Node.js mysql helper module for simple queries

pooled-query.js

/* using connection pool (recommended) */

var mysql = require('mysql');
var log = require('./mylogger');

var local_context = this;

var SimpleQueryException = function (message) {
    this.name = 'SimpleQueryException';
    this.message = message;
};
SimpleQueryException.prototype.toString = function () {
    return this.name + ': ' + this.message;
};

var configureSimpleQuery = function (db_config, context) {
    context = context || local_context;
    
    if ( ! ('connectionLimit' in db_config)) {
        db_config.connectionLimit = 100;
    }
    
    var connection_pool = mysql.createPool(db_config);
    
    /* end all connections on exit */
    //process.stdin.resume();
    process.on('exit', function (code) {
        connection_pool.end();
        log('Database connection pool closed.');
        process.exit(code);
    });
    /* catch Ctrl+C */
    process.on('SIGINT', function () {
        process.exit(0);
    });
    
    var conn_ids = [];
    
    connection_pool.on('connection', function (connection) {
        if (conn_ids.indexOf(connection.threadId) > -1) {
            log('Database connection reused [connection-id: ' + connection.threadId + ']');
        } else {
            conn_ids.push(connection.threadId);
            log('Database connection created [connection-id: ' + connection.threadId + ']');
        }
    });
    
    var simpleQuery = function () {
        var query, options, callback;
        
        if (arguments.length < 2) {
            
            throw new SimpleQueryException('Atleast 2 parameters required.');
            
        } else if (arguments.length > 2) {
            
            query = arguments[0];
            options = arguments[1];
            callback = arguments[2];
            
        } else {
            
            query = arguments[0];
            callback = arguments[1];
            
        }
        
        connection_pool.getConnection(function (err, connection) {
            if (err) {
                connection.release();
                callback.call(context, err, [], []);
                return;
            }
            
            if (options) {
                connection.query(query, options, function (err, results, fields) {
                    connection.release();
                    callback.call(context, err, results, fields);
                });
            } else {
                connection.query(query, function (err, results, fields) {
                    connection.release();
                    callback.call(context, err, results, fields);
                });
            }
            
            /*connection.on('error', function(err) {
                callback.call(context, err, [], []);
                return;
            });*/
        });
    };
    
    return simpleQuery;
};

module.exports = configureSimpleQuery;

simple-query.js

/* using new connection per request */

var mysql = require('mysql');
var log = require('./mylogger');

var local_context = this;

var SimpleQueryException = function (message) {
    this.name = 'SimpleQueryException';
    this.message = message;
};
SimpleQueryException.prototype.toString = function () {
    return this.name + ': ' + this.message;
};

var configureSimpleQuery = function (db_config, context) {
    context = context || local_context;
    
    var SimpleQuery = function () {
        var query, options, callback;
        
        if (arguments.length < 2) {
            
            throw new SimpleQueryException('Atleast 2 parameters required.');
            
        } else if (arguments.length > 2) {
            
            query = arguments[0];
            options = arguments[1];
            callback = arguments[2];
            
        } else {
            
            query = arguments[0];
            callback = arguments[1];
            
        }
        
        var db = mysql.createConnection(db_config);
        
        db.connect(function (err) {
            if (err) {
                callback.call(context, err, [], []);
                return;
            }
            log('Database connected! [connection-id: ' + db.threadId + ']');
        });
        
        if (options) {
            db.query(query, options, function (err, results, fields) {
                callback.call(context, err, results, fields);
            });
        } else {
            db.query(query, function (err, results, fields) {
                callback.call(context, err, results, fields);
            });
        }
        
        db.on('error', function (err) {
            callback.call(context, err, [], []);
        });
        
        db.end(function (err) {
            if (err) {
                log().error('DB Error!', err);
                return;
            }
            log('Database disconnected! [connection-id: ' + db.threadId + ']');
        });
    };
    
    return SimpleQuery;
};

module.exports = configureSimpleQuery;