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GridView Control in ASP.NET: Part 1

Posted by Abhimanyu K Vatsa Articles | Visual Basic .NET November 10, 2012
In this article we will discuss on Grid View Control and its all working functions.
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Fundamentals of GridView Control

If we have data in database we can display it in Data Display controls and also can edit it. There are couples of Data Display and Edit Controls exist in ASP.Net but we will discuss on GridView here.

The GridView control is one of the most useful controls in ASP.NET. The GridView control enables us to display, select, sort, page, and edit data items such as database records.

Displaying Data

GridView control renders data items in an HTML table. Each data item is rendered in a distinct HTML table row. For example, given code will demonstrates how we use the GridView to display the contents of the database table.

  GridView1.gif

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Display Data.aspx.vb"Inherits="Display_Data" %>

<!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>Display Data</title
>
</head>
<
body>
    <form id="form1" runat="server">
    <div>
        <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" 
            DataSourceID="SqlDataSource1" 
            EmptyDataText="There are no data records to display." Width="458px">
            <Columns>
                <asp:BoundField DataField="ID" HeaderText="ID" SortExpression="ID" />
                <asp:BoundField DataField="Name" HeaderText="Name" SortExpression="Name" />
                <asp:BoundField DataField="Address" HeaderText="Address" 
                    SortExpression="Address" />
                <asp:BoundField DataField="Contact" HeaderText="Contact" 
                    SortExpression="Contact" />
            </Columns>
        </asp:GridView>
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
            ConnectionString="<%$ ConnectionStrings:DatabaseConnectionString1 %>" 
            ProviderName="<%$ ConnectionStrings:DatabaseConnectionString1.ProviderName %>" 
            SelectCommand="SELECT [ID], [Name], [Address], [Contact] FROM [MyTB]">
        </asp:SqlDataSource
>

       </div>
    </form
>
</body>
</
html>


In above code, the GridView control is bound to a SqlDataSource control, which represents the database table named MyTB. The GridView is associated with its data source through its DataSourceID property. 

We can add a GridView and SqlDataSource control to a page quickly by dragging a database table from the Database Server Explorer onto a page in Design view. It automatically creates SqlDataSource, which retrieves all the rows and all the columns from database table. 

Programmatic Data Binding

GridView control also supports programmatic data-binding. In programmatic data-binding it lists Generic collections. Notice that the GridView is bound to the myinfo list in the Page_Load() method. Its DataSource property points to the list collection, and its DataBind() method is called to load the items from the list collection and display them.

GridView2.gif

<%@ Page Language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">
    Sub Page_Load()
        ' Building list item
        Dim myinfo As New List(Of String)()
        myinfo.Add("1")
        myinfo.Add("Abhimanyu Kumar Vatsa")
        myinfo.Add("BCA Student")
        myinfo.Add("INDIA")
        ' Binding to GridView
        GridView1.DataSource = myinfo
        GridView1.DataBind()
    End 
Sub
</script>
 
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Programmatic Data Binding</title
>
</head>
<
body>
    <form id="form1" runat="server">
    <div>

        <asp:GridView ID="GridView1" runat="server">
        </asp:GridView
>

       </div>
    </form
>
</body>
</
html>

Selecting GridView

We can enable a user to select a particular row in a GridView control. This is useful when we want to build single page form for huge data. We can apply some different property to selected row to look different than other when selected. 

GridView3.gif

<%@ Page Language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
</script>
<
html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>Select Grid View</title
>
</head>
<
body>
    <form id="form1" runat="server">
    <div
>

            <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" 
            DataSourceID="SqlDataSource1" 
            EmptyDataText="There are no data records to display." Width="458px">
            <Columns>
            <asp:CommandField ShowSelectButton="True"/>
            <asp:BoundField DataField="ID" HeaderText="ID" SortExpression="ID" />
            <asp:BoundField DataField="Name" HeaderText="Name" SortExpression="Name" />
            <asp:BoundField DataField="Address" HeaderText="Address" 
                    SortExpression="Address" />
            <asp:BoundField DataField="Contact" HeaderText="Contact" 
                    SortExpression="Contact" />
            </Columns>
            <SelectedRowStyle BackColor="#336699" BorderColor="Blue" />
        </asp:GridView>
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
            ConnectionString="<%$ ConnectionStrings:DatabaseConnectionString1 %>" 
            ProviderName="<%$ ConnectionStrings:DatabaseConnectionString1.ProviderName %>" 
            SelectCommand="SELECT [ID], [Name], [Address], [Contact] FROM [MyTB]">
        </asp:SqlDataSource>
       </div>
    </form
>
</body>
</
html>

We can also enable the GridView selection using the following properties:

  • SelectedDataKey: Returns the DataKey object associated with the selected row (it is useful when there are multiple data key).
     
