feat: PoC for dynamic constraints using standard cds views

[danjoa]

Experimental Dynamic Constraints

This example demonstrates how to use dynamic constraints in a CAP application. It includes a service definition and a test setup to validate the constraints.

Prerequisites

You've setup the cap/samples like so:

git clone -q https://github.com/sap-samples/cloud-cap-samples cap/samples
cd cap/samples
npm install

Testing

Test like that in cds.repl from cap/samples root:

cds repl --run bookshop/test/dynamic-constraints

await AdminService.create ('Books', { title:'   ', author_ID:150 })

See also: bookshop/test/dynamic-constraints/readme.md

[danjoa]

The recent commit adds ...

• constraints views on service entities level
• base association to refer to data excluded from service entities (here Authors:books) from within constraints
• automatic validations after each 'CREATE' → would be before COMMIT later.

[danjoa]

Recent commit 65eccfa moved all experiments into a dedicated folder so we could merge to main w/o damage.