try
                Try
                    contact_number_Txt.Text = reader("contact_phone")
                Catch
                    contact_number_Txt.Text = ""
                End Try
                Try
                    contact_email_Txt.Text = reader("contact_email")
                Catch
                    contact_email_Txt.Text = ""
                End Try
                Try
                    number_of_tickets_Ddl.SelectedValue = reader("number_of_tickets")
                Catch
                    number_of_tickets_Ddl.SelectedValue = ""
                End Try
                Try
                    purchase_date_Txt.Text = reader("date_of_purchase")
                Catch
                    purchase_date_Txt.Text = ""
                End Try
            End If
        End Using
    Catch ex As Exception
        ErrLabel_Lbl.Visible = True
        ErrLabel_Lbl.Text = ex.Message.ToString
    End Try
End Sub

Protected Sub validate()

    If title_Txt.Text.Length < 2 Then
        title_error_Lbl.Text = "Please enter a title"
        valid = "fail"
    Else
        title_error_Lbl.Text = "*"
    End If
    If first_name_Txt.Text.Length < 1 Then
        first_name_error_Lbl.Text = "Please enter a first name"
        valid = "fail"
    Else
        first_name_error_Lbl.Text = "*"
    End If
    If surname_Txt.Text.Length < 1 Then
        surname_error_Lbl.Text = "Please enter a surname"
        valid = "fail"
    Else
        surname_error_Lbl.Text = "*"
    End If
    If company_name_Txt.Text.Length < 1 Then
        comnpany_name_error_Lbl.Text = "Please enter a company name"
        valid = "fail"
    Else
        comnpany_name_error_Lbl.Text = "*"
    End If
    If contact_email_Txt.Text.Length < 1 Then
        contact_email_error_Lbl.Text = "Please enter a contact email address"
        valid = "fail"
    Else
        contact_email_error_Lbl.Text = "*"
    End If
    If contact_number_Txt.Text.Length < 1 Then
        contact_phone_error_Lbl.Text = "Please enter a contact phone number"
        valid = "fail"
    Else
        contact_phone_error_Lbl.Text = "*"
    End If
    If number_of_tickets_Ddl.SelectedValue = "Please select" Then
        number_of_tickets_error_Lbl.Text = "Please select a number of tickets to allocate"
        valid = "fail"
    Else
        number_of_tickets_error_Lbl.Text = "*"
    End If
    If purchase_date_Txt.Text.Length < 1 Then
        date_of_purchase_error_Lbl.Text = "Please enter the date you purchased the tickets"
        valid = "fail"
    Else
        date_of_purchase_error_Lbl.Text = "*"
    End If

    If valid = "fail" Then
        ErrLabel_Lbl.Text = "Failed validation"
    Else
        ErrLabel_Lbl.Text = "Validation succeeded"
    End If

End Sub

Protected Sub validate_step2()

'validation here that doesn't work due to the postback issue

End Sub

Protected Sub IterateThroughTitle(ByVal parent As Control)
    Dim count As Integer = 1

    For Each c As Control In title_Placeholder.Controls
        If c.[GetType]().ToString().Equals("System.Web.UI.WebControls.TextBox") AndAlso c.ID Is Nothing Then
            'DirectCast(c, TextBox).Text = "TextBox_Title " + count.ToString()
            DirectCast(c, TextBox).ID = "TextBox_Title_" + count.ToString()
            DirectCast(c, TextBox).CssClass = "DYN_TextBox"
            count += 1
        End If

        If c.Controls.Count > 0 Then
            IterateThroughTitle(c)
        End If
    Next
End Sub

Protected Sub IterateThroughFirstname(ByVal parent As Control)
    Dim count As Integer = 1

    For Each c As Control In firstname_Placeholder.Controls
        If c.[GetType]().ToString().Equals("System.Web.UI.WebControls.TextBox") AndAlso c.ID Is Nothing Then
            'DirectCast(c, TextBox).Text = "TextBox_Firstname " + count.ToString()
            DirectCast(c, TextBox).ID = "TextBox_Firstname_" + count.ToString()
            DirectCast(c, TextBox).CssClass = "DYN_TextBox"
            count += 1
        End If

        If c.Controls.Count > 0 Then
            IterateThroughFirstname(c)
        End If
    Next
End Sub

Protected Sub IterateThroughSurname(ByVal parent As Control)
    Dim count As Integer = 1

    For Each c As Control In surname_Placeholder.Controls
        If c.[GetType]().ToString().Equals("System.Web.UI.WebControls.TextBox") AndAlso c.ID Is Nothing Then
            'DirectCast(c, TextBox).Text = "TextBox_Surname " + count.ToString()
            DirectCast(c, TextBox).ID = "TextBox_Surname_" + count.ToString()
            DirectCast(c, TextBox).CssClass = "DYN_TextBox"
            count += 1
        End If

        If c.Controls.Count > 0 Then
            IterateThroughSurname(c)
        End If
    Next
End Sub

Protected Sub IterateThroughTicketNum(ByVal parent As Control)
    Dim count As Integer = 1

    For Each c As Control In ticketNum_Placeholder.Controls
        If c.[GetType]().ToString().Equals("System.Web.UI.WebControls.TextBox") AndAlso c.ID Is Nothing Then
            'DirectCast(c, TextBox).Text = "TextBox_TicketNum " + count.ToString()
            DirectCast(c, TextBox).ID = "TextBox_TicketNum_" + count.ToString()
            DirectCast(c, TextBox).CssClass = "DYN_TextBox"
            count += 1
        End If

        If c.Controls.Count > 0 Then
            IterateThroughTicketNum(c)
        End If
    Next
End Sub

