TreeViewPicker control is like lookupPicker control but shows the data in at tree view way.
The settings that should be declared are the Lookup Details (list, displayName, value etc.) and one property in the Extra Configuration tab: ParentFieldName.
The ParentFieldName should be located in the list that is already declared in Lookup Details and it should be lookup field that is self-referenced.In Extra Configuration field should be declared the internal name of the field.(in our example below ParentFieldName=ParentCategory)
There is an example below:
Our TreeViewPicker Control contains these data:
We are reading our data from a list with 2 fields, Category and ParentCategory where Category is a single line text and ParentCategory is a lookup field that looks in Category field within the same list.