问题
I am working on a project in which I am trying to create a button dynamically in the code-behind dynamically to submit and upload a file to the server. I am using AddHandler, but the button will not post back. I read everywhere that I need to regenerate this button after each post back because of the way webpages work. I'm still not able to get this button to work. I have a main page with the HTML:
<%@ Page Language="vb"
AutoEventWireup="false"
MasterPageFile="~/Site.Master"
CodeBehind="Departments.aspx.vb"
Inherits="Homepage.Departments" %>
<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
<script type="text/javascript" src="~/Scripts/jquery-1.8.2.js"></script>
<script src="~/Scripts/jquery-ui-1.8.24.custom.min.js" type="text/javascript"></script>
<script type="text/javascript">
</script>
<div id="Top" runat="server"> </div>
<div id="Left" runat="server"></div>
<div id="Right" runat="server"></div>
</asp:Content>
The Top, Left, and Right divs are just placeholders for where I am dynamically generating the content of the page. The code-behind for the page just calls a function in a class I have developed and adds it to one of the divs on the page (I heard if I handled it in the page_init, it should create the page in the correct order...):
Protected Sub Page_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Init
*SNIP business logic to determine what information to pull*
'NewWebPart is my class that creates the custom parts and returns them as an object
For Each DeptLayoutRow As MyDataSet.DeptLayoutRow In DeptLayout
Dim NewPartObject As Object = NewWebPart.CreateNewPart
Select Case DeptLayoutRow.Area
Case 1
Top.Controls.Add(NewPartObject)
Case 2
Left.Controls.Add(NewPartObject)
Case 3
Right.Controls.Add(NewPartObject)
End Select
i += 1
Next
End If
End If
End If
End Sub
The function CreateNewWebPart is returning an object in the form of a table with a gridview, a button, and some JavaScript code inside. The important part of this class is the function that is creating the part I am having trouble with. This part contains a gridview that lists the items in a folder on the server. If the user wants, they click the upload button below the gridview and then the JavaScript creates an overlay that lets them click which file they want and upload it to the server. The submit button is the one that I am having trouble with:
Private Function CreateDocument() As Table
Dim Documents As New GridView
Documents.Width = width
Documents.Height = height
Dim table As New Table
'Dim Files As String()
Dim FileLocation As String = _
ConfigurationManager.AppSettings.Item("DeptLoc").ToString + _
"\" + DeptName + "\" + PartName
If Directory.Exists(FileLocation) Then
Dim DirInfo As New IO.DirectoryInfo(FileLocation)
Dim FileArray As IO.FileInfo() = DirInfo.GetFiles()
Dim FileInfo As IO.FileInfo
Dim Dt As New DataTable
Dt.Columns.Add("File Name", GetType(String))
Dt.Columns.Add("File Link", GetType(String))
Dt.Columns.Add("File Size", GetType(String))
Dt.Columns.Add("Last Updated", GetType(Date))
For Each FileInfo In FileArray
Dt.Rows.Add(FileInfo.Name, _
FileInfo.FullName, _
Math.Round(FileInfo.Length / 1024).ToString, _
FileInfo.LastWriteTime)
Next
Documents.DataSource = Dt
Documents.Attributes.Add("Class", "mGrid")
Documents.ID = "Documents" + IDNum.ToString
'This function creates and returns a table with Documents in the first cell
table = CreatePartTable(Documents)
'Create Upload file button'''''''''''''''''''''''''''''''''''''
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Dim btnUpload As New HtmlGenericControl
btnUpload.InnerHtml = "<button id='btnUpload" + IDNum.ToString + "'>Upload File</button>"
Dim UploadRow As New TableRow
Dim UploadRowCell As New TableCell
UploadRowCell.Controls.Add(btnUpload)
UploadRow.Cells.Add(UploadRowCell)
Dim UploadDiv As New HtmlGenericControl("DIV")
UploadDiv.ID = "UploadDiv" + IDNum.ToString
Dim lbl As New Label With {.Text = "Choose what files you would like to upload!"}
Dim FileUpload As New HtmlInputFile With {.ID = "FileUpload" + IDNum.ToString}
Dim btnSubmit As New Button With {.ID = "Submit" + IDNum.ToString, .Text = "Submit"}
'Neither of these seem to work either....
'btnSubmit.Attributes.Add("runat", "server")
'btnSubmit.Attributes.Add("onclick", "btnUploadSubmit_OnClick")
UploadDiv.Controls.Add(lbl)
UploadDiv.Controls.Add(New LiteralControl("<br />"))
UploadDiv.Controls.Add(New LiteralControl("<br />"))
UploadDiv.Controls.Add(FileUpload)
UploadDiv.Controls.Add(New LiteralControl("<br />"))
UploadDiv.Controls.Add(New LiteralControl("<br />"))
UploadDiv.Controls.Add(btnSubmit)
AddHandler btnSubmit.Click, AddressOf btnUploadSubmit_OnClick
Dim UploadDialogRow As New TableRow
Dim UploadDialogRowCell As New TableCell
UploadDialogRowCell.Controls.Add(UploadDiv)
UploadDialogRow.Cells.Add(UploadDialogRowCell)
Dim UploadDivJQuery As New UI.HtmlControls.HtmlGenericControl
Dim JQueryString As New StringBuilder
JQueryString.Append("<script type='text/javascript'>")
JQueryString.Append(" $(function() {")
JQueryString.Append(" $(""*[id$='UploadDiv" + IDNum.ToString + "']"").dialog({")
JQueryString.Append(" autoOpen: false,")
JQueryString.Append(" modal: true,")
JQueryString.Append(" show: 'clip',")
JQueryString.Append(" hide: 'clip'")
JQueryString.Append(" }); ")
JQueryString.Append(" $(""*[id$='btnUpload" + IDNum.ToString + "']"").click(function() {")
JQueryString.Append(" $(""*[id$='UploadDiv" + IDNum.ToString + "']"").dialog( 'open' );")
JQueryString.Append(" return false; ")
JQueryString.Append(" }); ")
JQueryString.Append(" });")
JQueryString.Append("</script>")
UploadDivJQuery.InnerHtml = JQueryString.ToString
Dim UploadDivJQueryRow As New TableRow
Dim UploadDivJQueryRowCell As New TableCell
UploadDivJQueryRowCell.Controls.Add(UploadDivJQuery)
UploadDivJQueryRow.Cells.Add(UploadDivJQueryRowCell)
table.Rows.Add(UploadRow)
table.Rows.Add(UploadDialogRow)
table.Rows.Add(UploadDivJQueryRow)
'To fix up the document's DataGrid the way we want it!
'This addhanlder for the documents gridview works fine...
AddHandler Documents.DataBound, AddressOf DocumentsDataGridHandler
Documents.DataBind()
End If
Return Table
End Function
Sorry if I posted too much, but I've been searching for days for an answer to this problem and can't seem to figure it out. I'm not sure if it is because I'm not loading it in the correct order, if it is because it is in another class, or of it is because I am using Master Pages or what.
来源：https://stackoverflow.com/questions/13751376/dynamic-button-not-working-with-addhandler-in-vb-net