ASP.NET Repeater - Summary totals

Introduction

This is my first article, hope I'm doing it correct, I don't want to bore you with too much talk, so it's pretty much code, hope it suffices. I wanted a simple and& sort of generic approach to add summary totals to the footer record of a data repeater. 

Background 

My need was for a datatable that gets bound to a Repeater, plain and simple, with a summary total for the amount and count columns for every report I had to do. The table is a report coming straight from SQL Server via my backend.  

Using the code 

I have added all the code into this one file, so you can just copy it into any ASP.NET project and just run it.

1. First we need a private variable to hold the summary totals for the fields in the table that need to be summarized. 
C#

#region - Private variables -
// This will be a list of all the fields that needs to be totalled - Dictionary<fieldName, totalValue>
private Dictionary<string, decimal> totals = new Dictionary<string, decimal>();
#endregion 

2. The next bit of code is purely to add sample data into the datatable. The data for the actual report will obviously come from your data source. 
   C#

   #region - This code belong in your backend -
   // In my framework this method is a static in a DbHelper class
   private void addDataColumn(DataTable table, string colName, string colType, bool colNull, object colDefault)
   {
       DataColumn column = new DataColumn();
       column.DataType = System.Type.GetType(colType);
       column.ColumnName = colName;
       column.AllowDBNull = colNull;
       column.DefaultValue = colDefault;
       table.Columns.Add(column);
   }
   // Here we create the sample data for this report
   private DataTable createDataTable()
   {
       // This is your variable that will hold the report data
       DataTable dtData = new DataTable();
       addDataColumn(dtData, "RecordId", "System.Int32", false, 0);
       addDataColumn(dtData, "Description", "System.String", false, 0);
       addDataColumn(dtData, "TotalCount", "System.Int32", false, 0);
       addDataColumn(dtData, "TotalAmount", "System.Decimal", false, 0);
       // Fill Table with data
       for (int i = 1; i < 6; ++i)
       {
           DataRow dr = dtData.NewRow();
           dr["RecordId"] = i;
           dr["Description"] = "Description for row " + i;
           dr["TotalCount"] = i;
           dr["TotalAmount"] = i * 3.34m;
           dtData.Rows.Add(dr);
       }
       dtData.AcceptChanges();
       return dtData;
   }
   #endregion

3. The next method is the generic part that loops the table and summarize the fields that you've added in a dictionary. Again, I've added this method to a static helper class because you can then re-use it.
   C#

   // I have this method in a static helper class
   private void sumDataTable(DataTable dt, Dictionary<string, decimal> totals)
   {
       List<string> keyList = new List<string>(totals.Keys);
       for (int i = 0; i < dt.Rows.Count; ++i)
       {
           foreach (string key in keyList)
           {
               totals[key] += Convert.ToDecimal(dt.Rows[i][key]);
           }
       }
   }  

4.  Now we have the source code specifically to the report form, starting with the page load.
   C#

   protected void Page_Load(object sender, EventArgs e)
   {
       bindTableToForm();
   } 

   and then in my bind region, we have:

1. Create and get the sample data.
2. Add the columns that needs to be totaled into the Dictionary<fieldName, startvalue>. 
3. Bind your data.  
   C#

   #region - Bind Methods -
   private void bindTableToForm()
   {
       // This is your variable that will hold the report data
       DataTable dtReport = createDataTable();
       // Do Total columns
       totals.Add("TotalCount", 0);
       totals.Add("TotalAmount", 0);
       sumDataTable(dtReport, totals);
       // 
       rprData.DataSource = dtReport;
       rprData.DataBind();
   }
   #endregion 

5. We need to add a protected / public method to the page for the Repeater to access the summary totals in the dictionary.
   C#

   #region - Public methods - 
   protected string getTotalFor(string field, string formatString)
   {
       decimal value = 0;
       totals.TryGetValue(field, out value);            
       return value.ToString(formatString);
   }
   #endregion 

6. And finally the ASP.NET HTML code:
   HTML

   <%@ Page Language="C#" AutoEventWireup="true" 
     CodeBehind="RepeaterSummaryTotal.aspx.cs" Inherits="IQ.Web.RepeaterSummaryTotal" %>
   
   <!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 runat="server">
       <title></title>
   </head>
   <body>
       <form id="form1" runat="server">
       <div>
           <div id="reportResults">
               <br />
               <asp:Repeater ID="rprData" runat="server">
                   <HeaderTemplate>
                       <table id="tblData"">
                           <thead>
                               <tr>
                                   <th colspan="4">
                                       Report sample
                                   </th>
                               </tr>
                               <tr>
                                   <td>
                                       Id.
                                   </td>
                                   <td>
                                       Description
                                   </td>
                                   <td style="text-align:right">
                                       Total count
                                   </td>
                                   <td style="text-align:right">
                                       Total amount
                                   </td>
                               </tr>
                           </thead>
                   </HeaderTemplate>
                   <ItemTemplate>
                       <tr class="even">
                           <td>
                               <%# Eval("RecordId")%>
                           </td>
                           <td>
                               <%# Eval("Description")%>
                           </td>
                           <td style="text-align:right">
                               <%# Eval("TotalCount")%>
                           </td>
                           <td style="text-align:right">
                               <%#String.Format("{0:C}", Eval("TotalAmount"))%>
                           </td>
                       </tr>
                   </ItemTemplate>
                   <AlternatingItemTemplate>
                       <tr class="odd">
                           <td>
                               <%# Eval("RecordId")%>
                           </td>
                           <td>
                               <%# Eval("Description")%>
                           </td>
                           <td style="text-align:right">
                               <%# Eval("TotalCount")%>
                           </td>
                           <td style="text-align:right">
                               <%#String.Format("{0:C}", Eval("TotalAmount"))%>
                           </td>
                       </tr>
                   </AlternatingItemTemplate>
                   <FooterTemplate>
                       <tr class="subHeadingTr" style="font-weight:bold; background-color: #e8e8e8;">
                           <td colspan="2">
                               Totals
                           </td>
                           <td style="text-align:right">
                               <%# getTotalFor("TotalCount","")%>
                           </td>
                           <td style="text-align:right">
                               <%# getTotalFor("TotalAmount","C")%>
                           </td>
                       </tr>
                       </table>
                   </FooterTemplate>
               </asp:Repeater>
           </div>    
       </div>
       </form>
   </body>
   </html>