feat: enhance .drafts properties with draft table properties

[stockbal]

Hi @daogrady,

this is a proposal for enhancing the type behind the .drafts property of draft enabled classes, to include the additional fields that will be generated for draft tables.

At the same time it would also overwork .drafts at the plural entity, to use an enhanced version of the generated plural class of an entity, so fixes #163.

P.S.: tests do not yet exist. I will create them if you think we can go ahead with this approach

Tasks

• add test cases

Sample

// cat-service.cds
service CatalogService {
  @odata.draft.enabled
  entity Books : cuid { }
}

Generated classes

// /_/index.ts
export type DraftEntity<T> = T & {
    IsActiveEntity?: boolean | null
    HasActiveEntity?: boolean | null
    HasDraftEntity?: boolean | null
    DraftAdministrativeData_DraftUUID?: string | null
}
export type DraftOf<T> = { new(...args: any[]): DraftEntity<T> }
export type DraftsOf<T> = typeof Array<DraftEntity<T>>

// /CatalogService/index.ts
export class Book extends _BookAspect(__.Entity) {static drafts: __.DraftOf<Book>}
export class Books extends Array<Book> {static drafts: __.DraftsOf<Book>}

Explanation about types

The type DraftEntity<T> is exported so users can type their variables or parameters to a draft entity

import { Book } from "#cds-models/CatalogService";
import { DraftEntity } from "#cds-models/_";

function getBookDraft(): DraftEntity<Book> {}

Side note

Fixes auto-closed issue #100

[daogrady]

Looks good, thanks for yet another cool contribution! 🙂