Getting Started

This project extends the example cds bookshop project, available here: https://cap.cloud.sap/docs/get-started/

It demonstrates how to to use only persistence layer generated by CAP, not exposing the Resful services for the persisted entities. In this example we extend cat-service.js with custom code that inserts and persists Logs in the DB during GET for the Books. Logs entity and persistence layer is generated by CAP, but no exposure of REST-services is done for the Logs.

File or Folder	Purpose
app/	content for UI frontends goes here
db/	your domain models and data go here
srv/	your service models and code go here
package.json	project metadata and configuration
readme.md	this getting started guide

Next steps

• Run npm run build to transpile Log.ts file into javascript
• Open a new terminal and run cds watch
• (in VS Code simply choose Terminal > Run Task > cds watch)
• Start adding content, for example, a db/schema.cds.

Custom Bootstraping of CDS application with Express

In order to bootstrap CDS within existing Express application (not having to start the app with cds watch), we prepared a file app.js, that contains all needed code to bootstrap CDS with express.
This uses cds-bootstrap.js, which contains all needed bootstrap code, as also documented in: https://cap.cloud.sap/docs/node.js/cds-server

Running the app

node .\app.js to boostrap the application with Express.

Testing

1. Test that custom express rest-services are working, opening url: http://localhost:4004/logs - it should return logs from DB
2. Test that CDS-REST-Services are working fine by typing http://localhost:4004/catalog/Books?$top=11 - it should return content of Books entity in DB
3. You can open postman collection from and run POST to create a logs and GET to get those logs to see that the Express endpoints are working postman collection

Custom REST services with CAP-persistence

Custom REST services are implemented in the file cat-service
There is a Express REST GET endpoint /logs that reads the Log entity from DB.
There is a Express REST POST endpoint to /logs that writes the Log entity in DB.

Endpoint	REST Method	Sample payload	Comment
/logs	POST	{'tenantID':'testTenant', 'level':'D'}	Adds a log to the logs table with CDS persistence
/logs	GET	-	gets logs using CDS persistence
/catalog/Books?$top=11	GET	-	consumes CDS OData REST service

Please note that the /logs endpoint is not registered as service within CDS service catalog cat-service.cds, it's just a simple Express endpoint

Testing DB log population using CAP-generated code

1. open http://localhost:4004/catalog/Books
2. The request above will add logs to the Log entity in the DB (see GET code handler in cat-service.js )
3. To test, if log entries have been added, go to DB and type : sqlite3' .open db/my-bookshop.db select * from my_bookshop_Logs`
4. Alternatively you can open cat-service.cds and temporarily stwitch on exposure for Logs entity by adding this line:
   entity Logs @readonly as projection on bookshop.Logs;
   Then, opening the Logs you should see newly added logs by calling this endpoint: http://localhost:4004/catalog/Logs

Learn More

Learn more at https://cap.cloud.sap/docs/get-started/.