Asymmetrik/node-rest-starter

import config from 'config';
import { HydratedDocument, Query, Schema } from 'mongoose';

const MONGO_TIMEOUT_ERROR_CODE = 50;

export interface PagingResults<DocType> {
    pageNumber: number;
    pageSize: number;
    totalPages: number;
    totalSize: number;
    elements: DocType[];
}

export interface Paginateable<DocType> {
    paginate(
        pageSize: number,
        pageNumber: number,
        runCount?: boolean,
        countTimeout?: number
    ): Promise<PagingResults<DocType>>;
}

export function paginatePlugin<EnforcedDocType, TModelType, TInstanceMethods>(
    schema: Schema<EnforcedDocType, TModelType, TInstanceMethods>
) {
    schema.query['paginate'] = async function <DocType>(
        this: Query<HydratedDocument<DocType>[], DocType>,
        pageSize: number,
        pageNumber: number,
        runCount = true,
        countTimeout = config.get<number>('maxCountTimeMS')
    ): Promise<PagingResults<DocType>> {
        const countPromise = runCount
            ? this.model
                    .find(this.getFilter())
                    .maxTimeMS(countTimeout)
                    .countDocuments()
                    .exec()
                    .catch((err) => {
                        // Hit timeout
                        if (err.code === MONGO_TIMEOUT_ERROR_CODE) {
                            return Promise.resolve(Number.MAX_SAFE_INTEGER);
                        }
                        return err;
                    })
            : Promise.resolve(Number.MAX_SAFE_INTEGER);

        const resultsPromise = this.skip(pageNumber * pageSize)
            .limit(pageSize)
            .maxTimeMS(config.get<number>('maxTimeMS'))
            .exec();

        const [totalSize, elements] = await Promise.all([
            countPromise,
            resultsPromise
        ]);
        if (totalSize === 0) {
            pageNumber = 0;
        }
        return {
            pageSize,
            pageNumber,
            totalSize,
            totalPages: Math.ceil(totalSize / pageSize),
            elements
        };
    };
}