@tepez/mongo-cursor-pagination/dist/node/search.js

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

function _asyncToGenerator(fn) { return function () { var gen = fn.apply(this, arguments); return new Promise(function (resolve, reject) { function step(key, arg) { try { var info = gen[key](arg); var value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then(function (value) { step("next", value); }, function (err) { step("throw", err); }); } } return step("next"); }); }; }

const _ = require('underscore');

const config = require('./config');
const bsonUrlEncoding = require('./utils/bsonUrlEncoding');

/**
 * Performs a search query on a Mongo collection and pages the results. This is different from
 * find() in that the results are ordered by their relevancy, and as such, it does not take
 * a paginatedField parameter. Note that this is less performant than find() because it must
 * perform the full search on each call to this function.
 *
 * @param {MongoCollection} collection A collection object returned from the MongoDB library's. This MUST have a Mongo
 *    $text index on it.
 *    See https://docs.mongodb.com/manual/core/index-text/.
 * @param {String} searchString String to search on.
 * @param {Object} params
 *    -query {Object} The find query.
 *    -limit {Number} The page size. Must be between 1 and `config.MAX_LIMIT`.
 *    -fields {Object} Fields to query in the Mongo object format, e.g. {title :1}.
 *      The default is to query ONLY _id (note this is a difference from `find()`).
 *    -next {String} The value to start querying the page. Defaults to start at the beginning of
 *      the results.
 */
module.exports = (() => {
  var _ref = _asyncToGenerator(function* (collection, searchString, params) {
    if (_.isString(params.limit)) params.limit = parseInt(params.limit, 10);
    if (params.next) params.next = bsonUrlEncoding.decode(params.next);

    params = _.defaults(params, {
      query: {},
      limit: config.MAX_LIMIT
    });

    if (params.limit < 1) params.limit = 1;
    if (params.limit > config.MAX_LIMIT) params.limit = config.MAX_LIMIT;

    // We must perform an aggregate query since Mongo can't query a range when using $text search.

    const aggregate = [{
      $match: _.extend({}, params.query, {
        $text: {
          $search: searchString
        }
      })
    }, {
      $project: _.extend({}, params.fields, {
        _id: 1,
        score: {
          $meta: 'textScore'
        }
      })
    }, {
      $sort: {
        score: {
          $meta: 'textScore'
        },
        _id: -1
      }
    }];

    if (params.next) {
      aggregate.push({
        $match: {
          $or: [{
            score: {
              $lt: params.next[0]
            }
          }, {
            score: {
              $eq: params.next[0]
            },
            _id: {
              $lt: params.next[1]
            }
          }]
        }
      });
    }

    aggregate.push({
      $limit: params.limit
    });

    let response;

    const aggregateQuery = collection.aggregate(aggregate);
    const execMethod = aggregateQuery.toArray ? 'toArray' : 'exec';
    const results = yield aggregateQuery[execMethod]();

    const fullPageOfResults = results.length === params.limit;
    if (fullPageOfResults) {
      response = {
        results,
        next: bsonUrlEncoding.encode([_.last(results).score, _.last(results)._id])
      };
    } else {
      response = {
        results
      };
    }
    return response;
  });

  return function (_x, _x2, _x3) {
    return _ref.apply(this, arguments);
  };
})();