@phanid79 thanks for the detail this helps.
Modular approach
So first up, building reusable data objects to be reused by different applications. I have seen this used with great effect using a modular approach - in this case Application B is built on Application A and can directly reuse the data object as defined in app definition. I have seen this implemented in both Traditional and Constellation Apps, so there is no problems here - it leans into how Pega OOTB App Definition and Inheritance work.
Your issue
Assuming you don’t have the opportunity to restructure your apps, then we should treat A and B as separate, with B pulling records from A as if it was another non-Pega SOR. After reading your outline, i’m thinking perhaps in App B the setup is not quite right. You should be creating a data object in App B using the native Pega Wizard and referring to the services you have for both a List and Single Page in App A.
- This creates a concrete data object in App B, with the right datapages so it can then be sourced as a Data Reference.
This is where I believe you might be getting stuck, a Data Reference would only be available to you if you had both single and list pages for the object (this is a new concept in Constellation that wasn’t required in UI Kit).
- Although it is not 100% your scenario, this Constellation 101 might point you in the right direction for setup?
- Managing external system of record through REST with CRUD actions in Pega Constellation | Support Center
- You can see under “1. Prerequisites - Data object and REST API as data source” there is discussion about the datapages needs on an object - though he goes on to talk about updating the saveable one so they can allow App B to change records in App A.
- Managing external system of record through REST with CRUD actions in Pega Constellation | Support Center
If you need step by step help, I would suggest raising a ticket to Pega Support. As they can step through your local configuration and help pick up where you might be going wrong. Though it looks like you are close!
Do let us know how you get on, help share the solution for future people who get stuck here.