Save Group Expand/Collapse State

[Nick Wood]

Hi There, I know that this has been asked several times, such as here:
http://www.telerik.com/community/forums/silverlight/gridview/rebinding-updating-while-maintaining-selection-position-expansion.aspx

But I want to get clarify what I am trying to do. My situation is that I cannot update the items in the itemssource, I have to rebind as I am binding to a view but updating from the entity item. It obviously requires a refresh of the view results and therefore a rebind.

I need to preserve the grid grouping expand/collapse state so that after the rebind the user sees the same grid layout.

Any help please.

[Dimitrina]

Hello,

 Please check this demo for Persistence Framework on how to save/load settings:
http://demos.telerik.com/silverlight/#PersistenceFramework/GridViewCustomSerialization 

Regards,
Didie
the Telerik team

[Mike Shilkov]

Hello Didie,

Your post doesn't seem to be a full reply to initial question.
What Nick needed (and I need) was to save the expand/collapse state of all groups after Rebind operation. 
The example that you mentioned shows how to save the grouping itself, not the expand/collapse state. I had a try: groupped by Country, expanded Agrentina, Saved, then expanded Canada and clicked Load; nothing happened, the expand/collapse state was not restored.
Do you have a working sample of what we need? Or do I have to write it myself with getting the current state of grid and then re-applying it after rebind?

Thanks

[Dimitrina]

Hello,

In regard to your question, I would recommend you to check this forum thread where a sample project is attached.

I hope this is what you need.

Greetings,
Didie
the Telerik team

[Serguei]

Here is my solution:

        private struct GroupNameHeader
        {
            public string GroupName;
            public string GroupHeader;
            public string ParentGroupHeader;
        }
 
        private List<GroupNameHeader> _expandedGroups;
 
        protected void SaveExpandedGroups()
        {
            _expandedGroups.Clear();
            SaveExpandedGroups(Grid.Groups);
        }
 
        protected void RestoreExpandedGroups()
        {
            RestoreExpandedGroups(Grid.Groups);
        }
 
        private void SaveExpandedGroups(DataGroupCollection Groups)
        {
            foreach (DataGroup group in Groups)
            {
                if (group.IsExpanded)
                {
                    GroupNameHeader expandedGroup;
                    expandedGroup.GroupName = group.GroupDescriptor.GroupNames[0].PropertyName;
                    expandedGroup.GroupHeader = group.Header;
                    if (group.Parent == null)
                    {
                        expandedGroup.ParentGroupHeader = null;
                    }
                    else
                    {
                        expandedGroup.ParentGroupHeader = group.Parent.Header;
                    }
                    _expandedGroups.Add(expandedGroup);
                    SaveExpandedGroups(group.Groups);
                }
            }
        }
 
        private void RestoreExpandedGroups(DataGroupCollection Groups)
        {
            if (_expandedGroups.Count > 0)
            {
                foreach (DataGroup group in Groups)
                {
                    foreach (GroupNameHeader expandedGroup in _expandedGroups)
                    {
                        string parentGroupHeader = null;
                        if (group.Parent != null)
                        {
                            parentGroupHeader = group.Parent.Header;
                        }
                        if (group.GroupDescriptor.GroupNames[0].PropertyName == expandedGroup.GroupName &&
                            group.Header == expandedGroup.GroupHeader &&
                            parentGroupHeader == expandedGroup.ParentGroupHeader)
                        {
                            group.Expand();
                        }
                    }
                    RestoreExpandedGroups(group.Groups);
                }
            }
        }

You can use SaveExpandedGroups() before bind and RestoreExpandedGroups() after.

Serguei

[Dimitrina]

Hello,

Thank you for sharing your solution with the community. As an additional note I would like to mention that you could also save the keys for the Groups and not the entire groups.

Regards,
Didie
Telerik

[Serguei]

Hello Didie,
I am actually saving keys represented by

        private struct GroupNameHeader
        {
            public string GroupName;
            public string GroupHeader;
            public string ParentGroupHeader;
        }

and not the entire groups.

Cheers,
Serguei