@sap/xsodata/lib/uri/expandSelectTreeBuilder.js

Expose data from a HANA database as OData V2 service with help of .xsodata files.

'use strict';

const InternalError = require('./../utils/errors/internalError');

function NavExp() {
    this.showAllProperties = true; //default show property, and navprop as link
    this.expandAllAvailExpands = true; //default expand all available navigations from $expand query

    this.isStar = false; //overwrite the .properties
    this.properties = []; // explicitly shown properties

    this.expandNavigations = []; // explicitly expanded navigations, means
    // the navigation is defined in $expand and $select

    this.availableExpands = {}; // available expands defined by $expand
}

NavExp.prototype.toPureJsonObject = function () {
    const ret = {
        showAllProperties: this.showAllProperties,
        expandAllAvailExpands: this.expandAllAvailExpands,
        isStar: this.isStar,
        properties: this.properties,
        expandNavigations: this.expandNavigations,
        availableExpands: {},
    };

    for (const exp in this.availableExpands) {
        if (this.availableExpands.hasOwnProperty(exp)) {
            ret.availableExpands[exp] =
                this.availableExpands[exp].toPureJsonObject();
        }
    }
    return ret;
};

NavExp.prototype.getNav = function (name) {
    return this.availableExpands[name];
};

NavExp.prototype.addNav = function (name, nav) {
    this.availableExpands[name] = nav;
    return this.availableExpands[name];
};

NavExp.prototype.applySelect = function (select) {
    const part = select.shift();

    if (part === '*') {
        this.isStar = true;
        this.expandAllAvailExpands = false;
    } else {
        this.showAllProperties = false;
        this.expandAllAvailExpands = false;
        const nav = this.availableExpands[part];

        if (nav) {
            if (this.properties.indexOf(part) === -1) {
                this.properties.push(part);
                //also a property which is not in the availNavigation list can be a navigation property
            }

            if (this.expandNavigations.indexOf(part) === -1) {
                this.expandNavigations.push(part);
            }
            if (select.length > 0) {
                nav.applySelect(select);
            }
        } else {
            if (this.properties.indexOf(part) === -1) {
                this.properties.push(part);
                //also a property which is not in the availNavigation list can be a navigation property
            }

            if (select.length > 0) {
                throw new InternalError('part to long');
            }
        }
    }
};

function processSelects(selects, tree) {
    for (const select of selects) {
        tree.applySelect(select);
    }
}

function createExpandTree(expandClauses) {
    const tree = new NavExp();
    if (expandClauses) {
        for (const expandClause of expandClauses) {
            let root = tree;

            for (const expandItem of expandClause) {
                const nav = root.getNav(expandItem);
                if (nav !== undefined) {
                    root = nav;
                } else {
                    root = root.addNav(expandItem, new NavExp());
                }
            }
        }
    }
    return tree;
}

function processExpandSelectTree(expands, selects) {
    const tree = createExpandTree(expands);
    if (selects) {
        processSelects(selects, tree);
    }

    return tree;
}

exports.processExpandSelectTree = processExpandSelectTree;