Multiple column sort of a gridview in asp.net

Most commercial applications require sorting to be integral to any gridview. You can implement multiple column sort using these instructions.

1. Add a gridview to the aspx file.

An image has been added as blog security features do not display the above code properly.

2. Include a proceudre to bind data to the gridview.

Protected Sub BindGrid()

Dim x As New Business.Employees

Dim tb As New DataTable

tb = x.GetTestTable.Tables(0)

Dim dv As DataView

dv = tb.DefaultView

If Not (GridView1.Attributes("SortExpression") Is Nothing) Then

dv.Sort = GridView1.Attributes("SortExpression")

End If

GridView1.DataSource = dv

GridView1.DataBind()

End Sub

3. Include a procedure to be called when the user clicks on the column header

Private Sub GridView1_Sorting(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewSortEventArgs) Handles GridView1.Sorting

Dim s As String

'Get existing sort expression

s = GridView1.Attributes("SortExpression")

'If the column has been included

If InStr(s, e.SortExpression.ToString()) > 0 Then

'If the column has been sorted in descending order, we remove the column from the sort expression

If InStr(s, e.SortExpression.ToString() & " DESC") > 0 Then

s = s.Replace(e.SortExpression.ToString() & " DESC", "")

s = LTrim(RTrim(s))

If s.IndexOf(",") = 0 Then

s = s.Remove(0, 1)

End If

If s.LastIndexOf(",") = (s.Length - 1) And s.Length > 0 Then

s = s.Remove(s.Length - 1, 1)

End If

s = s.Replace(",,", ",")

Else

'If the column has been sorted in ascending order, we change it to descending order

s = s.Replace(e.SortExpression.ToString(), e.SortExpression.ToString() & " DESC")

End If

Else

'If the column has not been included

If s Is Nothing Then

s = e.SortExpression.ToString()

Else

If s.Length = 0 Then

s = e.SortExpression.ToString()

Else

'If another column already exists then include the new column retaining the earlier one

s = s & "," & e.SortExpression.ToString()

End If

End If

End If

GridView1.Attributes("SortExpression") = s

BindGrid()

End Sub

4. Include a procedure to change the header based on sorting information.

Private Sub GridView1_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles GridView1.RowDataBound

If e.Row.RowType.ToString = "Header" Then

Dim i As Integer

Dim s As String

Dim lb As LinkButton

Dim img As Image

Dim sSort As String

sSort = GridView1.Attributes("SortExpression")

i = 0

While i <>

lb = e.Row.Cells(i).Controls(0)

s = lb.Text

'Insert image in cell if sorted on this field

If InStr(sSort, s) > 0 Then

img = New Image

If InStr(sSort, s & " DESC") > 0 Then

img.ImageUrl = "images/desc.png"

Else

img.ImageUrl = "images/asc.png"

End If

e.Row.Cells(i).Controls.Add(img)

End If

i = i + 1

End While

End If

End Sub

4. Obviously, you will need to call BindGrid on page load.

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

If Not Page.IsCallback Then

BindGrid()

End If

End Sub

5. When you run the form, depending on the data that is available in dt, you could get the following output.