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Dragolea
Explorer
Hi all,

Many of us are leveraging SAP CAP (Node.js with TypeScript) for our projects.

While CAP provides an abstract mechanism to derive RESTful oData services given a CDS data model there's always room for more efficiency and improvement in the implementing communication between business logic, service, and persistence layer.

It shall be noted at this point, that improvements have been attempted with regard to the service layer communication using cds-routing-handler However, this framework does not appear to be maintained, especially for newer versions of CAP.

-


We introduce two powerful npm packages developed by the ABS & DxFrontier team:  

In this blog, we will concentrate on the CDS-TS-Repository.

Prerequisites


Before we dive in, you should have a basic understanding of SAP CAP NodeJS and TypeScript. If you need a refresher, here are some helpful resources Official SAP CAP TypeScript

Section 1: Introduction to CDS-TS-Repository


The goal of CDS-TS-Repository - BaseRepository is to significantly reduce the boilerplate code required to implement data access layers for persistence entities by providing out-of-the-box actions on the database.

Section 2: Benefits of CDS-TS-Repository



  • Common actions for the most used persistence actions to the DB :

    • create - Create a new entry in the DB.

    • createMany - Create many entries in the DB.

    • update - Update entry in the DB.

    • delete - Delete an entry from the DB.

    • exists - Check the existence of an entry in the DB.

    • find - Find entries in the DB.

    • findOne - Find one entry in the DB.

    • ... and many more



  • Support draft actions by using BaseRepositoryDraft class and Mixin.


Section 3: Getting Started with CDS-TS-Repository


Now, let's get started with CDS-TS-Repository. We'll walk you through the steps to integrate it into your SAP CAP TypeScript project, providing code snippets and configuration examples for a smooth onboarding.

1: Install cds-ts-repository NPM package.
npm install @dxfrontier/cds-ts-respository

 

2. Generate type entities using cds-typer
npx @cap-js/cds-typer "*" --outputDirectory ./srv/util/types/entities

The cds-typer offers a way to derive TypeScript definitions from a CDS model to give you enhanced code completion and a certain degree of type safety when implementing services.

  • Target folder :./srv/util/types/entities - Change to your location destination folder.


 

3: MyRepository class

Start by creating a MyRepository class, which will extend the BaseRepository to handle operations for your entity.
import { BaseRepository } from '@dxfrontier/cds-ts-repository';
import { MyEntity } from 'YOUR_CDS_TYPER_ENTITIES_LOCATION';

class MyRepository extends BaseRepository<MyEntity> {
constructor() {
super(MyEntity) // a CDS Typer entity type
}

aMethod() {

// BaseRepository predefined methods using 'MyEntity' entity
// All methods parameters will allow only keys/values of type MyEntity

const result1 = await this.create(...)
const result2 = await this.createMany(...)
const result5 = await this.getAll()
const result6 = await this.getAllAndLimit(...)
const result7 = await this.find(...)
const result8 = await this.findOne(...)
const result9 = await this.delete(...)
const result10 = await this.update(...)
const result11 = await this.updateLocaleTexts(...)
const result12 = await this.exists(...)
const result13 = await this.count()
const results14 = await this.getLocaleTexts()
const results15 = await this.builder().find(...).orderAsc([...]).getExpand(['...']).execute()
// ...

}
}

 

Section 4: Examples


Let's see how CDS-TS-Repository simplifies common tasks.
import { BaseRepository } from '@dxfrontier/cds-ts-repository';
import { MyEntity } from 'YOUR_CDS_TYPER_ENTITIES_LOCATION';

class MyRepository extends BaseRepository<MyEntity> {
constructor() {
super(MyEntity);
}

public async aMethod() {

const created = await this.create({
name : 'a new entry',
description : 'description'
})

// update
const keys = { ID : '34' }
const fieldsToUpdate = { name : 'updated entry with a new name' }

// updated will return boolean (true if updated, false otherwise)
const updated = await this.update(keys, fieldsToUpdate)

// exists will return boolean (true if exists, false otherwise)
const exists = await this.exists({ID : '84c67833-a9cb-450c-ae02-a32c3a7a6f6b'})

// results will contain an Array of your entity object
const results = await this.getAll();

// delete will contain true if delete operation is successfull, and false otherwise
const deleted1 = await this.delete({ name: 'Customer' });
const deleted2 = await this.delete({ ID: '2f12d711-b09e-4b57-b035-2cbd0a02ba19' });

// count the number of items
const itemsLength = await this.count();

}

 

Section 5: Draft compatible using BaseRepositoryDraft and Mixin


BaseRepositoryDraft repository provides a clear separation of methods for working with active entities and draft instances.
import { BaseRepository, BaseRepositoryDraft, Mixin} from '@dxfrontier/cds-ts-repository'
import { MyEntity } from 'YOUR_CDS_TYPER_ENTITIES_LOCATION'

class MyRepository extends Mixin(BaseRepository<MyEntity>, BaseRepositoryDraft<MyEntity>) {
constructor() {
super(MyEntity)
}
// ... define custom CDS-QL actions if BaseRepository ones are not satisfying your needs !
}

 

Use BaseRepository methods when dealing with active entity instances.

  • updatedeletecreatecreateMany...


Use BaseRepositoryDraft methods when working with draft entity instances.

  • updateDraftdeleteDraftfindOneDraftfindDrafts...


 


Mixin BaseRepository and BaseRepositoryDraft


 

For more info about CDS-TS-Repository visit the following GitHub

Conclusion


In conclusion, CDS-TS-Dispatcher combined with CDS-TS-Repository is a powerful tool that can speed up your SAP CAP TypeScript projects by eliminating repetitive code and being a better fit for common team architecture setups.

Whether you're starting a new project or enhancing an existing one, integrating CDS-TS-Repository is a significant step towards a more efficient and productive development journey.

Additional Resources


Find an example of usage of the CDS-TS-Samples GitHub

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