来自 ASP.Net 中动态控件的回发事件的问题答案

【问题标题】：problems with postbacks events from dynamic controls in ASP.Net来自 ASP.Net 中动态控件的回发事件的问题
【发布时间】：2010-11-22 16:50:59
【问题描述】：

我目前正在处理具有构建动态表的用户控件的页面。该控件最初是在 Page_Init 事件上加载的，并且每当引发更改动态控件的事件时，都会重新加载表。这里的问题是，如果在加载之间更改控件，来自控件的事件不会触发。例如，表中最初有两行。在回发期间将一个项目添加到表中，现在有四行（此表一次添加两行）。每行有一个或两个按钮。当页面加载并发送回浏览器时，如果用户单击任何按钮，则会发生回发，但不会触发事件。我在这里做错了什么？我怎样才能知道是什么控制/事件导致了回发？下面是页面和用户控件的代码。

Payments.aspx：

Partial Public Class Payments
Inherits BasePage

Private foodMaster As Food
Private _check As BusinessLayer.CustomerCheck

Private Sub btnAddCheck_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnAddCheck.Click
    ' do nothing. the modal window is tied to the button via the modal window in the designer        
End Sub

Private Sub btnCalendar_Click(ByVal sender As Object, ByVal e As System.Web.UI.ImageClickEventArgs) Handles btnCalendar.Click
    calCheckDate.Visible = Not calCheckDate.Visible
    modCheck.Show()
End Sub

Private Sub btnCheckSave_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnCheckSave.Click
    Try
        If IsNothing(_check) Then _check = New BusinessLayer.CustomerCheck
        If Me.CurrentCheck > 0 Then _check.CheckId = Me.CurrentCheck
        _check.CheckNumber = txtCheckNumber.Text
        _check.CheckDate = CDate(txtCheckDate.Text)
        _check.CheckAmount = CDbl(txtCheckAmount.Text)
        _check.DepositId = Me.CurrentDeposit

        _check.Save()

        LoadControls()
        ' reset the current check to not get confused after an edit
        Me.CurrentCheck = 0
        SetupNewCheck()
    Catch ex As Exception
        lblMessage.Text = "Could not save check."
        lblMessage.Visible = True
        modCheck.Show()
    End Try
End Sub

Private Sub calCheckDate_SelectionChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles calCheckDate.SelectionChanged
    txtCheckDate.Text = calCheckDate.SelectedDate.ToShortDateString()
    calCheckDate.Visible = False
    modCheck.Show()
End Sub

Private Sub cvFutureDate_ServerValidate(ByVal source As Object, ByVal args As System.Web.UI.WebControls.ServerValidateEventArgs) Handles cvFutureDate.ServerValidate
    Try
        Dim depositDate As DateTime = DateTime.Parse(txtCheckDate.Text)
        Dim futureDate As DateTime = Now.AddDays(1)
        Dim tomorrow As New DateTime(futureDate.Year, futureDate.Month, futureDate.Day)

        args.IsValid = CBool(depositDate < tomorrow)
    Catch
        args.IsValid = False
    End Try
End Sub

Private Sub cvInvalidAmount_ServerValidate(ByVal source As Object, ByVal args As System.Web.UI.WebControls.ServerValidateEventArgs) Handles cvInvalidAmount.ServerValidate
    Try
        Double.Parse(txtCheckAmount.Text)
    Catch
        args.IsValid = False
    End Try
End Sub

Private Sub cvInvalidDate_ServerValidate(ByVal source As Object, ByVal args As System.Web.UI.WebControls.ServerValidateEventArgs) Handles cvInvalidDate.ServerValidate
    Try
        DateTime.Parse(txtCheckDate.Text)
    Catch
        args.IsValid = False
    End Try
End Sub

Private Sub DepositEditing()
    foodMaster.Deposit.Load(Me.CurrentDeposit)
    foodMaster.ShowDepositWindow()
End Sub

