Question

我尝试使用express和node-mysql将一些遗留数据从mysql数据库导出为JSON。下面的SQL工作正常。我正在努力用一种简单的方式来加入“结果”＃39; getOwnerID和compVouchers中返回的每一行的数据。

我也使用async.js跟随另一个帖子，虽然我不确定这有帮助。但是，如果我可以逃避不使用它可能会更好。

  //join some tables to get comprehensive voucher data 
    exports.compVouchers = function(req, res) {
        var advertType = '"discount_voucher_all_CANCELLED"';
        if (connection) {
        connection.query('SELECT V.id AS voucher_id, V.title, V.description, V.discount, V.customers_total, V.advert_type, ' +
            'V.customers_redeemed, V.start_date, V.expiry_date, V.redemption_code, ' +
            'K.image, G.latitude, G.longitude FROM '+dbname+'.vouchers AS V ' +
            'LEFT JOIN '+dbname+'.iag_key_tags AS K ON ( V.id = K.id ) ' +
            'LEFT JOIN '+dbname+'.iag_geo_tags AS G ON ( V.id = G.id ) ' +
            'WHERE V.advert_type like '+advertType , function(err, rows, fields) {
                if (err) throw err;
                console.log("Got "+rows.length+" Vouchers:");
               // now get each vouchers owner id
                async.map(rows, getOwnerID, function(err, results){
                res.writeHead(200, {'Content-Type': 'text/plain'});
                res.end(JSON.stringify(results));
                res.end();
                });

            });

        }

    };

        function getOwnerID(voucher, callback) {
            connection.query('SELECT parent_tagid AS owner_id FROM '+dbname+'.iag_key_tag_relationships WHERE TYPE =2 AND tagid =  '+ voucher.voucher_id,  function(err, info) {
                if(err) {
                    console.log(err);
                    return callback(err);
                }
                else {
                    return callback(null, info);
                }
            });
        }

所以

res.end（JSON.stringify（结果））; //仅打印每张优惠券的所有owner_id

res.end（JSON.stringify（行））; //打印每个凭证的数据，但不打印owner_id

Combining node-mysql result rows into single JSON return for node.js无法解决问题，但正如您所见，我已尝试按照该主题中的建议行事。

Answer 1

这里有一些美感而不是在演出:) 试试这个：

var result={}, c=rows.length;
function getOwnerID(voucher, cb){
           connection.query('SELECT ...',  function(err, info) {
                if(err) console.log(err);
                else result[info] = voucher;
                if(!--c)return cb();
            });
}

while(rows.length){
 getOwnerID(rows.pop(), function(){
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end(JSON.stringify(results));// {"owner1":{voucher1}, "owner2":{voucher2}}
  res.end();
 })
}

Answer 2

好的伙计们（感谢@vp_arth在一个让我接近的有趣方向上轻推我，错字结果应该是btw的结果）

所以，无论如何，我最终得到了一个黑客解决方案，我使用.push underscore.js和.replace来帮助我清理JSON数据，这样我就可以在像MongoDB这样的nosql数据库中使用它。。

   //declare global array variable... there must be a more elegant solution
    var compV = [];
    exports.compVouchers = function(req, res) {
        var advertType = '"discount_voucher_all_CANCELLED"';
        if (connection) {
        connection.query('SELECT V.id AS voucher_id, V.title, V.description, V.discount, V.customers_total, V.advert_type, ' +
            'V.customers_redeemed, V.start_date, V.expiry_date, V.redemption_code, ' +
            'K.image, G.latitude, G.longitude FROM '+dbname+'.vouchers AS V ' +
            'LEFT JOIN '+dbname+'.iag_key_tags AS K ON ( V.id = K.id ) ' +
            'LEFT JOIN '+dbname+'.iag_geo_tags AS G ON ( V.id = G.id ) ' +
            'WHERE V.advert_type like '+advertType , function(err, rows, fields) {
                if (err) throw err;
                // now get each vouchers owner id
                console.log("Got "+rows.length+" Vouchers:");
                async.each(rows, getOwnerID, function(err, results){
                res.writeHead(200, {'Content-Type': 'text/plain'});
                // now user underscore.js to clean up JSON
                var finalComp = JSON.stringify(un.flatten(un.compact(compV)));
                // finally use replace to customise the known output to merging the voucher and owner into single JSON documents
                var finalComp2 = finalComp.replace(/},{"owner_id/g,',"owner_id'); //not happy with this but it works
                res.write(finalComp2);
                res.end();
                });

            });

        }

    };

        function getOwnerID(voucher, callback) {
            connection.query('SELECT parent_tagid AS owner_id FROM '+dbname+'.iag_key_tag_relationships WHERE TYPE =2 AND tagid =  '+ voucher.voucher_id,  function(err, owner) {
                if(err) {
                    console.log(err);
                    return callback(err);
                }
                else {
                    var arr = [];
                    arr.push(voucher);
                    arr.push(owner);
                    compV.push(arr);  //append to global array variable
                    return callback(null, compV); // doesn't return anything??
                }
            });
        }

也许有更优雅的合并方式

[{＆＃34; F1_field1＆＃34;：＆＃34; F1_value1＆＃34;＆＃34; F1_field2＆＃34;：＆＃34; F1_value2＆＃34;}，{＆＃34; F2_field1＆＃34 ;：＆＃34; F2_value2＆＃34;}]

进入

[{＆＃34; F1_field1＆＃34;：＆＃34; F1_value1＆＃34;＆＃34; F1_field2＆＃34;：＆＃34; F1_value2＆＃34;＆＃34; F2_field1＆＃34 ;: ＆＃34; F2_value2＆＃34;}]

这是我的评论/想法的最终代码

你现在还需要npm安装下划线添加到异步并在变量中声明它们...更不用说node-mysql和express ...我已经使用了＆＃34; un＆＃34;而不是＆＃34; _＆＃34;所以我不会对以后可能看起来像jquery的代码感到困惑。

如何在express.js中加入两个node-mysql.js函数的结果

2 个答案: