Expression based on Parent child relationship for Stacked bar chart

[Jothi]

I have a Filter for "Child" on my sheet.

I have 2 charts - one that displays data for the "Child" selected in the filter

I have another stacked bar chart that brings bars, the bars should be the name of all the "Child" whose "Parent" is the value selected in the Child Filter. Below is my sample data model - 

Child	Parent
Castle – Business Unit	NULL
Castle Media	Castle – Business Unit
Castle Solutions	Castle – Business Unit
Castle Teleservices	Castle – Business Unit
Castle Group	Castle – Business Unit
Group Finance	Castle Group
Group Human Resources	Castle Group
Group Regulatory Affairs	Castle Group
Technology, Strategy & Development	Castle Group
Treasury & Debt Execution	Castle Group

I want to write an expression that would select the stacks of the bar chart such that,

Bar expression = All Child, where parent = (child selected in the filter)

I am totally new to qlik sense, there might be a straight forward way for this, may be I just dont know it yet. 

[hic]

You can do this if you create an ancestor table in the load script, using HierarchyBelongsTo.
See https://help.qlik.com/en-US/qlikview/May2021/Subsystems/Client/Content/QV_QlikView/Scripting/ScriptP...

Suggested reading:
https://community.qlik.com/t5/Qlik-Design-Blog/Unbalanced-n-level-hierarchies/ba-p/1474325
https://community.qlik.com/t5/QlikView-Documents/Hierarchies/ta-p/1487801

[MarcoWedel]

Although I agree that creating a hierarchy in this case should be the preferred solution, I just wanted to add that in case you are looking for a solution that only uses direct descendants (i.e. across 1 level), then using a set expression like

{$<Child=, Parent=p(Child)>} 

or

{$<Child=, Parent=$::Child>} 

might be enough.

hope this helps

Marco