@conpago/mongo-cursor-pagination/dist/node/find.js

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

"use strict";
var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
const underscore_1 = require("underscore");
const aggregate_1 = __importDefault(require("./aggregate"));
const config_1 = __importDefault(require("./config"));
const query_1 = require("./utils/query");
const sanitizeParams_1 = __importDefault(require("./utils/sanitizeParams"));
/**
 * Performs a find() query on a passed-in Mongo collection, using criteria you specify. The results
 * are ordered by the paginatedField.
 *
 * @param {Collection} collection A collection object returned from the MongoDB library's.
 * @param {QueryParams} params
 * @param {object} params.query The find query.
 * @param {Number} params.limit The page size. Must be between 1 and `config.MAX_LIMIT`.
 * @param {object} params.fields Fields to query in the Mongo object format, e.g. {_id: 1, timestamp :1}.
 *      The default is to query all fields.
 * @param {String} params.paginatedField The field name to query the range for. The field must be:
 *        1. Orderable. We must sort by this value. If duplicate values for paginatedField field
 *          exist, the results will be secondarily ordered by the _id.
 *        2. Indexed. For large collections, this should be indexed for query performance.
 *        3. Immutable. If the value changes between paged queries, it could appear twice.
          4. Consistent. All values (except undefined and null values) must be of the same type.
 *      The default is to use the Mongo built-in '_id' field, which satisfies the above criteria.
 *      The only reason to NOT use the Mongo _id field is if you chose to implement your own ids.
 * @param {boolean} params.sortAscending Whether to sort in ascending order by the `paginatedField`.
 * @param {boolean} params.sortCaseInsensitive Whether to ignore case when sorting, in which case `paginatedField`
 * @param {boolean} params.getTotal Whether to fetch the total count for the query results
 *      must be a string property.
 * @param {String} params.next The value to start querying the page.
 * @param {String} params.previous The value to start querying previous page.
 * @param {String} params.after The _id to start querying the page.
 * @param {String} params.before The _id to start querying previous page.
 * @param {String} params.hint An optional index hint to provide to the mongo query
 * @param {object} params.collation An optional collation to provide to the mongo query. E.g. { locale: 'en', strength: 2 }. When null, disables the global collation.
 */
exports.default = async (collection, params) => {
    const projectedFields = params.fields;
    let response = {};
    if (params.sortCaseInsensitive) {
        // For case-insensitive sorting, we need to work with an aggregation:
        response = await (0, aggregate_1.default)(collection, Object.assign({}, params, {
            aggregation: params.query ? [{ $match: params.query }] : [],
        }));
    }
    else {
        // Need to repeat `params.paginatedField` default value ('_id') since it's set in 'sanitizeParams()'
        params = (0, underscore_1.defaults)(await (0, sanitizeParams_1.default)(collection, params), { query: {} });
        const cursorQuery = (0, query_1.generateCursorQuery)(params);
        const $sort = (0, query_1.generateSort)(params);
        // Support both the native 'mongodb' driver and 'mongoist'. See:
        // https://www.npmjs.com/package/mongoist#cursor-operations
        const findMethod = collection.findAsCursor ? "findAsCursor" : "find";
        const query = collection[findMethod]()?.project
            ? collection
                .find({ $and: [cursorQuery, params.query] })
                .project(params.fields)
            : collection[findMethod]({ $and: [cursorQuery, params.query] }, params.fields);
        /**
         * IMPORTANT
         *
         * If using collation, check the README:
         * https://github.com/mixmaxhq/mongo-cursor-pagination#important-note-regarding-collation
         */
        const isCollationNull = params.collation === null;
        const collation = params.collation || config_1.default.COLLATION;
        const collatedQuery = collation && !isCollationNull ? query.collation(collation) : query;
        // Query one more element to see if there's another page.
        const cursor = collatedQuery.sort($sort).limit(params.limit + 1);
        if (params.hint)
            cursor.hint(params.hint);
        const results = await cursor.toArray();
        response = (0, query_1.prepareResponse)(results, params);
        if (params.getTotal)
            response.totalCount = await collection.countDocuments(params.query);
    }
    // Remove fields that we added to the query (such as paginatedField and _id) that the user didn't ask for.
    const projectedResults = (0, query_1.filterProjectedFields)({
        projectedFields,
        results: response.results,
        sortCaseInsensitive: params.sortCaseInsensitive,
    });
    return { ...response, results: projectedResults };
};
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