salix/modules/route/back/methods/cmr/downloadZip.js

const JSZip = require('jszip');

module.exports = Self => {
    Self.remoteMethodCtx('downloadZip', {
        description: 'Download a zip file with multiple cmrs pdfs',
        accessType: 'READ',
        accepts: [
            {
                arg: 'ids',
                type: 'string',
                description: 'The cmrs ids',
            }
        ],
        returns: [
            {
                arg: 'body',
                type: 'file',
                root: true
            }, {
                arg: 'Content-Type',
                type: 'string',
                http: {target: 'header'}
            }, {
                arg: 'Content-Disposition',
                type: 'string',
                http: {target: 'header'}
            }
        ],
        http: {
            path: '/downloadZip',
            verb: 'GET'
        },
        accessScopes: ['DEFAULT', 'read:multimedia']
    });

    Self.downloadZip = async function(ctx, ids, options) {
        const models = Self.app.models;
        const myOptions = {};
        const zip = new JSZip();

        if (typeof options == 'object')
            Object.assign(myOptions, options);

        const downloadAddZip = async id => {
            ctx.args = ctx.args || {};
            ctx.args.id = Number(id);
            const [data] = await models.Cmr.print(ctx, myOptions);
            zip.file(`${id}.pdf`, data, {binary: true});
        };

        ids = ids.split(',');
        const promises = ids.map(id => downloadAddZip(id));
        await Promise.all(promises);
        const zipStream = zip.generateNodeStream({streamFiles: true});
        return [zipStream, 'application/zip', `filename="cmrs.zip"`];
    };
};