list report search on composite entity

[roman_schneider]

I have two CDS entities A and B. B is an composition and has an Attribute BNAME.

In a list report-app  i want to filter the result of A by BNAME (All A which have a certain BNAME) and then the rest should be as usual: Navigate to ObjectPage of A and display and edit. 

The challenge is to get the filter attribute into entity A and the content of BNAME into a result column  to be style guide conform.

STRING_AGG could have been an option, but ist not supported in my HANA 2022-System.

How do you archieve such a search over compositions ?  

[saurabh__khare38]

We are on S42022 FPS02 and were able to implement STRING_AGG on AMDP using CDS table function or you could try using virtual element on CDS for getting BNAME to A instead of STRING_AGG

[roman_schneider]

The disadvantages of unmanaged behaviour are too great.  We have the search pattern in several places.

[roman_schneider]

Thanks for the idea. But i lose the extensibility and the possibility of a behaviour definition on entity A

[saurabh__khare38]

You can still have the behaviour definition just that it would be an unmanaged one

SAP ABAP RAP : Custom Entities with compositions relationship in a Fiori Elements App

[roman_schneider]

STRING_AGG would only solve part of the challenge anyway.

as far as i can see, the problem has two parts:

1. A field ist needed to Filter against.     Tried a _B.BNAME as FILTER in der View, but this will change cardinality and the navigation to the object page went wrong.   A SELECT DISTINCT does not change it
2. A Result Column is needed to show the entity data. Do I have to display all BNAMEs for an A to be style guide conform or is the appropriate filter attribute sufficient? 

Any ideas? 

[saurabh__khare38]

With BNAME added to A, the cardinality is bound to change and for the filter to work out of the box for BNAME it has to be added to A. I would suggest going for a custom entity in this case where you can handle the filter in your code. You would need a dummy field called BNAME in A. The value entered in the filter would be available in the implementation of the custom entity and can be used to filter B first and then select A based on that before populating the result.

Custom Entity