asked on

How to calculate the sum of an unbound column in a DataGrid

I'm devloping an on-line voting system and I have a datagrid with the following columns:

CandidateID - boundcolumn and not visible
CandidateName -boundcolumn
NbrOfVotes - boundcolumn and not visible
VoterNbrOfVotes - unbound templatecolumn as asp:textbox

The user can enter any number of votes for any number of candidates as long as the total number of votes does not exceed a fixed total. I can enter values in the the unbound text box for any number of rows. But when I click the submit button I don't know how to calculate the total number of votes or determine who got how many votes. I can successfully cycle through the Items collection of the datagrid and then cycle through the Cells collection of each DataGridItem, but the unbound column is always empty no matter what I've entered on the page. I don't want the user to have to click an Edit button and enter the number of votes for each candidate that they want to vote for. Since this is my first asp.net.vb application I may be going about this all wrong, so I'd really appreciate any suggestions.

tockhoi

Did you try to iterate through the Control property of each Cell?

... Response.Write(dg.Items[1].Cells[0].Controls.Count);

The text that exists in each cell should be wrapped by a Literal control. Check if the count is greater than 0.

mmarinov

when you perform the button_Click event you can do something like this

Dim index as Integer
Dim count as Integer

For index =0 To DataGrid.Items.Count-1
Dim tb as TextBox = CType(DataGrid.Items(index).Cells(3).FindControl(the_text_box_Id), TextBox) <- 3 is get from the examle ( the 4th column, the_text_box_Id is the id of you textbox placed in the 4th column
count = count + int.Parse(tb.Text)
Next

HTH
B..G

rmk

ASKER

Here's my page:

<%@ Page Language="vb" AutoEventWireup="false" Codebehind="WCOABallot.aspx.vb" Inherits="WCSCOnLineVoting.WCOABallot"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
 <HEAD>
 <title>WCOABallot</title>
 <meta name="GENERATOR" content="Microsoft Visual Studio .NET 7.1">
 <meta name="CODE_LANGUAGE" content="Visual Basic .NET 7.1">
 <meta name="vs_defaultClientScript" content="JavaScript">
 <meta name="vs_targetSchema" content="http://schemas.microsoft.com/intellisense/ie5">
 </HEAD>
 <body MS_POSITIONING="GridLayout">
 <form id="Form1" method="post" runat="server">
 <asp:Table Runat="server" BorderStyle="Solid" BorderWidth="1" BorderColor="Red" id="Table1">
 <asp:TableRow Runat="server">
 <asp:TableCell Runat="server" HorizontalAlign="Center">
 THE WOODLANDS COMMERCIAL OWNERS ASSOCIATION, INC.
 </asp:TableCell>
 </asp:TableRow>
 <asp:TableRow Runat="server">
 <asp:TableCell Runat="server" HorizontalAlign="Center">
 BOARD OF DIRECTORS ELECTION
 </asp:TableCell>
 </asp:TableRow>
 <asp:TableRow Runat="server">
 <asp:TableHeaderCell Runat="server">
 &nbsp
 </asp:TableHeaderCell>
 </asp:TableRow>
 <asp:TableRow Runat="server">
 <asp:TableCell Runat="server" HorizontalAlign="Center">
 ELECTION OF CLASS A DIRECTOR
 </asp:TableCell>
 </asp:TableRow>
 <asp:TableRow Runat="server">
 <asp:TableHeaderCell Runat="server">
 &nbsp
 </asp:TableHeaderCell>
 </asp:TableRow>
 <asp:TableRow Runat="server">
 <asp:TableCell Runat="server" HorizontalAlign="Center">
 BALLOT
 </asp:TableCell>
 </asp:TableRow>
 <asp:TableRow Runat="server"></asp:TableRow>
 <asp:TableRow Runat="server">
 <asp:TableHeaderCell Runat="server">
 &nbsp
 </asp:TableHeaderCell>
 </asp:TableRow>
 <asp:TableRow Runat="server"></asp:TableRow>
 <asp:TableRow Runat="server">
 <asp:TableCell Runat="server" Width="100%" BorderColor="Green" BorderStyle="Solid">
 <asp:DataGrid id="dgrdBallot" runat="server" AutoGenerateColumns="false" Width="100%" HeaderStyle-BorderStyle="Solid"
 HeaderStyle-BorderColor="Black" HeaderStyle-BackColor="Green" ItemStyle-BorderStyle="Solid"
 ItemStyle-BorderColor="Black" ItemStyle-BorderWidth="1" HeaderStyle-BorderWidth="5" CellPadding="2"
 SelectedItemStyle-BackColor="Yellow" GridLines="Both" CellSpacing="2" BorderWidth="1" BorderStyle="Solid"
 BorderColor="Olive">
 <columns>
 <asp:BoundColumn HeaderText="" DataField="CandidateID" visible="False" />
 <asp:BoundColumn HeaderText="Vote for one candidate" DataField="CandidateName" />
 <asp:BoundColumn HeaderText="" DataField="CandidateVotes" visible="False" />
 <asp:templateColumn HeaderText="# Votes" HeaderStyle-HorizontalAlign="Center" ItemStyle-HorizontalAlign="Center">
 <itemtemplate>
 <asp:textbox runat="server" ID="txtCandidateVotes" Width="50" />
 </itemtemplate>
 </asp:templateColumn>
 </columns>
 </asp:DataGrid>
 </asp:TableCell>
 </asp:TableRow>
 <asp:TableRow Runat="server" Width="100%">
 <asp:TableCell Runat="server">
 Total Entitlement Votes
 </asp:TableCell>
 <asp:TableCell Runat="server" Width="50">
 <asp:Label Runat="server" ID="lblTotalVotes"></asp:Label>
 </asp:TableCell>
 </asp:TableRow>
 </asp:Table>
 <asp:Button ID="cmdSubmit" Runat="server" Text="Submit" CommandName="Submit"></asp:Button>
 
