nodejs async.parallel工作不正常

Question

嘗試從redis讀取數據然後以json格式將其發送給用戶時，我無法獲得正確的輸出。

這是我的代碼

//API to get slot for a particular date range 
app.get('/listcapacity/:ticketid/:fromdate/:todate', function(req, res) { 
    var id = req.params.ticketid; 
    var fromdate = req.params.fromdate; 
    var todate = req.params.todate; 
    var result = {}; 
    var data_output = []; 
    var asyncTasks = []; 
    var currentDate = new Date(fromdate); 
    var between = []; 
    var end = new Date(todate); 

    while (currentDate <= end) { 
     var tempdate = new Date(currentDate).toISOString(); 
     var dump = tempdate.toString().split("T"); 
     between.push(dump[0]); 
     currentDate.setDate(currentDate.getDate() + 1); 
    } 

    between.forEach(function(entry) { 

     asyncTasks.push(function(callback) { 
      client.exists(id+entry, function (err, reply) { 
       if (reply === 1) { 
        console.log("Found"); 
        client.get(id+entry, function (err, reply) { 
         var output = JSON.parse(reply); 
         data_output = data_output.concat(output); 
        }); 
       } 
       callback(); 
      }); 
     }); 

    }); 

    async.parallel(asyncTasks, function(){ 
     // All tasks are done now 
     result['data'] = data_output; 
     result['response'] = 1; 
     result['message'] = 'vacancies list fetched successfully!'; 
     res.json(result); 
    }); 

}); 

我總是得到輸出{"data":[],"response":1,"message":"vacancies list fetched successfully!"} 即使我已經檢查密鑰是那裏的Redis它總是由應用程序找到了。 由於某些原因，redis部分在數據發送給用戶之後得到執行。這是爲什麼發生？我知道redis在async中工作，因此使用async.parallel函數來處理這個問題，但即使如此，我最終也遇到了同樣的問題，如果我不想使用異步的話就會遇到同樣的問題。這是什麼原因？

Answer 1

client.get是一個異步操作，你必須在那裏回調。另外，你需要一個else語句，你需要在那裏回調：

//API to get slot for a particular date range 
app.get('/listcapacity/:ticketid/:fromdate/:todate', function (req, res) { 
    var id = req.params.ticketid; 
    var fromdate = req.params.fromdate; 
    var todate = req.params.todate; 
    var result = {}; 
    var data_output = []; 
    var asyncTasks = []; 
    var currentDate = new Date(fromdate); 
    var between = []; 
    var end = new Date(todate); 

    while (currentDate <= end) { 
    var tempdate = new Date(currentDate).toISOString(); 
    var dump = tempdate.toString().split("T"); 
    between.push(dump[0]); 
    currentDate.setDate(currentDate.getDate() + 1); 
    } 

    between.forEach(function (entry) { 

    asyncTasks.push(function (callback) { 
     client.exists(id + entry, function (err, reply) { 
     if (reply === 1) { 
      console.log("Found"); 
      client.get(id + entry, function (err, reply) { 
      var output = JSON.parse(reply); 
      data_output = data_output.concat(output); 

      return callback(); 
      }); 
     } else { 
      return callback(); 
     } 
     }); 
    }); 

    }); 

    async.parallel(asyncTasks, function() { 
    // All tasks are done now 
    result['data'] = data_output; 
    result['response'] = 1; 
    result['message'] = 'vacancies list fetched successfully!'; 
    res.json(result); 
    }); 

});