Question

我希望从查询中获取数据，然后对存储在result中的项运行数组循环。然后使用从第一个查询获取的数组中的键从另一个查询中获取数据。

我所尝试的并没有给出我想要的结果，因为在sql查询完成并产生所需结果之前，数组循环用完了。

我尝试过使用async.series函数和async.map函数的解决方案，但结果并没有按照所需的顺序进行。

这是第一个查询的输出。我的目标是添加从第一个查询返回的选项ID的数组选项ID。

[
  {
    "id": 318,
    "name": "Sandwich Dosa",
    "price": 140,
    "option": ''
  },
  {
    "id": 319,
    "name": "Spi. Prem Uttappa",
    "price": 131,
    "option": '1,2'
  },
  {
    "id": 320,
    "name": "Paneer Spl. Prem Uttappa",
    "price": 140,
    "option": ''
  },
  {
    "id": 321,
    "name": "Spl. Spicy Uttappa",
    "price": 131,
    "option": ''
  }
]

希望构建为

[
  {
    "id": 318,
    "name": "Sandwich Dosa",
    "price": 140,
    "option": ''
  },
  {
    "id": 319,
    "name": "Spi. Prem Uttappa",
    "price": 131,
    "option": [{
      id:'1',
      name:'Regular',
      price:'89',
    },
    {
      id:'2',
      name:'Spicy',
      price:'119',
    }]
  },
  {
    "id": 320,
    "name": "Paneer Spl. Prem Uttappa",
    "price": 140,
    "option": ''
  },
  {
    "id": 321,
    "name": "Spl. Spicy Uttappa",
    "price": 131,
    "option": ''
  }
]

这是我目前正在试图实现的代码

var data = {
  "error": 1,
  "items": ""
};

connection.query("SELECT * FROM  items WHERE status=1 AND  menu_grp_id=" + req.params.sid, function(err, rows, fields) {
  var items = []; // temporary holder for items

  if(err) { throw err } else {
  if(rows.length != 0) {
    for (var key in rows) {
      // Holding Item properties
      var item = {
        id: '',
        name: '',
        price: '',
        option: ''
      };
      item.id = rows[key].id;
      item.name = rows[key].item_name;
      item.price = rows[key].price;
      item.option = rows[key].option;

      items.push(item); // pushing item object into    items array
    }
    data["error"] = 0;      
    data['items'] = items;
    if((data['items'].length > 0)) {
      for(i = 0; i < data['items'].length; i++) {
        if(data['items'][i].option == "") {
          data['items'][i].option = [];
        } else {
          var array = data['items'][i].option.split(",")
          data['items'][i].option = array;
        }
      }
    }
    res.json(data); // sending JSON Data
  } else {
    data["error"] = 0;
    data["items"] = 'No item Found..';
    res.json(data); //  sending JSON Data
  }}
});

Answer 1

可能我在这里有点晚了，但我认为async.waterfall就是你所需要的。

async.waterfall([
    function(cb){
        connection.query("SELECT * FROM  items WHERE status=1 AND  menu_grp_id=" + req.params.sid, function(err, rows, fields) {
            //manipulate your data as you wish
            data = synchronousManipolutionOfYourData();
            cb(null, data);
        });
    },
    function(data, cb){
        //data here stores the data you passed as a second parameter in the preciding callback
       //execute your second query with the data you got from the first query.
       cb(null, dataManipulatedAfterSecondQuery)//and so on
    }, 
    //other functions if you need other queries
], function(){
    done;
});

如何链接在节点中相互依赖的sql查询

1 个答案: