paginator with Gentaick

paginator.ts

import { Expose } from "class-transformer";
import { SelectQueryBuilder } from "typeorm";

export interface PaginateOptions {
  limit: number;
  currentPage: number;
  total?: boolean;
}

export class PaginationResult<T> {
  constructor(partial: Partial<PaginationResult<T>>) {
    Object.assign(this, partial);
  }

  @Expose()
  first: number;
  @Expose()
  last: number;
  @Expose()
  limit: number;
  @Expose()
  total?: number;
  @Expose()
  data: T[];
}

export async function paginate<T>(
  qb: SelectQueryBuilder<T>,
  options: PaginateOptions = {
    limit: 10,
    currentPage: 1
  }
): Promise<PaginationResult<T>> {
  const offset = (options.currentPage - 1) * options.limit;
  const data = await qb.limit(options.limit)
    .offset(offset).getMany();

  return new PaginationResult({
    first: offset + 1,
    last: offset + data.length,
    limit: options.limit,
    total: options.total ? await qb.getCount() : null,
    data
  })
}

how to used it
public async getEventsOrganizedByUserIdPaginated( userId: number, paginateOptions: PaginateOptions ): Promise<PaginatedEvents> { return await paginate<Event>( this.getEventsOrganizedByUserIdQuery(userId), paginateOptions ); }