Private Sub DepositSaved()
    dihHeader.Deposit.Load(Me.CurrentDeposit)
    dihHeader.Reload()
End Sub

Private Sub Payments_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Init
    LoadControls()
End Sub

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    foodMaster = DirectCast(Me.Master, Food)
    AddHandler foodMaster.SaveClicked, AddressOf DepositSaved
    AddHandler foodMaster.EditButtonClicked, AddressOf DepositEditing

    If IsPostBack = False Then
        Me.CurrentCheck = 0
        SetupNewCheck()
    End If
End Sub

Private Sub pcPayments_ApplyFundsClicked(ByVal CheckId As Integer) Handles pcPayments.ApplyFundsClicked

End Sub

Private Sub pcPayments_DeleteClicked(ByVal CheckId As Integer) Handles pcPayments.DeleteClicked
    Try
        If Me.CurrentCheck = CheckId Then Me.CurrentCheck = 0
        _check = New BusinessLayer.CustomerCheck
        _check.CheckId = CheckId
        _check.DeleteAllPayments()
        _check.Delete()

        LoadControls()
    Catch

    End Try
End Sub

Private Sub pcPayments_EditClicked(ByVal CheckId As Integer) Handles pcPayments.EditClicked
    Me.CurrentCheck = CheckId
    _check = New BusinessLayer.CustomerCheck(CheckId)

    txtCheckAmount.Text = _check.CheckAmount.ToString("0.00")
    txtCheckDate.Text = _check.CheckDate.ToShortDateString
    calCheckDate.SelectedDate = _check.CheckDate
    txtCheckNumber.Text = _check.CheckNumber

    modCheck.Show()
End Sub

Private Sub LoadControls()
    Dim checks As New BusinessLayer.CustomerCheckCollection()
    checks.LoadByDeposit(Me.CurrentDeposit)
    pcPayments.Checks = checks
    pcPayments.Reload()

    dihHeader.Deposit.Load(Me.CurrentDeposit)
    dihHeader.TotalCheckAmount = pcPayments.TotalCheckAmount
    dihHeader.TotalAppliedAmount = pcPayments.TotalAmountApplied
    dihHeader.Reload()
End Sub

Private Sub SetupNewCheck()
    _check = Nothing
    txtCheckDate.Text = Now.ToShortDateString()
    calCheckDate.SelectedDate = Now

    txtCheckAmount.Text = String.Empty
    txtCheckNumber.Text = String.Empty
End Sub

End Class

PaymentsControl.ascx

Public Partial Class PaymentsControl
Inherits System.Web.UI.UserControl

Private _checks As BusinessLayer.CustomerCheckCollection
Private _applied As Double

Public Event ApplyFundsClicked(ByVal CheckId As Integer)
Public Event DeleteClicked(ByVal CheckId As Integer)
Public Event EditClicked(ByVal CheckId As Integer)

Public Sub New()
    _checks = New BusinessLayer.CustomerCheckCollection
    _applied = 0
End Sub

Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    'If IsPostBack = False Then
    '    BindChecks()
    'End If
End Sub

Private Sub ApplyButtonClicked(ByVal sender As Object, ByVal e As EventArgs)
    RaiseEvent ApplyFundsClicked(DirectCast(sender, LinkButton).CommandArgument)
End Sub

Private Sub DeleteButtonClicked(ByVal sender As Object, ByVal e As System.Web.UI.ImageClickEventArgs)
    RaiseEvent DeleteClicked(DirectCast(sender, ImageButton).CommandArgument)
End Sub

Private Sub EditButtonClicked(ByVal sender As Object, ByVal e As System.Web.UI.ImageClickEventArgs)
    RaiseEvent EditClicked(DirectCast(sender, ImageButton).CommandArgument)
End Sub

Private Sub BindChecks()
    tblChecks.Rows.Clear()
    tblChecks.Rows.Add(BuildTableHeader())

