VBCS : ExpandAll , Mark All, Read All data of EDITABLE treetable issue

Summary

VBCS : ExpandAll , Mark All, Read All data of EDITABLE treetable issue

Content

I have created a EDITABLE treeTable based on the below link.
https://www.oracle.com/webfolder/technetwork/jet/jetCookbook.html?component=rowExpander&demo=tableCollectionRowExpander

Here I am not able to do below actions. Please help on this by sharing a sample VBCS application with the below functionalities.

1. Read all the data on some button action. Example: On click of Save, I need to read all the rows with newly entered/updated data and save it to DB.
2. By default, the TreeTable has to be in ALL expanded state. Expand ALL option for this TreeTable based on Collections.