Change Tracking - Agrejus/pouchdb-entity-fabric GitHub Wiki

import { DataContext, IDbRecord, IDbRecordBase } from "pouchdb-entity-fabric";

export enum DocumentTypes {
    Notes = "Notes",
    Books = "Books"
}

export type OnChangeHandlers = {
    [DocumentTypes.Books]: { [key: string]: (data: IBook[]) => void },
    [DocumentTypes.Notes]: { [key: string]: (data: INote[]) => void }
}

const onChangeHandlers: OnChangeHandlers = {
    [DocumentTypes.Books]: {},
    [DocumentTypes.Notes]: {}
};

export interface IBook extends IDbRecord<DocumentTypes.Books> {
    name: string;
    author: string
}

export interface INote extends IDbRecord<DocumentTypes.Notes> {
    message: string;
}

export class YourDataContext extends DataContext<DocumentTypes> {

    constructor() {
        super('test-v1');
    }

    private _types = {
        map: {} as typeof this.books.types.map & typeof this.notes.types.map
    }

    onChange<TDocumentType extends keyof typeof this._types.map, TEntity extends typeof this._types.map[TDocumentType]>(documentType: TDocumentType, callback: (data: TEntity[]) => void) {
        const id = "d";
        onChangeHandlers[documentType][id] = callback as () => void;

        return () => {
            delete onChangeHandlers[documentType][id];
        }
    }

    protected override async onAfterSaveChanges(getChanges: () => { adds: IDbRecordBase[]; removes: IDbRecordBase[]; updates: IDbRecordBase[]; }) {
        const { removes, adds, updates } = getChanges();
        const all = [...removes, ...adds, ...updates];

        for (const documentType in onChangeHandlers) {
            const handlers = Object.values(onChangeHandlers[documentType] as { [key: string]: (data: any[]) => void })
            const data = all.filter(w => w.DocumentType === documentType);

            if (data.length > 0) {
                for (const handler of handlers) {
                    handler(data);
                }
            }
        }

    }

    notes = this.dbset().default<INote>(DocumentTypes.Notes)
        .keys(w => w.auto())
        .create();

    books = this.dbset().default<IBook>(DocumentTypes.Books)
        .keys(w => w.auto())
        .create();
}