Persist the state of expanded items in Hierarchical Grid

Environment

Product	RadPersistenceFramework for ASP.NET AJAX

Description

I want to persist the layout of a RadGrid with detail tables using the RadPersistenceManager. The layout is being persisted for the main grid, but not for the hierarchy/detail tables.

Solution

The RadPersistenceFramework does not support persistence out of the box for hierarchy and detail tables (see Supported Controls). However, you can manually save and restore the state of these tables by using Custom Settings.

Here's an example of how to save and restore the expanded state of rows for all tables in the Grid Hierarchy:

1. Add RadPersistenceManager control to your page with the following settings:

• Specify a key for the StorageProviderKey property
• Attach the OnSaveSettings event.
• Attach the OnLoadSettings event.
• Add the Grid to the PersistenceSettings.

<telerik:RadPersistenceManager ID="RadPersistenceManager1" runat="server" 
    StorageProviderKey="MyStorageKey"
    OnSaveSettings="RadPersistenceManager1_SaveSettings" 
    OnLoadSettings="RadPersistenceManager1_LoadSettings">
    <PersistenceSettings>
        <telerik:PersistenceSetting ControlID="RadGrid1" />
    </PersistenceSettings>
</telerik:RadPersistenceManager>

2. Create a method that will collect the index of expanded items in the Hierarchical Grid recursively and saves those in the Grid's ControlState as Custom Settings.

private void SaveExpandedStateRecursive(GridTableView tableView, RadControlState customSettings)
{
    List<int> expandedIndexes = new List<int>();

    foreach (GridDataItem item in tableView.Items)
    {
        if (item.Expanded)
        {
            expandedIndexes.Add(item.ItemIndex);

            GridNestedViewItem nestedViewItem = item.ChildItem;

            foreach (GridTableView detailTable in nestedViewItem.NestedTableViews)
            {
                SaveExpandedStateRecursive(detailTable, customSettings);
            }
        }
    }

    string settingsName = string.Format("{0}_{1}_ExpandedItems", tableView.Name, tableView.ID);

    customSettings.ControlSettings.Add(new ControlSetting() { Name = settingsName, Value = expandedIndexes });
}

Private Sub SaveExpandedStateRecursive(ByVal tableView As GridTableView, ByVal customSettings As RadControlState)
    Dim expandedIndexes As List(Of Integer) = New List(Of Integer)()

    For Each item As GridDataItem In tableView.Items

        If item.Expanded Then
            expandedIndexes.Add(item.ItemIndex)
            Dim nestedViewItem As GridNestedViewItem = item.ChildItem

            For Each detailTable As GridTableView In nestedViewItem.NestedTableViews
                SaveExpandedStateRecursive(detailTable, customSettings)
            Next
        End If
    Next

    Dim settingsName As String = String.Format("{0}_{1}_ExpandedItems", tableView.Name, tableView.ID)

    customSettings.ControlSettings.Add(New ControlSetting() With {
        .Name = settingsName,
        .Value = expandedIndexes
    })
End Sub

3. Create a method that will restore the expanded state from the Custom Settings for all items recursively in the Hierarchical Grid.

private void RestoreExpandedStateRecursive(GridTableView tableView, RadControlState customSettings)
{
    string settingsName = string.Format("{0}_{1}_ExpandedItems", tableView.Name, tableView.ID);

    ControlSetting tableSettings = customSettings.ControlSettings.Where(s => s.Name == settingsName).FirstOrDefault();
    List<int> expandedIndexes = (List<int>) tableSettings.Value;

    foreach (int itemIndex in expandedIndexes)
    {
        GridDataItem itemToExpand = tableView.Items[itemIndex];

        itemToExpand.Expanded = true;

        GridNestedViewItem nestedViewItem = itemToExpand.ChildItem;

        if (nestedViewItem != null)
        {
            foreach (GridTableView detailTable in nestedViewItem.NestedTableViews)
            {
                RestoreExpandedStateRecursive(detailTable, customSettings);
            }
        }
    }
}

Private Sub RestoreExpandedStateRecursive(ByVal tableView As GridTableView, ByVal customSettings As RadControlState)
    Dim settingsName As String = String.Format("{0}_{1}_ExpandedItems", tableView.Name, tableView.ID)
    Dim tableSettings As ControlSetting = customSettings.ControlSettings.Where(Function(s) s.Name = settingsName).FirstOrDefault()
    Dim expandedIndexes As List(Of Integer) = CType(tableSettings.Value, List(Of Integer))

    For Each itemIndex As Integer In expandedIndexes
        Dim itemToExpand As GridDataItem = tableView.Items(itemIndex)
        itemToExpand.Expanded = True
        Dim nestedViewItem As GridNestedViewItem = itemToExpand.ChildItem

        If nestedViewItem IsNot Nothing Then

            For Each detailTable As GridTableView In nestedViewItem.NestedTableViews
                RestoreExpandedStateRecursive(detailTable, customSettings)
            Next
        End If
    Next
End Sub

4. Implement the necessary code to handle the save and restore events of the Persistence Framework.

protected void RadPersistenceManager1_SaveSettings(object sender, PersistenceManagerSaveAllStateEventArgs e)
{
    RadControlState gridSetting = e.Settings.FindByUniqueId(RadGrid1.UniqueID);

    if (gridSetting != null)
    {
        SaveExpandedStateRecursive(RadGrid1.MasterTableView, gridSetting);
    }
}

protected void RadPersistenceManager1_LoadSettings(object sender, PersistenceManagerLoadAllStateEventArgs e)
{
    RadControlState gridSetting = e.Settings.FindByUniqueId(RadGrid1.UniqueID);

    if (gridSetting != null)
    {
        RestoreExpandedStateRecursive(RadGrid1.MasterTableView, gridSetting);
    }
}

Protected Sub RadPersistenceManager1_SaveSettings(ByVal sender As Object, ByVal e As PersistenceManagerSaveAllStateEventArgs)
    Dim gridSetting As RadControlState = e.Settings.FindByUniqueId(RadGrid1.UniqueID)

    If gridSetting IsNot Nothing Then
        SaveExpandedStateRecursive(RadGrid1.MasterTableView, gridSetting)
    End If
End Sub

Protected Sub RadPersistenceManager1_LoadSettings(ByVal sender As Object, ByVal e As PersistenceManagerLoadAllStateEventArgs)
    Dim gridSetting As RadControlState = e.Settings.FindByUniqueId(RadGrid1.UniqueID)

    If gridSetting IsNot Nothing Then
        RestoreExpandedStateRecursive(RadGrid1.MasterTableView, gridSetting)
    End If
End Sub

5. Finally, to save and restore those settings call the SaveState() and LoadState() methods of the PersistenceManager respectively.

protected void btnSave_Click(object sender, EventArgs e)
{
    RadPersistenceManager1.SaveState();
}

protected void btnRestore_Click(object sender, EventArgs e)
{
    RadPersistenceManager1.LoadState();
    RadGrid1.Rebind();
}

Protected Sub btnSave_Click(ByVal sender As Object, ByVal e As EventArgs)
    RadPersistenceManager1.SaveState()
End Sub

Protected Sub btnRestore_Click(ByVal sender As Object, ByVal e As EventArgs)
    RadPersistenceManager1.LoadState()
    RadGrid1.Rebind()
End Sub

Notes

• Using this approach you can implement a feature that could store/restore any settings of the DetailTables and not only the expanded items.
• To make the save and restore state automatic, you can call the SaveState() and LoadState() methods in any event that triggers automatically. For instance, the Page Life-Cycle Events trigger every time the page loads, even on PostBacks.