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02.11.2008 at 12:10PM PST, ID: 23154190

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6.6

Gridview - Add/remove rows on the fly without a database

Zones: Visual Studio .NET 2005, .NET, Programming for ASP.NET

I have a gridview created blank on the fly. At the end of every row, there's an Add/Remove link button that will add/remove rows. I have one textbox field they have to enter.
As they add new rows, the text they have entered in previous rows has to be displayed. Although I see this text (in debug mode), I can't display it in the table as I loop through the gridviewrow.

The error is: "Type of value has a mismatch with column type"

Thanks

         
           
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             Here's the sub that builds a blank gridview with one row:
    Private Sub BuildUploadTable()
        Dim dt As New DataTable
        Dim dc As New DataColumn("description")
        dtFiles.Columns.Add(dc)
        Dim dr As DataRow = dtFiles.NewRow
        dr("description") = "None"
        dtFiles.Rows.Add(dr)
        dsFiles.Tables.Add(dtFiles)
        'gFiles.DataSource = dsFiles
        gvFiles.DataSource = dtFiles
        gvFiles.DataBind()
        gvFiles.Visible = True
    End Sub
 
Here's the part that's problematic:
    Protected Sub gvFiles_RowCommand(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewCommandEventArgs) Handles gvFiles.RowCommand
        If dtFiles.Rows.Count = 0 Then
            dtFiles.Columns.Add("tbDesc", GetType(TextBox))
            dtFiles.Columns.Add("Add", GetType(ButtonColumn))
            dtFiles.Columns.Add("Remove", GetType(ButtonColumn))
        End If
        'Convert datagrid to dt
        Dim gr As GridViewRow
        Dim nr As DataRow
 
        For Each gr In gvFiles.Rows
            nr = dtFiles.NewRow
'BEGIN PROBLEM
            nr(0) = CType(gr.FindControl("tbDesc"), TextBox).Text 
            nr(1) = "Add"
            nr(2) = "Remove"
'END PROBLEM
            dtFiles.Rows.Add(nr)
        Next
 
        If e.CommandName = "Add" Then
            'Add new row to dt
            nr = dtFiles.NewRow
            dtFiles.Rows.Add(nr)
            dsFiles.Tables.Add(dtFiles)
            gvFiles.DataSource = dtFiles
            gvFiles.DataBind()
            gvFiles.Visible = True
        ElseIf e.CommandName = "Remove" Then
            dtFiles.Rows.RemoveAt(gvFiles.Rows(e.CommandArgument).RowIndex)
            dsFiles.Tables.Add(dtFiles)
            gvFiles.DataSource = dtFiles
            gvFiles.DataBind()
            gvFiles.Visible = True
        End If
    End Sub

           
         

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Question Stats

Zone: Programming

Question Asked By: tucson

Solution Provided By: TheLearnedOne

Participating Experts: 1

Solution Grade: A

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02.11.2008 at 02:22PM PST, ID: 20870912

Rank: Genius

TheLearnedOne:

You should be able to add/insert rows into the DataTable datasource, and rebind to get new rows.

Bob

02.15.2008 at 02:37PM PST, ID: 20906671

tucson:

I added and removed rows successfully in the sample code above. The problem is displaying the previous row contents when a new row is added. I can see the textbox value in the table and dataset in debug mode but can't assign those values back into the gridview to be displayed.

02.15.2008 at 02:41PM PST, ID: 20906699

Rank: Genius

TheLearnedOne:

If you are correctly re-binding the GridView to the DataTable after adding a row, I don't see why it shouldn't work as expected.

Bob

02.19.2008 at 06:46AM PST, ID: 20928728

tucson:

Please look at my code snippet. I can see the values in the dataset and datatable but once I rebind it, it's not in the gridview. Thanks.

02.19.2008 at 06:52AM PST, ID: 20928830

Rank: Genius

TheLearnedOne:

I did look at your code, and I was trying to say that there is some missing bit of information to show why you are having a problem, because the code doesn't show it.

Bob

02.19.2008 at 10:29AM PST, ID: 20931099

tucson:

EnableViewState is True for the gridview.
I'm not sure what else to look for (what "missing bit"?) It doesn't show what?

