DevCurry: How to Add a Total Column to the ASP.NET ListView

A very frequently asked question about the ASP.NET ListView control is to display the sum of a column containing numeric data. In this post, I will show you how to quickly add a total's column to the ListView control. Here's how to do so by handling the ItemDataBound and PreRender event of the ListView

In your web.config, I have added a ConnectionString as shown below:

  <connectionStrings>

    <add name="NorthwindConnectionString"

         connectionString="Data Source=(local);

         Initial Catalog=Northwind;

         Integrated Security=True"

         providerName="System.Data.SqlClient"/>

  </connectionStrings>

HTML Markup

<html xmlns="http://www.w3.org/1999/xhtml">

<head runat="server">

    <title></title>

</head>

<body>

    <form id="form1" runat="server">

    <div>

<asp:ListView ID="lvProducts" runat="server" DataSourceID="SqlDataSource1"

OnItemDataBound="lvProducts_DataBound" OnPreRender="lvProducts_PreRender"

ItemPlaceholderID="PlaceHolder1">

 <LayoutTemplate>

        <asp:Placeholder

        id="PlaceHolder1"

        runat="server" />

        Total: <asp:Label ID="lblTotal" runat="server" Text="Total"/>         

    </LayoutTemplate>

<ItemTemplate>

    <asp:Label ID="lblProductName" runat="server" 

    Text='<%# Eval("ProductName") %>'/>

    <asp:Label ID="lblUnitPrice" 

    Text='<%# Eval("UnitPrice") %>' runat="server"/><br />

</ItemTemplate> 

</asp:ListView>

<asp:SqlDataSource ID="SqlDataSource1" runat="server" 

    ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>" 

    SelectCommand="SELECT [ProductID], [ProductName], [UnitPrice] FROM [Products]">

</asp:SqlDataSource>

    </div>

    </form>

</body>

</html>

double totl = 0;

protected void lvProducts_DataBound(object sender, ListViewItemEventArgs e)

{

    if (e.Item.ItemType == ListViewItemType.DataItem)

    {

        Label lblUP = e.Item.FindControl("lblUnitPrice") as Label;

        totl += Convert.ToDouble(lblUP.Text);

    }

}

protected void lvProducts_PreRender(object sender, EventArgs e)

{

    Label lblTot = this.lvProducts.FindControl("lblTotal") as Label;

    lblTot.Text = totl.ToString(); ;

}

VB.NET

    Private totl As Double = 0

    Protected Sub lvProducts_DataBound(ByVal sender As Object, ByVal e As ListViewItemEventArgs)

        If e.Item.ItemType = ListViewItemType.DataItem Then

            Dim lblUP As Label = TryCast(e.Item.FindControl("lblUnitPrice"), Label)

            totl += Convert.ToDouble(lblUP.Text)

        End If

    End Sub

    Protected Sub lvProducts_PreRender(ByVal sender As Object, ByVal e As EventArgs)

        Dim lblTot As Label = TryCast(Me.lvProducts.FindControl("lblTotal"), Label)

        lblTot.Text = totl.ToString()

    End Sub

5 comments:

AnonymousMarch 23, 2009 at 10:54 AM
Nice article.

I am getting the error "object not set an instance of object" for the following code: lblTot.Text = totl.tostring()

I believe tot1.tostring() is causing the error. I can see that tot1 has a sum of the rows.

Am I missing something?
Thanks,
hutty
AnonymousMarch 23, 2009 at 12:26 PM
Ok..I got it to work when I apply code to my original project and not the Northwind example.

What's the most efficient way to do multiple columns? The code works for the first column, but I need the other 11 columns to calculate as well.

I can copy the code twelve times, which I think is tedious.

Thanks,
Hutty
Anand Manmohan BohraNovember 28, 2011 at 4:26 AM
How come you got
protected void lvProducts_DataBound(object sender, ListViewItemEventArgs e)

in my ASP project in listview Databound has this signature

protected void LVShipment_DataBound(object sender, EventArgs e)
SikiAugust 22, 2014 at 8:11 AM
create datapager and label in listview and write the below code in C# after listview1.databind();
DataPager dp = ((DataPager)lvArrivalStatus.FindControl("dpArrivalStatusTop"));
lblArrivalCount.Text = Convert.ToString(dp.TotalRowCount);
Mike GuerraJanuary 10, 2018 at 8:07 AM
Nice Article Format!