@conpago/mongo-cursor-pagination/src/findWithReq.ts

Make it easy to return cursor-paginated results from a Mongo collection

import { Collection } from "mongodb";
import find from "./find";
import sanitizeQuery from "./utils/sanitizeQuery";
import { QueryParams, PaginationResponse } from "./types";

/**
 * A wrapper around `find()` that make it easy to implement a basic HTTP API using Express. So your
 * user can call "/list?limit=1&fields=_id,name" and the querystring parameters will be passed
 * to this method on the Express request object.
 *
 * @param {ExpressRequest} req An express request object with the following on the querystring:
 *    -limit: If a numeric string, passed to `find()` as the limit. If limit also passed in params
 *      then this value cannot exceed it.
 *    -next: If a non-empty string, passed to `find()` as the next cursor.
 *    -previous: If a non-empty string, passed to `find()` as the previous cursor.
 *    -fields: If a non-empty string, used to limit fields that are returned. Multiple fields
 *      can be specified as a comma-delimited list. If field name used is not in params.fields,
 *      it will be ignored.
 * @param {MongoCollection} collection A collection object returned from the MongoDB library's.
 * @param {Object} params See documentation for `find()`, plus these options:
 *    -overrideFields: an object containing fields that should override fields from the querystring, e.g.
 *      {_id: 0} or {internalField: 1}. We only support field exclusion for _id, as we expect whitelists
 *      for fields from both params.fields and params.overrideFields.
 */
export default (
  req: { query: any },
  collection: Collection | any,
  params: QueryParams
): Promise<PaginationResponse> => {
  params = sanitizeQuery(req.query, params);

  return find(collection, params);
};