如何使用node-mysql在for循环中创建对象？

Question

我有“for”循环在一个函数中，我想使1对象而不是许多保存绘制调用。 有什么办法可以做到吗？在我的测试中，我发现我无法在connection.query之外创建var，它将包含来自哪个查询的数据。所以我甚至不能使用该查询中包含的全局变量。我对此很感兴趣，所以任何帮助都会很棒。包含在app.js

load_sent_mail: function(person_id, callback, socket) { 
    pool.getConnection(function(err, connection) { 
     connection.query('SELECT * FROM `mail` WHERE mail_sender = ' + person_id + '', function(err, mail_data) { 
      if (!err) { 
       for (var key in mail_data) { 
        var items_to_get_info = []; 
        if (mail_data[key].mail_spot_1 != 0) items_to_get_info.push(mail_data[key].mail_spot_1); 
        if (mail_data[key].mail_spot_2 != 0) items_to_get_info.push(mail_data[key].mail_spot_2); 
        if (mail_data[key].mail_spot_3 != 0) items_to_get_info.push(mail_data[key].mail_spot_3); 
        if (mail_data[key].mail_spot_4 != 0) items_to_get_info.push(mail_data[key].mail_spot_4); 
        if (items_to_get_info.length) { 
         connection.query('SELECT `person_items`.`id`, `items`.`item_image`, `items`.`item_place` FROM `person_items` INNER JOIN `items` ON `person_items`.`item_id` = `items`.`item_id` WHERE `person_items`.`id`IN (' + items_to_get_info.join(",") + ')', function(err, items_in_mail) { 
          if (!err) { 
           callback(null, items_in_mail); 
          } else { 
           console.log(err) 
          } 
         }); 
        } { 
         //0 items 
        } 
       } 
      } 
     }) 
     connection.release(); 
    }); 
} 

外部文件app.js

mail.load_sent_mail(person_id,function(err,items_in_mail){ 
    socket.emit('incoming_mail', items_in_mail); 
}); 

Answer 1

如果我正确理解你的问题，这并不解决您的问题：

load_sent_mail: function(person_id, callback, socket) { 
    pool.getConnection(function(err, connection) { 
     connection.query('SELECT * FROM `mail` WHERE mail_sender = ' + person_id + '', function(err, mail_data) { 
      if (!err) { 
       // Move this line before the loop 
       var items_to_get_info = []; 
       for (var key in mail_data) { 
        if (mail_data[key].mail_spot_1 != 0) items_to_get_info.push(mail_data[key].mail_spot_1); 
        if (mail_data[key].mail_spot_2 != 0) items_to_get_info.push(mail_data[key].mail_spot_2); 
        if (mail_data[key].mail_spot_3 != 0) items_to_get_info.push(mail_data[key].mail_spot_3); 
        if (mail_data[key].mail_spot_4 != 0) items_to_get_info.push(mail_data[key].mail_spot_4); 
       } 
       // Move this line after the loop 
       if (items_to_get_info.length) { 
        connection.query('SELECT `person_items`.`id`, `items`.`item_image`, `items`.`item_place` FROM `person_items` INNER JOIN `items` ON `person_items`.`item_id` = `items`.`item_id` WHERE `person_items`.`id`IN (' + items_to_get_info.join(",") + ')', function(err, items_in_mail) { 
         if (!err) { 
          callback(null, items_in_mail); 
         } else { 
          console.log(err) 
         } 
        }); 
       } 
      } 
     }) 
     connection.release(); 
    }); 
} 

I我想我在某个地方丢掉了一个支架，但我希望你明白了！