02.20.2008 at 07:18AM PST, ID: 20938554

tucson:

It seems like my problem is that I'm trying to store the fileupload and textbox objects into the gridview AS WELL AS trying to store the string values of the fileupload and the textbox contents. And I can't do that? When I preview the datatable, the objects are in there but the values can't be displayed because the gridview also needs to display the objects.
I tried a placeholder but it doesn't work either.

02.20.2008 at 08:32AM PST, ID: 20939348

Rank: Genius

TheLearnedOne:

Are you saying that you have a TemplateField defined with a FileUpload control and a TextBox in the same template?

Bob

02.20.2008 at 08:39AM PST, ID: 20939439

tucson:

No they are 2 in different template columns. But I want to display the fileupload and textbox objects and their perviously entered values each time a new blank row is added.

In this example: http://geekswithblogs.net/casualjim/archive/2006/05/04/77151.aspx, you keep the fileupload/textbox objects in the footer row and adds the records into the gridview rows as labels. I want every row to be like the footer row in this example. I may just decide to to the footer row method since I'm not sure if what I'm trying to accomplish can be done in a gridview.

02.20.2008 at 09:03AM PST, ID: 20939711

Rank: Genius

TheLearnedOne:

How do you define your columns? Through the designer? In code?

You can't do this:

dtFiles.Columns.Add("Add", GetType(ButtonColumn))
dtFiles.Columns.Add("Remove", GetType(ButtonColumn))

And, then this:

nr(1) = "Add"
nr(2) = "Remove"

The type is not string, so you would need to add a ButtonColumn object. I don't think that is what you meant to do.

Bob

02.20.2008 at 09:10AM PST, ID: 20939788

tucson:

I added the columns through the designer.
The code below displays the blank rows with the appropriate controls when I added a new row.
The problem is that I can't display the values that were entered in the previous row as they add new rows. Every row is blank. The datatable and gridview only store the controls and can't display the values.
In the example below, I can't do:
nr(0) = fileU.FileName
nr(1) = tb.text, which is what I want to do.

                       
         
           
           
                    For Each gr In gFiles.Rows
            nr = dtFiles.NewRow
            fileU = CType(gr.FindControl("FileToUpload"), FileUpload)
            tb = CType(gr.FindControl("tbDesc"), TextBox)
            bAdd = CType(gr.FindControl("btnAdd"), LinkButton)
            nr(0) = fileU
            nr(1) = tb
            nr(2) = bAdd
            dtFiles.Rows.Add(nr)
        Next
            gFiles.DataSource = dtFiles
            gFiles.DataBind()
           
         

Open in New Window

02.20.2008 at 09:24AM PST, ID: 20939904

Rank: Genius

TheLearnedOne:

So, you want a dynamic number of file uploads, instead of a fixed number of rows (the usual way of doing business)?

Bob

02.20.2008 at 09:27AM PST, ID: 20939929

tucson:

Yes, because the range of number of uploads varies from 1 to 30.

02.20.2008 at 09:50AM PST, ID: 20940113

Rank: Genius

TheLearnedOne:

Does the <Add> button just insert a new row to upload? After you upload are you keeping track of the file name?

Bob

02.20.2008 at 10:26AM PST, ID: 20940441

tucson:

The upload will occur as a batch, at the very end.
Yes, the Add button adds an empty row. I need to keep track of all the previous rows already entered before finally doing a batch upload.

02.20.2008 at 10:35AM PST, ID: 20940489

Rank: Genius

TheLearnedOne:

Attached is my version of a dynamic uploader page.

Bob

02.20.2008 at 10:35AM PST, ID: 20940492

Rank: Genius

TheLearnedOne:

                       
         
           
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             <%@ Page Language="VB" AutoEventWireup="false" CodeFile="DynamicUploader.aspx.vb"
    Inherits="DynamicUploader" %>
 
