Session state management provides server-based state management, where data is saved to separate browser sessions for each user.

To save the data to the session state, set the IsTrackingViewState property for the active sheet to True, as with saving data to the view state. Then handle the session state in the SaveOrLoadSheetState event.

Advantages and Disadvantages

The advantages of using the session state are:

• It offers easier implementation.
• It requires less database access.
• It can handle larger data models.
• Because the view state is small, pages load quickly.
• It enhances data durability. Data placed in session-state variables can survive Internet Information Services (IIS) restarts and worker-process restarts without losing session data because the data is stored in another process space.
• It provides platform scalability. Session state can be used in both multiple-computer and multiple-process configurations.

Using the session state is best if the data is too big to save to the view state.

The disadvantage of using the session state is the impact on performance. Session state variables stay in server memory until they are either removed or replaced, and therefore can degrade server performance. Session state variables containing blocks of information like large data sets can adversely affect Web server performance as server load increases.

Using Code

Use the session state to save data.

Example

The following sample illustrates using the session state to save data.

protected void Page_Load(object sender, System.EventArgs e)
{
if (this.IsPostBack) return;
// Connect to NWIND MS Access example with OLE DB.
OleDbConnection thisConnection = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; Data Source=D:\\NWIND.MDB");
// Open connection.
thisConnection.Open();
// Create DataSet to contain related data tables, rows, and columns.
DataSet thisDataSet = new DataSet();
OleDbDataAdapter orderAdapter = new OleDbDataAdapter("SELECT * FROM Orders", thisConnection);
orderAdapter.Fill(thisDataSet, "Orders");
FpSpread1.ActiveSheetView.IsTrackingViewState = true;
FpSpread1.ActiveSheetView.DataSource = thisDataSet;
FpSpread1.ActiveSheetView.DataMember = "Orders";
}

protected void FpSpread1_SaveOrLoadSheetState(object sender, FarPoint.Web.Spread.SheetViewStateEventArgs e)
{
if (e.IsSave)
{
Session[e.SheetView.SheetName] = e.SheetView.SaveViewState();
}
else
{
e.SheetView.LoadViewState(Session[e.SheetView.SheetName]);
}
e.Handled = true;
}

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    If (Me.IsPostBack) Then Return
    ' Connect to NWIND MS Access example with OLE DB.
     Dim thisConnection As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\NWIND.MDB")
    ' Open connection.
    thisConnection.Open()
    ' Create DataSet to contain related data tables, rows, and columns.
    Dim thisDataSet As New DataSet()
    Dim orderAdapter As New OleDbDataAdapter("SELECT * FROM Orders", thisConnection)
    orderAdapter.Fill(thisDataSet, "Orders")
    FpSpread1.ActiveSheetView.DataSource = thisDataSet
    FpSpread1.ActiveSheetView.DataMember = "Orders"
    FpSpread1.ActiveSheetView.IsTrackingViewState = True
End Sub

Private Sub FpSpread1_SaveOrLoadSheetState(ByVal sender As Object, ByVal e As FarPoint.Web.Spread.SheetViewStateEventArgs) Handles FpSpread1.SaveOrLoadSheetState
    If (e.IsSave) Then  Session(e.SheetView.SheetName) = e.SheetView.SaveViewState()
    Else
        e.SheetView.LoadViewState(Session(e.SheetView.SheetName))
    End If
    e.Handled = True
 End Sub

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