@house-agency/brewstore/relational.js

The Brewery Storage

/**
 * Handles Relational Data Storage ~= MySQL
 * It's using Sequelize
 */

const _ = require('lodash');
const conf = require('@house-agency/brewtils/config');
const log = require('@house-agency/brewtils/log');
const q = require('q');
const Sequelize = require('sequelize');

/**
 * Sets up the Sequelize by getting the database
 * connection properties from config.
 * In this way, we'll have a global database connection pool.
 *
 * @returns {object} Promise with sequelize instance
 */
function connect() {
    return conf('storage.relational')
    .then(props => {
        log('debug', 'Connecting to relational storage', props);

        return new Sequelize(
            props.database,
            props.username,
            props.password,
            {
                host: props.host,
                dialect: props.engine,
                dialectOptions: {
                    multipleStatements: true
                },
                pool: {
                    max: props.pool.max
                },
                logging: props.logging
            }
        );
    });
}

const connection = connect();

/**
 * Creates a database model
 *
 * @param {string} name Table name
 * @param {object} fields Table fields
 * @param {object} dependent_promise An optional promise that must
 * be resolved before creating table. Usable for relations.
 *
 * @return {object} Promise with the model
 */
function create_table(name, fields, dependent_promise) {
    return q.all([
        connection,
        dependent_promise != null ? dependent_promise : q()
    ])
    .spread(database => {
        const table = database.define(name, fields);

        return table.sync()
        .then(() => database.getQueryInterface().describeTable(name))
        .then(columns => auto_add_columns(
            database.getQueryInterface(),
            name,
            columns,
            fields
        ))
        .then(() => table)
        .catch(error => {
            log('fatal', 'Error when defining model', name, fields, error);

            throw error;
        });
    });
}

/**
 * Automaticly add non-existing columns to table
 *
 * @param {object} query Query interface
 * @param {string} table Table name
 * @param {object} current Existing columns
 * @param {object} columns The wanted set of fields
 *
 * @returns {void} Empty promise
 */
function auto_add_columns(query, table, current, columns) {
    return _.reduce(columns, (promise, props, name) => {
        return promise
        .then(() => {
            if (!_.has(current, name)) {
                return query.addColumn(table, name, props);
            }
        });
    }, q());
}

module.exports = Object.assign(
    connection,
    {
        create_table: create_table
    }
);