    _applied = 0

    For i As Int16 = 0 To _checks.Count - 1
        _checks(i).LoadAllPayments()
        _applied += _checks(i).TotalAmountApplied

        tblChecks.Rows.Add(BuildCheckRow(_checks(i)))
        tblChecks.Rows.Add(BuildInvoiceRow(_checks(i)))
    Next

    If tblChecks.Rows.Count = 1 Then tblChecks.Visible = False
End Sub

Private Function BuildCheckRow(ByVal Check As BusinessLayer.CustomerCheck) As TableRow
    Dim checkNumberCell As New TableCell()
    Dim checkDateCell As New TableCell()
    Dim checkAmountCell As New TableCell()
    Dim totalAppliedCell As New TableCell()

    checkNumberCell.Text = Check.CheckNumber
    checkDateCell.Text = Check.CheckDate.ToShortDateString()
    checkAmountCell.Text = Check.CheckAmount.ToString("C")
    totalAppliedCell.Text = Check.TotalAmountApplied.ToString("C")
    If Check.TotalAmountApplied <> Check.CheckAmount Then totalAppliedCell.ForeColor = Drawing.Color.Red

    Dim myRow As New TableRow
    myRow.Cells.Add(BuildCheckControlCell(Check.CheckId))
    myRow.Cells.Add(checkNumberCell)
    myRow.Cells.Add(checkDateCell)
    myRow.Cells.Add(checkAmountCell)
    myRow.Cells.Add(totalAppliedCell)

    Return myRow
End Function

Private Function BuildCheckControlCell(ByVal CheckId As Integer) As TableCell
    Dim editButton As New ImageButton()
    editButton.CommandArgument = CheckId
    editButton.CausesValidation = False
    editButton.AlternateText = "Edit"
    editButton.ImageUrl = "~/images/icons/bullet_edit.png"
    AddHandler editButton.Click, AddressOf EditButtonClicked

    Dim deleteButton As New ImageButton
    deleteButton.CommandArgument = CheckId
    deleteButton.CausesValidation = False
    deleteButton.AlternateText = "Delete"
    deleteButton.ImageUrl = "~/images/icons/bullet_cross.png"
    deleteButton.Attributes.Add("onclick", "return confirmDelete()")
    AddHandler deleteButton.Click, AddressOf DeleteButtonClicked

    Dim blankSpace As New Literal()
    blankSpace.Text = "&nbsp;"

    Dim myCell As New TableCell
    myCell.Controls.Add(editButton)
    myCell.Controls.Add(blankSpace)
    myCell.Controls.Add(deleteButton)

    Return myCell
End Function

Private Function BuildInvoiceRow(ByVal Check As BusinessLayer.CustomerCheck) As TableRow
    Dim invoiceDetailCell As New TableCell
    invoiceDetailCell.ColumnSpan = 4
    invoiceDetailCell.Controls.Add(BuildInvoiceDetailTable(Check.Payments))

    Dim myRow As New TableRow
    myRow.Cells.Add(BuildInvoiceControlCell(Check.CheckId))
    myRow.Cells.Add(invoiceDetailCell)

    Return myRow
End Function

Private Function BuildInvoiceControlCell(ByVal CheckId As Integer) As TableCell
    Dim text As New Literal
    text.Text = "Invoices for check:<br />"

    Dim applyButton As New LinkButton
    applyButton.CommandArgument = CheckId
    applyButton.CausesValidation = False
    applyButton.Text = "Apply Funds"
    AddHandler applyButton.Click, AddressOf ApplyButtonClicked

    Dim myCell As New TableCell
    myCell.Controls.Add(text)
    myCell.Controls.Add(applyButton)

    Return myCell
End Function

Private Function BuildInvoiceDetailTable(ByVal Payments As BusinessLayer.PaymentTransactionCollection) As Table
    Dim myTable As New Table
    myTable.CssClass = "tableSub"
    myTable.CellPadding = "0"
    myTable.CellSpacing = "0"
    myTable.BorderWidth = "0"
    myTable.Rows.Add(BuildInvoiceDetailHeader())

