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SAP_CAP_Cheatsheet.md

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Table of Contents

CDS

General Knowledge

package.json is where metadata for the cds application is stored, e.g. the persistent database where to load the data from The foreign key for a to-one association is generally <entity_name>_ID (e.g. In table books author_ID pointing to the author) but for code lists it is <entity_name>_code (e.g. In table orders country_code pointing to the country)

Naming conventions

These will make cds watch automatically set up the db and services

  • db/ folder: schema.cds file with the domain modeling (entities, associations, etc)
  • data/ or csv folder: where the csv files have the format <namespace-table>.csv (e.g. sap.capire.bookshop-Books.csv or sap-capire-bookshop-Books.csv)
  • srv/ folder: implementation of services with the same name as the cds file (e.g. cat-service.cds and cat-service.js)
  • app/ folder: where the web apps are stored. If there is an index.html file in it cds watch will use this as the default page

Referencing other models

Names starting at ./ or ../ are resolved relative to the current model
If the reference is a directory, it is loaded from a .../index.<json|cds> file in that directory (... means to look recursively in that directory)
Others are absolute references, prefixed with @, look under the node_modules folder for that path (?)

Useful commands

cds watch - starts and keeps track of changes in the application
cds deploy --to <db_type:custom_db_name> - deploys the models to a persistent database (sqlite, hana, etc)
cds compile <cds_file_path> --to sql - to create the Tables/Views needed to represent the models in that file and see the sql commands in the console cds env ls to inspect all the project's specific configurations npm install --save <package> adds that package as a dependency in package.json so that it is installed when deploying to the cloud

Useful APIs

db_transaction = srv.transaction(req) - starts or joins a transaction on the db (rolls back if errors occur) db_transaction.run(<query>) - runs the query on the database

OData

OData queries support expansions through a foreign key, for instance <URL>/catalog/Authors?$expand=books($select=ID,title) to show the authors with their respective books

External Services

cds import <path_to_edmx_file to import an external service, a folder external will be created with both the imported file and a cds model definition (.csn file) to be used by the application. A requirement is added in the package.json to the external application

Deploying to the cloud

Not being able to use cf was solved in by adding an env variable

  • cf login to login to the cloud foundry account and space
  • cds add hana --force to update package.json with the requirement to use hana as the data source
  • cds build/all to build the application
  • cf create-service <type_of_service>(look up in cf marketplace, probably hana) <service_plan> (hdi-shared) <service_name> (in gen/db/src/manifest.yaml under services)
  • cf push -f gen/db/ to push the data (tables, views, etc) into the cloud
  • cf push -f gen/srv/ --random-route (creates a new url every time it is deployed) to push the actual service - the generated url is shown in the console under routes

For multitarget applications

As an alternative to the built-in method above, this way the application is deployed as a whole - less manual steps, so easier to automate for production
The project should be stored locally, while storing it in OneDrive problems arose during the build probably due to failed syncs

  • cf install-plugin multiapps to be able to use the deploy command
  • cds add mta generates an mta.yaml with various modules (Cloud Foundry Apps) and resources (Cloud Foundry Spaces)
  • mbt build -t ./ to build the application archive (builds each module in mta.yaml)
  • cf deploy <archive-path> (mtar file)
  • cf logs <service-name> to see what is going on with a given service
  • cf services shows the services and associated apps running for the logged in space

Authentication and Authorization

cds add xsuaa --for production adds xsuaa service to package.json and creates the xsuaa security configuration for the project cds compile srv/ --to xsuaa > xs-security.json updates package.json with a requirement for uaa
path: xs-security.json should be added to the mta.yaml under resources

UI

UIs can be built through freestyle SAPUI5 applications or using SAP Fiori elements applications.
The latter is based on SAPUI5, but provides a series of out-of-the-box elements for most common usecases
A launchpage.html file can have all the web apps centralized and shown in a local SAP launchpad
The name of your SAP Cloud service (cpapp in this case) should be unique within an SAP BTP region (?)