Using base, interface and consumption view for a entity

[felixw]

Dear community,

I was wondering about the sense of base views in an RAP context: Most of the documentation and tutorials I read claim that in RAP a single entity should be composed out of three CDS view layers: (1) base view, (2) interface view and (3) consumption view. This is also reflected in the showcase app.

However, from my experiences so far with RAP I find all three layers rather cumbersome. If one layer is skipped I think the base layer is the obvious choice. Entities consisting out of interface view and consumption view only can be seen for example in the DMO flight scenario.

I was wondering what are the experiences of others. Do you use all three layers or only two? What are your experiences there?

Kind regards

[DiegoValdivia]

SAP will not like my answer, but in my case, I don't use the three layers, but only use one.

When I started developing my firsts production apps, I tried to follow the three layer technique, but I found it to be very time consuming. I mean, every time a user wanted to add a new field or wanted to remove a new field, I had to add it to the three layers, including the Behavior Definition and Behavior Projection as well as the Behavior Pool Class.

The biggest problem came when deleting fields, because I got a lot of dependency errors that took a lot of time to fix.

After two years working on ABAP Restful apps, I think that the three layer technique is good if you plan to re-use the base objects, but if you plan to use the main CDS view only in one app, I don't think it's necessary.

But again, this is just my experience, I wouldn't say it's an advice.

[felixw]

Thanks for sharing your experiences @DiegoValdivia. After a year with RAP I have basically the same experiences with using three layers. And I couldn’t agree more that especially removing fields or changing field names is rather painful (e.g. fixing a typo which is in all three layers can take up to an hour).

To me, regarding to your mentioned re-usage aspect it is also questionable how often intense re-usages of custom developed views actually happens. Of course, for central SAP standard  views the re-usage should happen quite frequently.

I just re-factored an application to use two layers instead of three which so far seems like a good decision.