    For i As Integer = 0 To Payments.Count - 1
        myTable.Rows.Add(BuildPaymentRow(Payments(i)))
    Next

    If myTable.Rows.Count = 1 Then myTable.Visible = False

    Return myTable
End Function

Private Function BuildInvoiceDetailHeader() As TableRow
    Dim customerCell As New TableHeaderCell
    Dim invoiceCell As New TableHeaderCell
    Dim dueCell As New TableHeaderCell
    Dim paymentCell As New TableHeaderCell

    customerCell.Text = "Customer"
    invoiceCell.Text = "Invoice number"
    dueCell.Text = "Amount due"
    paymentCell.Text = "Payment amount"

    Dim myRow As New TableRow
    myRow.Cells.Add(customerCell)
    myRow.Cells.Add(invoiceCell)
    myRow.Cells.Add(dueCell)
    myRow.Cells.Add(paymentCell)

    Return myRow
End Function

Private Function BuildPaymentRow(ByVal Payment As BusinessLayer.PaymentTransaction) As TableRow
    Dim customerCell As New TableCell
    Dim invoiceCell As New TableCell
    Dim amountDueCell As New TableCell
    Dim paymentCell As New TableCell

    'Payment.Customer.Load()
    customerCell.Text = Payment.Customer.NumberAndName
    invoiceCell.Text = Payment.Invoice.InvoiceNumber
    amountDueCell.Text = Payment.Invoice.AmountDue.ToString("C")
    paymentCell.Text = Payment.PaymentAmount.ToString("C")

    Dim myRow As New TableRow
    myRow.Cells.Add(customerCell)
    myRow.Cells.Add(invoiceCell)
    myRow.Cells.Add(amountDueCell)
    myRow.Cells.Add(paymentCell)

    Return myRow
End Function

Private Function BuildTableHeader() As TableRow
    Dim blankCell As New TableHeaderCell()
    Dim checkNumberCell As New TableHeaderCell()
    Dim checkDateCell As New TableHeaderCell()
    Dim checkAmountCell As New TableHeaderCell()
    Dim totalUnappliedCell As New TableHeaderCell()

    checkNumberCell.Text = "Check number"
    checkDateCell.Text = "Check date"
    checkAmountCell.Text = "Check amount"
    totalUnappliedCell.Text = "Total unapplied"

    Dim myRow As New TableRow
    myRow.Cells.Add(blankCell)
    myRow.Cells.Add(checkNumberCell)
    myRow.Cells.Add(checkDateCell)
    myRow.Cells.Add(checkAmountCell)
    myRow.Cells.Add(totalUnappliedCell)

    Return myRow
End Function

Public Sub Reload()
    BindChecks()
End Sub

Public Property Checks() As BusinessLayer.CustomerCheckCollection
    Get
        Return _checks
    End Get
    Set(ByVal value As BusinessLayer.CustomerCheckCollection)
        _checks = value
    End Set
End Property

Public ReadOnly Property TotalCheckAmount() As Double
    Get
        Return _checks.TotalCheckAmount
    End Get
End Property

Public ReadOnly Property TotalAmountApplied() As Double
    Get
        Return _applied
    End Get
End Property

End Class

【问题讨论】：

标签： asp.net dynamic postback

【解决方案1】：

您需要将 Id 属性分配给每个将提供回发事件的动态添加的服务器控件。另外，在回发时，我认为需要使用相同的 id 重新创建动态添加的控件，以便回发方法和视图状态正常运行。

【讨论】：

我认为你在正确的道路上。我在想它在找到控件时遇到了问题，并且没有 id 是有道理的。但是，我不能闲置太久，所以我使用中继器重新创建了控件，并且一切正常。我想我需要将您的回复标记为答案。感谢您的帮助。