node.js - 在 REST API 中合并 2 个查询的输出

Question

我正在使用 node.js restify 模块。我有一个 REST API，它以 json 格式输出单个 MySQL 查询的结果。这是API的代码；

var rest_api_get_list = function (app, url_name) {
    function respond(req, res, next) {
        var door_mac = req.query.door_mac;

        var connection = own_mysql.getMySQL_connection();

        var query_str =
                "SELECT doors.mac_addr, " +
                "sensors.sensor_type " +
                "FROM sensors " +
                "WHERE (doors.mac_addr = ?) "
            ;

        var query_var = [door_mac];

        var query = connection.query(query_str, query_var, function (err, rows, fields) {
            //if (err) throw err;
            if (err) {
                //throw err;
                console.log(err);
                logger.info(err);
            }
            else {
                res.send(rows);
            }
        }); 
        return next();
    }

    app.get(url_name, respond);
};

假设我有另一个类似这样的查询；

    var query_str_2 =
            "SELECT knobs.mac_addr, " +
            "furniture.furniture_type " +
            "FROM furnitures" +
            "WHERE (knobs.mac_addr = ?) "
        ;

我想合并 2 个 MySQL 查询 query_str 和 query_str_2 的输出，并让 REST API 以 json 格式返回结果。如何才能做到这一点？

更清楚地说，我正在考虑代码做这样的事情；

var rest_api_get_list = function (app, url_name) {
    function respond(req, res, next) {
        var door_mac = req.query.door_mac;

        var connection = own_mysql.getMySQL_connection();

        var query_str =
                "SELECT doors.mac_addr, " +
                "sensors.sensor_type " +
                "FROM sensors " +
                "WHERE (doors.mac_addr = ?) "
            ;

        var query_var = [door_mac];

        var query = connection.query(query_str, query_var, function (err, rows_output_1, fields) {
            //if (err) throw err;
        }); 

        var query_str_2 =
            "SELECT knobs.mac_addr, " +
            "furniture.furniture_type " +
            "FROM furnitures" +
            "WHERE (knobs.mac_addr = ?) "
        ;

        var query_2 = connection.query(query_str_2, query_var, function (err, rows_output_2, fields) {
            //if (err) throw err;

        }); 

        //How to display json output of rows_output_1 and rows_output_2?

        return next();
    }

    app.get(url_name, respond);
};

编辑:我开始悬赏以吸引使用 Promises 的答案。

Answer 1

用于管理异步控制流的模块 - 如 async - 可以帮助您。

例如:

function respond(req, res, next) {

    var door_mac = req.query.door_mac;
    var connection = own_mysql.getMySQL_connection();
    var query_var = [door_mac];

    async.parallel([
        function (callback) {

            var query_str =
                "SELECT doors.mac_addr, " +
                "sensors.sensor_type " +
                "FROM sensors " +
                "WHERE (doors.mac_addr = ?) "
            ;
            connection.query(query_str, query_var, callback); 
        },
        function (callback) {

            var query_str_2 =
                "SELECT knobs.mac_addr, " +
                "furniture.furniture_type " +
                "FROM furnitures" +
                "WHERE (knobs.mac_addr = ?) "
            ;
            connection.query(query_str_2, query_var, callback);
        }
    ], function (error, results) {

        // results[0] => result for query_str
        // results[1] => result for query_str_2
        // ... return next() or whatever
    })       
}