@tepez/mongo-cursor-pagination/dist/node/utils/sanitizeParams.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 bsonUrlEncoding = require('./bsonUrlEncoding');
const getPropertyViaDotNotation = require('./getPropertyViaDotNotation');
const config = require('../config');

module.exports = (() => {
  var _ref = _asyncToGenerator(function* (collection, params) {
    if (params.previous) params.previous = bsonUrlEncoding.decode(params.previous);
    if (params.next) params.next = bsonUrlEncoding.decode(params.next);

    params = _.defaults(params, {
      limit: config.DEFAULT_LIMIT,
      paginatedField: '_id'
    });

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

    // If the paginated field is not _id, then it might have duplicate values in it. This is bad
    // because then we can't exclusively use it for our range queries (that use $lt and $gt). So
    // to fix this, we secondarily sort on _id, which is always unique.
    const shouldSecondarySortOnId = params.paginatedField !== '_id';

    //
    // params.after - overides params.next
    //
    // The 'after' param sets the start position for the next page. This is similar to the
    // 'next' param, with the difference that 'after' takes a plain _id instead of an encoded
    // string of both _id and paginatedField values.
    if (params.after) {
      if (shouldSecondarySortOnId) {
        // Since the primary sort field is not provided by the 'after' pagination cursor we
        // have to look it up when the paginated field is not _id.
        const doc = yield collection.findOne({ _id: params.after }, { [params.paginatedField]: true, _id: false });
        if (doc) {
          // Handle usage of dot notation in paginatedField
          const prop = getPropertyViaDotNotation(params.paginatedField, doc);
          params.next = [prop, params.after];
        }
      } else {
        params.next = params.after;
      }
    }

    //
    // params.before - overides params.previous
    //
    // The 'before' param sets the start position for the previous page. This is similar to the
    // 'previous' param, with the difference that 'before' takes a plain _id instead of an encoded
    // string of both _id and paginatedField values.
    if (params.before) {
      if (shouldSecondarySortOnId) {
        // Since the primary sort field is not provided by the 'before' pagination cursor we
        // have to look it up when the paginated field is not _id.
        const doc = yield collection.findOne({ _id: params.before }, { [params.paginatedField]: true, _id: false });
        if (doc) {
          // Handle usage of dot notation in paginatedField
          const prop = getPropertyViaDotNotation(params.paginatedField, doc);
          params.previous = [prop, params.before];
        }
      } else {
        params.previous = params.before;
      }
    }

    // The query must always include the paginatedField so we can construct the cursor.
    if (params.fields) {
      params.fields = _.extend({
        _id: 0 // Mongo includes this field by default, so don't request it unless the user wants it.
      }, params.fields);

      if (!params.fields[params.paginatedField]) {
        params.fields[params.paginatedField] = 1;
      }
    }

    return params;
  });

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

  return sanitizeParams;
})();