 <asp:Label ID="lblMessage" Runat="server"></asp:Label>
 </form>
 </body>
</HTML>

Here's the VB code behind:

Public Class WCOABallot
Inherits System.Web.UI.Page

#Region " Web Form Designer Generated Code "

'This call is required by the Web Form Designer.
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()

End Sub
Protected WithEvents dgrdBallot As System.Web.UI.WebControls.DataGrid
Protected WithEvents Table1 As System.Web.UI.WebControls.Table
Protected WithEvents lblMessage As System.Web.UI.WebControls.Label
Protected WithEvents cmdSubmit As System.Web.UI.WebControls.Button

'NOTE: The following placeholder declaration is required by the Web Form Designer.
'Do not delete or move it.
Private designerPlaceholderDeclaration As System.Object

Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init
'CODEGEN: This method call is required by the Web Form Designer
'Do not modify it using the code editor.
InitializeComponent()
End Sub

#End Region

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'Put user code to initialize the page here
If IsPostBack Then
Else
Dim tblCandidate As New DataTable("tblCandidate")
tblCandidate.Columns.Add("CandidateID", System.Type.GetType("System.Int32"))
tblCandidate.Columns.Add("CandidateName", System.Type.GetType("System.String"))
tblCandidate.Columns.Add("CandidateVotes", System.Type.GetType("System.Int32"))
Dim rowCandidate As DataRow
'
rowcandidate = tblCandidate.NewRow
rowCandidate("CandidateID") = 1
rowCandidate("CandidateName") = "David Kanner, Interstate Terra Development,Inc."
'rowCandidate("CandidateVotes") = Nothing
tblCandidate.Rows.Add(rowCandidate)
'
rowCandidate = tblCandidate.NewRow
rowCandidate("CandidateID") = 2
rowCandidate("CandidateName") = "Steve Sanders, Memorial Hermann Healthcare System"
'rowCandidate("CandidateVotes") = Nothing
tblCandidate.Rows.Add(rowCandidate)
'
rowCandidate = tblCandidate.NewRow
rowCandidate("CandidateID") = 3
rowCandidate("CandidateName") = "Donald R. Willis, Anadarko Petroleum"
'rowCandidate("CandidateVotes") = Nothing
tblCandidate.Rows.Add(rowCandidate)
'
dgrdBallot.DataSource = tblCandidate.DefaultView
dgrdBallot.DataBind()
End If
End Sub

Private Sub cmdSubmit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmdSubmit.Click
Dim intVotes As Int32
Dim strVotes As String
Dim fVotes As Boolean
Dim item As DataGridItem
intVotes = 0
fVotes = False
lblMessage.Text = ""
lblMessage.Text = lblMessage.Text & "items=" & dgrdBallot.Items.Count.ToString & " "
Dim intItem As Int32
For intItem = 0 To dgrdBallot.Items.Count - 1
lblMessage.Text = lblMessage.Text & "item#=" & intItem.ToString & " "
item = dgrdBallot.Items(intItem)
lblMessage.Text = lblMessage.Text & "cells=" & item.Cells.Count.ToString & " "
Dim lngCell As Int32
For lngCell = 0 To item.Cells.Count - 1
lblMessage.Text = lblMessage.Text & "cell#=" & lngCell.ToString & ";"
lblMessage.Text = lblMessage.Text & "cellText=" & item.Cells(lngCell).Text.ToString & " "
Next
Next intItem
lblMessage.Text = lblMessage.Text & " done"
End Sub
End Class

When I run the app and enter 100, 200, 300 as the votes for each candidate and then click the submit button I don't get any values for the number of votes.

ASKER CERTIFIED SOLUTION

mmarinov

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iboutchkine

Dim dr As DataRow
Dim decSum As Decimal
For Each dr In ds.Tables(t).Rows '<-- Change t to the talbe you want (t=0,1,2...)
' *** You may wnat to determine what to do whith nulls here
decSum += Convert.ToDecimal(dr.Item(c)) '<-- Change c to the column you like (0,1,2...)
Next
lblSum.Text = Convert.ToString(decSum)