How to cascading drop down list questions in App Portal

[#1]

Summary

This article will provide with some help to configure cascading drop down list questions in App Portal

Synopsis

The scenario case is to set up:

• Question26 where the dropdown list is populated from a web service call WS1
• Question27 where the dropdown list is populated from a web service call WS2 that takes the answer to Question26 as an input parameter

The difficulty is by default the parameter is always passed through with the literal value ?##QuestionID:26##? rather than the answer to the question.
How to let the system to pass the answer to Question26 through to the web service call to populate the Question27 dropdown list.

Discussion

To achieve above configuration, You would like to need to specify the ?Reload answers for questions? setting under web site->catalog behavior.
The value should be ?26~27?. This indicates that the when the source question of 26 changes, then the target question 27 should reload.. This should cause the variable to be resolved. As screenshot shown below.