Hello Experts,
I have been seeing RAP since 2020 and unfortunately the path for RAP / OData version is not clear to me. What is the best practice / recommendation to use OData V2 or V4 ?
Some cases works better in OData V4 and some works better in OData V2.
There is a blog post ( Is it time to switch to OData v4? ) in 2021. But the answer is to worth investigating in V4 and not a recommendation. Hence I would like to get to know from community on latest feedback to use V2 or V4.
Few inconsistencies :
- For OData V4 UI the create button is only visible if draft is enabled in Behavior definition.( question - Question - Cannot see Edit and Delete Button for Managed scenario in ABAP Restful Programming Model (RAP) ) ( V2 is better ).

- Attachments handling is different in OData v2 and V4 ( see here - questions/feedback )( V4 is better ).
- Enabling / Disabling button is better in OData V2 but OData V4 is consuming the space unnecessarily on the screen for disabled buttons and there is no option available to hide action in RAP behavior implementation.( V2 is better ).

Update from "SAP Fiori elements and SAP Fiori tools roundtable call":
- The answer cannot be simply generalized to say V2 or V4. V2 is a stable version and V4 has more features.
- The behavior in ADT Preview is not guaranteed and the application must be deployed into actual fiori application and behavior to be checked. If needed, Fiori elements annotations to be used along with ABAP/RAP CDS annotations.
- OData V4 best supports for Draft applications compared to Non-Draft application CRUD operations.
Best wishes,
Ramjee Korada.