Partial Class _Default
Inherits System.Web.UI.Page
Private m_ldSortExpression As ListDictionary
Private Property SortExpressions() As ListDictionary
Get
m_ldSortExpression = CType(ViewState("SortExpressions"), ListDictionary)
If m_ldSortExpression Is Nothing Then
m_ldSortExpression = New ListDictionary
End If
Return m_ldSortExpression
End Get
Set(ByVal value As ListDictionary)
ViewState("SortExpressions") = value
End Set
End Property
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Not IsPostBack Then
BindData()
End If
End Sub
Sub BindData()
' Usually you would get the data from the database.
' To simplify the code, I will just fill a datatable with some standard data.
Dim dt As New DataTable
dt.Columns.Add("FirstName")
dt.Columns.Add("LastName")
dt.Columns.Add("Age")
dt.Columns.Add("Position")
dt.Rows.Add(New Object() {"Sonu", "Kapoor", 28, "Developer"})
dt.Rows.Add(New Object() {"Mike", "Mustermann", 31, "IT-Lead"})
dt.Rows.Add(New Object() {"Jeff", "Kolb", 31, "IT-Lead"})
dt.Rows.Add(New Object() {"Josh", "Lucas", 37, "Support"})
dt.Rows.Add(New Object() {"Chris", "Chuck", 40, "Technical Support"})
Dim dv As DataView = dt.DefaultView
' use a stringbuilder to hold the sortexpression for the dataview
Dim sbSortExpression As New StringBuilder
If SortExpressions.Count > 0 Then
Dim myKeys(SortExpressions.Count) As String
SortExpressions.Keys.CopyTo(myKeys, 0)
For i As Integer = 0 To SortExpressions.Count - 1
sbSortExpression.Append(myKeys(i))
sbSortExpression.Append(" ")
sbSortExpression.Append(SortExpressions(myKeys(i)))
If i <> SortExpressions.Count - 1 Then
sbSortExpression.Append(", ")
End If
Next
lblSortExpression.Text = sbSortExpression.ToString
' usually we would send that sort-expression now to SQL via some stored-procedure
dv.Sort = sbSortExpression.ToString
Else
lblSortExpression.Text = String.Empty
End If
GridView1.DataSource = dv
GridView1.DataBind()
End Sub
Protected Sub GridView1_Sorting(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewSortEventArgs) Handles GridView1.Sorting
m_ldSortExpression = SortExpressions
If Not m_ldSortExpression.Contains(e.SortExpression) Then
m_ldSortExpression.Add(e.SortExpression, e.SortDirection.ToString.Replace("Ascending", "ASC").Replace("Descending", "DESC"))
Else
' Get sort direction
Dim strSortDirection As String = m_ldSortExpression.Item(e.SortExpression)
' Was it ascending?
If strSortDirection = "ASC" Then
' Yes, so sort in desc
m_ldSortExpression.Item(e.SortExpression) = "DESC"
ElseIf strSortDirection = "DESC" Then
' it is descending
' remove the sort order
m_ldSortExpression.Remove(e.SortExpression)
End If
End If
SortExpressions = m_ldSortExpression
BindData()
End Sub
End Class