  • SelectedIndex: Returns the index of the selected row.
     
  • SelectedValue: Returns the data key associated with the selected row.
     
  • SelectedRow: Returns the actual row that is GridViewRow object associated with the selected row.
Using Data Keys Name

We associate a value with each row in a GridView by providing a value for the GridView control's DataKeyName property. We can assign the name of a single database column to this property or we can assign a comma-separated list of column names to this property. 

GridView4.gif

<%@ Page Language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">

</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<
head runat="server">
    <title>Using Data Keys</title>
    <style type="text/css">

    </style>
</
head>
<
body>
    <form id="form1" runat="server">
    <div>

        <asp:GridView ID="GridView1" 
        runat="server" 
        DataSourceID="SqlDataSource1" 
        DataKeyNames="Name,Address" 
        AutoGenerateSelectButton="true">
        <SelectedRowStyle CssClass="mycss" BackColor="#666699" BorderColor="Red">
        </SelectedRowStyle>
        </asp:GridView>
        <br />
        
        <br />
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
            ConnectionString="<%$ ConnectionStrings:DatabaseConnectionString1 %>" 
            SelectCommand="SELECT Name, Address FROM MyTB">
        </asp:SqlDataSource>
        <br />

      </div>
    </form>
</
body>
</
html>

Shorting Data

We can sort the rows rendered by a GridView control by enabling the AllowSorting property.

GridView5.gif

<%@ Page Language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">

</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<
head id="Head1" runat="server">
    <title></title>
    <style type="text/css">

    </style>
</
head>
<
body>
    <form id="form1" runat="server">
    <div>

        <asp:GridView ID="GridView1" 
        runat="server" 
        DataSourceID="SqlDataSource1" 
        DataKeyNames="Name,Address" 
        AutoGenerateSelectButton="true"
        AllowSorting="true">
        <SelectedRowStyle CssClass="mycss" BackColor="#666699" BorderColor="Red">
        </SelectedRowStyle>
        </asp:GridView>
        <br />

        <br />
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
            ConnectionString="<%$ ConnectionStrings:DatabaseConnectionString1 %>" 
            SelectCommand="SELECT Name, Address FROM MyTB">
        </asp:SqlDataSource>
        <br />

     </div>
    </form>
</
body>
</
html>

Note: We can do this manually using property 'AllowSorting' to true. 

Shorting with Ajax

By default, whenever we click column header to sort the rows contained in a GridView, the page containing the GridView is posted back to the server. When sorting records with the GridView control, we can avoid posting the entire page back to the server by taking advantage of AJAX (Asynchronous JavaScript and XML). 

GridView6.gif

<%
@ Page Language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<
script runat="server">
 
</script>
 
<html xmlns="http://www.w3.org/1999/xhtml">
<
head id="Head1" runat="server">
    <title>Using Data Keys</title>
    <style type="text/css">
    
    </style>
</
head>
<
body>
    <form id="form1" runat="server">
    <div>
    <div><b>Check here the time while clicking to sort.</b></div>
    <b><%= DateTime.Now.ToString("T"%></b>
    <br />
    <br />
    </div>
    <div>
    <div>
    <br />
        <b>This is with POST BACK</b>
    </div>
    <br />
        <asp:GridView ID="GridView1" 
        runat="server" 
        DataSourceID="SqlDataSource1" 
        DataKeyNames="Name,Address"
        AutoGenerateSelectButton="true"
        AllowSorting="true">
        </asp:GridView>
        <br />
        <div>
        <br />
        <br />
            <b>This is without POST BACK</b>
        </div>
        <br />
        <asp:GridView ID="GridView2" 
        runat="server" 
        DataSourceID="SqlDataSource1" 
        DataKeyNames="Name,Address" 
        EnableSortingAndPagingCallbacks="true"
        AllowSorting="true">
        </asp:GridView>
        <br />
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
            ConnectionString="<%$ ConnectionStrings:DatabaseConnectionString1 %>" 
            SelectCommand="SELECT Name, Address FROM MyTB">
        </asp:SqlDataSource>
        <br />

     </div>
    </form>
</
body>
</
html>

This page also displays the current time at the top of the page. Notice that the time is not updated when we sort the records in the GridView. The entire page is not posted back to the server; only the content of the GridView control is updated. When using AJAX with the GridView control, you cannot use TemplateFields. Furthermore, you cannot display a Select button when AJAX is enabled.

