@sap/odata-v4/lib/uri/ExpandHelper.js

OData V4.0 server library

'use strict';

const ExpandItem = require('./ExpandItem');
const SelectItem = require('./SelectItem');
const TransformationKind = require('./apply/Transformation').TransformationKind;
const QueryOption = require('./UriInfo').QueryOptions;
const NotImplementedError = require('../errors/NotImplementedError');

/**
 * ExpandHelper has utility methods for extracting and combining expand information.
 */
class ExpandHelper {
    /**
     * Merge expand information from a path into existing expand items.
     * @param {?(UriResource[])} pathSegments the path
     * @param {ExpandItem[]} items the expand information
     * @private
     */
    static _mergeExpandPathIntoExpandItems(pathSegments, items) {
        if (pathSegments[0].getNavigationProperty()) {
            let item = items.find(expItem => expItem.getPathSegments()[0].getNavigationProperty()
                === pathSegments[0].getNavigationProperty());
            if (!item) item = new ExpandItem().setPathSegments([pathSegments[0]]);
            if (pathSegments[1]) {
                if (pathSegments[1].getNavigationProperty()) {
                    let innerItems = item.getOption(QueryOption.EXPAND) || [];
                    ExpandHelper._mergeExpandPathIntoExpandItems(pathSegments.slice(1), innerItems);
                    if (innerItems.length) item.setOption(QueryOption.EXPAND, innerItems);
                }
                item.setOption(QueryOption.SELECT,
                    (item.getOption(QueryOption.SELECT) || [])
                        .concat(new SelectItem().setPathSegments([pathSegments[1]])));
            }
            if (!items.includes(item)) items.push(item);
        }
    }

    /**
     * Extract expand information from the $apply system query option.
     * @param {?(Transformation[])} transformations transformations from $apply system query option
     * @returns {ExpandItem[]} the extracted expand information
     * @private
     */
    static _getExpandFromApply(transformations) {
        let items = [];
        if (!transformations) return items;
        for (const transformation of transformations) {
            if (transformation.getKind() === TransformationKind.GROUP_BY) {
                for (const groupByItem of transformation.getGroupByItems()) {
                    if (groupByItem.isRollupAll() || groupByItem.getRollup().length) {
                        throw new NotImplementedError('Construction of expand items for rollup is not supported.');
                    }
                    const pathSegments = groupByItem.getPathSegments();
                    if (!pathSegments.length) continue;
                    ExpandHelper._mergeExpandPathIntoExpandItems(pathSegments, items);
                }
            } else if (transformation.getKind() === TransformationKind.AGGREGATE) {
                items = [];
            }
        }
        return items;
    }

    /**
     * Extract expand information from the request.
     * @param {OdataRequest} request the request
     * @returns {ExpandItem[]} the extracted expand information
     */
    static getFinalExpand(request) {
        const uriInfo = request.getUriInfo();
        let expandItems = ExpandHelper._getExpandFromApply(uriInfo.getQueryOption(QueryOption.APPLY));
        if (!expandItems.length) expandItems = request.getDeepInsertExpand();
        if (!expandItems.length) expandItems = uriInfo.getQueryOption(QueryOption.EXPAND) || [];
        return expandItems;
    }
}

module.exports = ExpandHelper;