Protected Sub IterateThroughBooking(ByVal parent As Control)
    Dim count As Integer = 1

    For Each c As Control In booking_Placeholder.Controls
        If c.[GetType]().ToString().Equals("System.Web.UI.WebControls.Label") AndAlso c.ID Is Nothing Then
            DirectCast(c, Label).Text = "Booking #" + count.ToString()
            DirectCast(c, Label).ID = "BookLabel_" + count.ToString()
            DirectCast(c, Label).CssClass = "DYN_Label"
            count += 1
        End If

        If c.Controls.Count > 0 Then
            IterateThroughBooking(c)
        End If
    Next
End Sub

Protected Sub IterateThroughReservation(ByVal parent As Control)
    Dim count As Integer = 1

    For Each c As Control In res_Placeholder.Controls
        If c.[GetType]().ToString().Equals("System.Web.UI.WebControls.Label") AndAlso c.ID Is Nothing Then
            DirectCast(c, Label).Text = "Guest"
            DirectCast(c, Label).ID = "ResLabel_" + count.ToString()
            DirectCast(c, Label).CssClass = "DYN_Label"
            count += 1
        End If

        If c.Controls.Count > 0 Then
            IterateThroughReservation(c)
        End If
    Next
End Sub

Protected Sub Retreive_first_row()

    CType(Me.FindControl("ResLabel_1"), Label).Text() = "You"
    CType(Me.FindControl("TextBox_Title_1"), TextBox).Text() = title_Txt.Text
    CType(Me.FindControl("TextBox_Title_1"), TextBox).Enabled() = False
    CType(Me.FindControl("TextBox_Firstname_1"), TextBox).Text() = first_name_Txt.Text
    CType(Me.FindControl("TextBox_Firstname_1"), TextBox).Enabled() = False
    CType(Me.FindControl("TextBox_Surname_1"), TextBox).Text() = surname_Txt.Text
    CType(Me.FindControl("TextBox_Surname_1"), TextBox).Enabled() = False

End Sub

Protected Sub CreateTextBoxes()

    If Not Page.IsValid Then
        Return
    End If

    Dim n As Integer = number_of_tickets_Ddl.SelectedValue

    For i As Integer = 0 To n - 1
        res_Placeholder.Controls.Add(New Label())
        booking_Placeholder.Controls.Add(New Label())

        title_Placeholder.Controls.Add(New TextBox())
        firstname_Placeholder.Controls.Add(New TextBox())
        surname_Placeholder.Controls.Add(New TextBox())
        ticketNum_Placeholder.Controls.Add(New TextBox())

    Next

    IterateThroughBooking(Me)
    IterateThroughReservation(Me)
    IterateThroughTitle(Me)
    IterateThroughFirstname(Me)
    IterateThroughSurname(Me)
    IterateThroughTicketNum(Me)

    Retreive_first_row()

End Sub

Protected Sub testconn_submit_Btn_Click(ByVal sender As Object, ByVal e As EventArgs) Handles testconn_submit_Btn.Click

    Filldata()

End Sub

Protected Sub next_submit_Btn_Click(ByVal sender As Object, ByVal e As EventArgs) Handles next_submit_Btn.Click

    validate()

    If valid = "fail" Then

    Else

        Step1_Pnl.Visible = False
        Step2_Pnl.Visible = True
        CreateTextBoxes()
        Button1.Attributes.Add("OnClick", "validate_step2(); return false;")
    End If

End Sub

Protected Sub clear_submit_Btn_Click(ByVal sender As Object, ByVal e As EventArgs) Handles clear_submit_Btn.Click

    title_Txt.Text = ""
    first_name_Txt.Text = ""
    surname_Txt.Text = ""
    company_name_Txt.Text = ""
    contact_number_Txt.Text = ""
    contact_email_Txt.Text = ""
    number_of_tickets_Ddl.SelectedValue = "Please select"
    purchase_date_Txt.Text = ""

    title_error_Lbl.Text = "*"
    first_name_error_Lbl.Text = "*"
    surname_error_Lbl.Text = "*"
    comnpany_name_error_Lbl.Text = "*"
    contact_phone_error_Lbl.Text = "*"
    contact_email_error_Lbl.Text = "*"
    number_of_tickets_error_Lbl.Text = "*"
    date_of_purchase_error_Lbl.Text = "*"

End Sub

Protected Sub back_Btn_Click(ByVal sender As Object, ByVal e As EventArgs) Handles back_Btn.Click

    Step1_Pnl.Visible = True
    Step2_Pnl.Visible = False

End Sub

Protected Sub next_submit2_Btn_Click(ByVal sender As Object, ByVal e As EventArgs) Handles next_submit2_Btn.Click

    validate_step2()

End Sub

End Class
4

2 回答 2

1

通常，在创建动态控件时，会在其中创建控件Page_Init并设置事件处理程序和所有初始属性（即 ID、名称、样式、文本等）。当回发发生时，ViewState 将在之后应用Page_Init（前提是 ViewState 已打开）。

在这种情况下，我将更改为中继器或某种数据网格控件并使用数据绑定来填充它。中继器控件本质上可以数据绑定到一个数字数组，重复您的模板 X 次。

可以在此处找到使用转发器执行此操作的完美示例： VB.NET Repeater Simple Data Binding without Datasource

于 2012-08-17T11:03:18.313 回答
0

当您的用户第一次在下拉列表中选择一个项目时，您将获得计数并创建动态控件。诀窍在于记住下一个计数PostBack。

您可以为此使用会话来记住此计数。

现在，当您收到第二个时PostBack，您可以重新创建控件Init。如果你想让这些动态创建的控件接收事件，那就Load太迟了。

于 2012-08-17T11:17:54.830 回答