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>Untitled Page</title>
    <style type="text/css">
        body { font-family: Tahoma; font-size: 10pt; }
    </style>
</head>
<body>
    <form id="form1" runat="server">
        <div>
            <asp:GridView ID="GridView1" runat="server" Height="50%" Width="100%" AutoGenerateColumns="False"
                Font-Names="Tahoma" Font-Size="10pt" OnRowCommand="GridView1_RowCommand" OnRowDataBound="GridView1_RowDataBound">
                <Columns>
                    <asp:TemplateField HeaderText="Upload">
                        <ItemTemplate>
                            <asp:FileUpload ID="FileUpload" runat="server" Font-Names="Tahoma" Font-Size="10pt"
                                Width="100%" />
                            <asp:TextBox ID="FileName" runat="server" Width="100%" Visible="false" Text='<%# Eval("FileName") %>'></asp:TextBox>
                        </ItemTemplate>
                        <HeaderStyle Width="30%" />
                    </asp:TemplateField>
                    <asp:BoundField DataField="Description" HeaderText="Description">
                        <HeaderStyle Width="40%" />
                    </asp:BoundField>
                    <asp:ButtonField CommandName="Add" Text="Add">
                        <HeaderStyle Width="5%" />
                    </asp:ButtonField>
                </Columns>
            </asp:GridView>
        </div>
    </form>
</body>
</html>

           
         

Open in New Window

02.20.2008 at 10:35AM PST, ID: 20940494

Rank: Genius

TheLearnedOne:

                       
         
           
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             Imports System
Imports System.Data
 
Partial Public Class DynamicUploader
  Inherits System.Web.UI.Page
 
  Private _UploadData As DataTable
 
  Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
 
    If Not Page.IsPostBack Then
      Me.CreateUploadTable()
    Else
      _UploadData = DirectCast(Session("UploadData"), DataTable)
    End If
 
    Me.GridView1.DataSource = _UploadData
    Me.GridView1.DataBind()
  End Sub
 
  Protected Sub GridView1_RowCommand(ByVal sender As Object, ByVal e As GridViewCommandEventArgs)
    If e.CommandName = "Add" Then
      Me.SaveUploadedFileNames()
 
      Dim dr As DataRow = _UploadData.NewRow()
 
      _UploadData.Rows.Add(dr)
 
      Session("UploadData") = _UploadData
 
      Me.GridView1.DataSource = _UploadData
      Me.GridView1.DataBind()
    End If
  End Sub
 
  Private Sub CreateUploadTable()
    _UploadData = New DataTable("Upload")
 
    _UploadData.Columns.Add("FileName")
    _UploadData.Columns.Add("Description")
 
    Dim dr As DataRow = _UploadData.NewRow()
 
    _UploadData.Rows.Add(dr)
 
    Session("UploadData") = _UploadData
  End Sub
 
  Private Sub SaveUploadedFileNames()
    For i As Integer = 0 To Me.GridView1.Rows.Count - 1
      Dim row As GridViewRow = Me.GridView1.Rows(i)
 
      Dim upload As FileUpload = TryCast(row.FindControl("FileUpload"), FileUpload)
      Dim textBox As TextBox = TryCast(row.FindControl("FileName"), TextBox)
 
      If upload IsNot Nothing AndAlso textBox IsNot Nothing AndAlso textBox.Text.Length = 0 Then
        Dim dr As DataRow = _UploadData.Rows(i)
        dr("FileName") = upload.FileName
      End If
    Next
    Session("UploadData") = _UploadData
  End Sub
 
  Protected Sub GridView1_RowDataBound(ByVal sender As Object, ByVal e As GridViewRowEventArgs)
    Dim upload As FileUpload = TryCast(e.Row.FindControl("FileUpload"), FileUpload)
    Dim textBox As TextBox = TryCast(e.Row.FindControl("FileName"), TextBox)
 
    If upload IsNot Nothing AndAlso textBox IsNot Nothing Then
      textBox.Visible = (textBox.Text.Length > 0)
      upload.Visible = Not textBox.Visible
    End If
  End Sub
End Class

           
         

Open in New Window

Accepted Solution

02.20.2008 at 11:03AM PST, ID: 20940726

tucson:

Thanks, I'm looking into this after lunch.

02.20.2008 at 01:00PM PST, ID: 20941906

tucson:

You are indeed a genius. Thank you for taking the time. You put the fileupload and a textbox in the same template column and hide/unhide the textbox. The textbox is used to store the filename for displaying it further.
Thanks

tucson

02.25.2008 at 02:04PM PST, ID: 20979722

Sorry to open this ticket again. When I upload the files at the end, what's the best way to read/write the files to upload them to the server? Since the upload control is no longer there (just the path is stored in a textbox), I can't call FileUpload.SaveAs method.
Thanks

20080236-EE-VQP-29 / EE_QW_2_20070628