Using Image in Sorting

We can customize the appearance of the sort links by handling the GridView control's RowDataBound event. This event is raised for each row rendered by the GridView after the GridView is bound to its data source. In the example given below I have displayed an image that represent whether a column is sorted in ascending or descending order. 

<%@ Page Language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">
    Protected Sub image_RowDataBound(ByVal sender As ObjectByVal e AsGridViewRowEventArgs)
        If e.Row.RowType = DataControlRowType.Header Then
            For Each cell As TableCell In e.Row.Cells
                Dim sortLink As LinkButton = CType(cell.Controls(0), LinkButton)
                If sortLink.Text = GridView1.SortExpression Then
                    If GridView1.SortDirection = SortDirection.Ascending Then
                        sortLink.Text += " <img src='asc.GIF' title='Sort ascending' />"
                    Else
                        sortLink.Text += " <img src='desc.GIF' title='Sort descending' />"
                    End If
                End If
            Next
        End If
    End Sub
</
script>

<
html xmlns="http://www.w3.org/1999/xhtml">
<
head runat="server">
    <title></title>
</
head>
<
body>
    <form id="form1" runat="server">
    <div>

        <asp:GridView ID="GridView1" 
        runat="server" 
        DataSourceID="SqlDataSource1" 
        DataKeyNames="Name,Address" 
        AutoGenerateSelectButton="true"
        AllowSorting="true" 
        OnRowDataBound="image_RowDataBound">
        <SelectedRowStyle 
        CssClass="mycss" 
        BackColor="#666699" 
        BorderColor="Red">
        </SelectedRowStyle>
        </asp:GridView>
        <br />
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
            ConnectionString="<%$ ConnectionStrings:DatabaseConnectionString1 %>" 
            SelectCommand="SELECT Name, Address FROM MyTB">
        </asp:SqlDataSource>
        <br />
    
    </div>
    </form>
</
body>
</
html>

Sorting based on user choice

If we need to completely customize the appearance of the sorting user interface, then we can call the GridView control's Sort() method programmatically. 

GridView7.gif

<%@ Page Language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">

    Protected Sub btnSort_Click(ByVal sender As ObjectByVal e As System.EventArgs)
        GridView1.Sort(ddlSort.Text, SortDirection.Ascending)
    End Sub
</
script>

<html xmlns="http://www.w3.org/1999/xhtml">
<
head id="Head1" runat="server">
    <title></title>
    <style type="text/css">

    </style>
</
head>
<
body>
    <form id="form1" runat="server">
    <div>
    <div>
    <br />
    <asp:DropDownList
        id="ddlSort"
        Runat="server">
        <asp:ListItem Text="ID" />
        <asp:ListItem Text="Name" />
        <asp:ListItem Text="Address" />
        <asp:ListItem Text="Contact" />
    </asp:DropDownList>
    <asp:Button
        id="btnSort"
        Text="Sort"
        Runat="server" onclick="btnSort_Click" />
    <br />
    <br />
    </div>
        <asp:GridView ID="GridView1" 
        runat="server" 
        DataSourceID="SqlDataSource1"
        AutoGenerateSelectButton="true">
        <SelectedRowStyle 
        CssClass="mycss" 
        BackColor="#666699" 
        BorderColor="Red">
        </SelectedRowStyle>
        </asp:GridView>
        <br />
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
            ConnectionString="<%$ ConnectionStrings:DatabaseConnectionString1 %>" 
            SelectCommand="SELECT * FROM MyTB">
        </asp:SqlDataSource>
        <br />

    </div>
    </form>
</
body>
</
html>

Above code includes a DropDownList control, which we can use to sort the contents of the GridView. When a list item is selected from the DropDownList control and the Sort button is clicked and the btnSort_Click() method executes. This method calls the Sort() method of the GridView control to sort the contents of the GridView. 

Note: Continue in Next Part.

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