Highlighting Rows in an ASP.Net DataGrid...
By: John Kilgo
I like the idea of highlighting rows in a DataGrid as the user scrolls the mouse up and down over the grid. The effect can be achieved using several lines of client-side JavaScript, but why do that when two lines of .Net code will accomplish the same thing? The trick is to implement an ItemDataBound event handler and add OnMouseOver and OnMouseOut attributes to handle the color change.
The code for this project is in two parts. An aspx page is used to define the datagrid and its attributes, while a .vb code-behind page is used to implement the database activity and handle the ItemDataBound method. First the .aspx page.
Notice the line OnItemDataBound="dtgCustomers_ItemDataBound". OnItemDataBound is a DataGrid method that raises the ItemDataBound event. "dtgCustomers_ItemDataBound" is the event handler which is contained in the code-behind file. One note: I chose to display rows from the NorthWind Customers table. Since this table contains over 90 rows, I also implemented paging for the datagrid. If you have used datagrids at all the rest of the attributes should be self explantory. I won't spend any more time on the .aspx page.
<%@ Page Language="vb" Src="HighlightDataGrid.aspx.vb" Inherits="HighlightDataGrid" %>
<html>
<head>
<title>Mouseover Highlighting of DataGrid Rows</title>
</head>
<body>
<form runat="server" ID="Form1">
<asp:DataGrid id="dtgCustomers"
runat="server"
OnItemDataBound="dtgCustomers_ItemDataBound"
CellPadding="4"
BackColor="White"
BorderWidth="1px"
BorderStyle="None"
BorderColor="Indigo"
AllowPaging="True"
PageSize="10"
OnPageIndexChanged="dtgCustomers_PageIndexChanged"
PagerStyle-Mode="NumericPages"
EnableViewState="False"
AutoGenerateColumns="True">
<SelectedItemStyle font-bold="True"
forecolor="#663399"
backcolor="#FFCC66">
</SelectedItemStyle>
<ItemStyle forecolor="Navy"
backcolor="White">
</ItemStyle>
<AlternatingItemStyle ForeColor="Navy"
BackColor="Yellow">
</AlternatingItemStyle>
<HeaderStyle font-bold="True"
forecolor="Navy"
backcolor="LightYellow">
</HeaderStyle>
<PagerStyle horizontalalign="Center"
forecolor="Navy"
backcolor="LightYellow">
</PagerStyle>
</asp:DataGrid>
</form>
</body>
</html>
Now for the codebehind file. The majority of the code is the typical database stuff to get the data, and to bind the data to the grid. All you see just below should again be self explanatory.
Imports System
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Data.SqlClient
Imports System.Data
Public Class HighlightDataGrid : Inherits Page
Protected dtgCustomers As DataGrid
Sub Page_Load(Sender As Object, E As System.EventArgs)
BindTheGrid()
End Sub
Sub BindTheGrid()
Dim sqlConn As New SqlConnection( _
"server=localhost;database=NorthWind;uid=sa;pwd=secret")
Dim dtaCustomers As New SqlDataAdapter( _
"Select CustomerID, CompanyName, ContactName, Phone " _
& "From Customers", sqlConn)
Dim dsCustomers As DataSet
Try
dsCustomers = New DataSet()
dtaCustomers.Fill(dsCustomers)
dtgCustomers.DataSource = dsCustomers
dtgCustomers.DataBind()
Catch SQLEx As SqlException
Response.Write(SQLEx.Message.ToString())
Catch Ex As Exception
Response.Write(Ex.Message.ToString())
Finally
sqlConn.Close()
End Try
End Sub
The code immediately below is where all the work gets done to implement the highlighting. The line within the first If block simply adds the OnMouseOver attribute to the Item changing the background color no matter whether we are in an ItemTemplate or an AlternatingItemTemplate. In the If-Then-Else block we are checking to see if we are in an ItemTemplate or an AlternatingItemTemplate and using the OnMouseOut attribute to set the background color of the row back to its original setting.
Sub dtgCustomers_ItemDataBound(sender As Object, e As DataGridItemEventArgs)
If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType = ListItemType.AlternatingItem Then
e.Item.Attributes.Add("onmouseover", "this.style.backgroundColor='Silver'")
End If
If e.Item.ItemType = ListItemType.Item Then
e.Item.Attributes.Add("onmouseout", "this.style.backgroundColor='White'")
Else
e.Item.Attributes.Add("onmouseout", "this.style.backgroundColor='Yellow'")
End If
End Sub
Sub dtgCustomers_PageIndexChanged(sender As Object, e As DataGridPageChangedEventArgs)
dtgCustomers.CurrentPageIndex = e.NewPageIndex
BindTheGrid()
End Sub
End Class
You may run the program by clicking Here.
You may download the code by clicking Here.
