Calculations in Gridview

1. <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
2. DataKeyNames="ItemID" DataSourceID="sqlDataSource1"
3. onrowdatabound="GridView1_RowDataBound">
4. <Columns>
5. <asp:CommandField ShowDeleteButton="True" ShowEditButton="True" />
6. <asp:BoundField DataField="ItemID" HeaderText="ItemID" InsertVisible="False"
7. ReadOnly="True" SortExpression="ItemID" />
8. <asp:TemplateField HeaderText="quantity" SortExpression="quantity">
9. <EditItemTemplate>
10. <asp:TextBox ID="txtQuantity" runat="server" Text='<%# Bind("quantity") %>'></asp:TextBox>
11. </EditItemTemplate>
12. <ItemTemplate>
13. <asp:Label ID="Label1" runat="server" Text='<%# Bind("quantity") %>'></asp:Label>
14. </ItemTemplate>
15. </asp:TemplateField>
16. <asp:TemplateField HeaderText="price" SortExpression="price">
17. <EditItemTemplate>
18. <asp:TextBox ID="txtPrice" runat="server" Text='<%# Bind("price") %>'></asp:TextBox>
19. </EditItemTemplate>
20. <ItemTemplate>
21. <asp:Label ID="Label2" runat="server" Text='<%# Bind("price") %>'></asp:Label>
22. </ItemTemplate>
23. </asp:TemplateField>
24. <asp:TemplateField HeaderText="amount" SortExpression="amount">
25. <EditItemTemplate>
26. <asp:TextBox ID="txtAmount" runat="server" Text='<%# Bind("amount") %>'></asp:TextBox>
27. </EditItemTemplate>
28. <ItemTemplate>
29. <asp:Label ID="Label3" runat="server" Text='<%# Bind("amount") %>'></asp:Label>
30. </ItemTemplate>
31. </asp:TemplateField>
32. </Columns>
33. </asp:GridView>

and the RowDataBound event is

1. protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
2. {
3. if (e.Row.RowType == DataControlRowType.DataRow)
4. {
5. TextBox txtQuantity = (TextBox)e.Row.FindControl("txtQuantity");
6. TextBox txtPrice = (TextBox)e.Row.FindControl("txtPrice");
7. TextBox txtAmount = (TextBox)e.Row.FindControl("txtAmount");
8. if (txtQuantity != null)
9. {
10. txtQuantity.Attributes.Add("onkeyup", "CalcAmount('" + txtQuantity.ClientID + "','" + txtPrice.ClientID + "','" + txtAmount.ClientID + "')");
11. txtPrice.Attributes.Add("onkeyup", "CalcAmount('" + txtQuantity.ClientID + "','" + txtPrice.ClientID + "','" + txtAmount.ClientID + "')");
12. }
13. }
14. }

and the javascript method will look like this

1. <script type="text/javascript">
2. function CalcAmount(quantity, price, amount) {
3. document.getElementById(amount).value = parseFloat(document.getElementById(quantity).value) * parseFloat(document.getElementById(price).value);
4. }
6. </script>

This way when the values are changed in the quantity and price textboxes,

the corresponding amount textbox updates automatically.