function toDB(modelName, projectId, map = false, concurrency = 10) {
        if (!this.stream) {
            throw new Error(`${modelName} import error: no stream present!`);
        }

        map = map ? map : p21map[modelName];

        this.stream.pipe(pressure(function (data, cb) {
            const row = { projectId: projectId };
            const val = Object.values(data);

            if (map.length !== val.length) {
                return cb(new Error(`${modelName} import error: map.length != val.length`));
            }

            // map data (val) to row using map
            for (let i = 0; i < map.length; i++) {
                row[map[i]] = val[i].length ? val[i] : null;
            }

            db[modelName].create(row)
            .then(() => cb())
            .catch(function (err) {
                db.ImportError.create({
                    projectId : projectId,
                    model     : modelName,
                    data      : JSON.stringify(row),
                    error     : JSON.stringify(err) // JSON.stringify(err.errors)
                });

                cb();
            });
        }, concurrency));

        return new Promise((resolve, reject) => {
            this.stream.on('end', resolve);
            this.stream.on('error', reject);
            this.stream.resume();
        });
    }