A CAP plugin that structures handlers as one file per entity, in a folder per service, instead of one service implementation that keeps growing.
Answers the outcome for data that is not the project's own entities: a services folder holds a class per external service, and the requests to an external API or another database are written there rather than in the handler.
The project's own entities are not covered by that layer. What the README states is where the external-service classes go; the calls inside them are the application's.
Where a class goes is the declaration: a folder per service under src/handlers, and inside it a class per entity named after that entity. As a cds-plugin it loads itself, so the service implementation holds nothing that lists the classes.
The folder and file names carry the binding, so renaming a service or an entity in the model means moving or renaming files. The README read today does not state which method names a handler class uses.
How an application is arranged once written in TypeScript
npm add cds-plugin-handlersDerived from the package name. No recipe recorded; the README has the configuration.
CAP CDS Plugin that enables classes for entities in a structured way + implementing an additional layer for service classes to separate the implementation for requests to external api's.
npm install cds-plugin-handlersCreate a folder "handlers" in the "src" folder. Inside the "handlers" folder you have to create a folder for each service, e.g.: "CatalogService" for the service CatalogService. In here, you have to create a handler class for each entity, e.g.: "BooksHandler" for the entity Books.
This plugin also allows you to implement separation by concerns when it comes to external services. All requests to external services or even to different databases can be stored in a folder "services". In here, you have to create a service class for each external service to implement all the needed requests.
The folder structure in the "srv" folder should look like this:
srv
├── src
│ └── handlers
| | ├── CatalogService
| | | ├── BooksHandler.ts
│ | | └── AnyOtherHandlerY.ts
│ | └── AnyOtherService
│ | └── AnyOtherHandlerX.ts
| └── services
│ ├── BookService.ts
│ └── AnyOtherServiceX.ts
└── cat-service.cdsWe have documented this approach already before the plugin but the documentation still applies, only the setup changed. Everthing is explained in the following blog posts:
Demo app available on GitHub https://github.com/lemaiwo/cds-plugin-handlers/tree/main/sample
Demo project using services: https://github.com/lemaiwo/ReCAPBTPServiceOverview
Sources are graph entities: the same page may back several entries, and an unreachable source flags every row that rests on it.
artifact:lemaiwo-cds-plugin-handlers