完全QUERY2クエリ1の結果を取得する前に、私は推測によるノードのjsのイベントループの非同期性に1つのクエリの結果は、私が直面しています別のクエリの非同期ノードJSここ

Question

//global array to store dynamodb query result 
    var store = []; 

    //function that to retrive socket data based on user email id as a hash key and give json to pass into query by taking email as input 
    var getSocketParams = (email) => { 
    return { 
     TableName: "socketSockets", 
     KeyConditionExpression: "user_id = :em", 
     ExpressionAttributeValues: { 
      ":em": email 
     } 
    }; 
} 
//query 1 which retrive all sockets details from respective table 
var q1 = (callback) => { 
    retrivalDetail(getSocketParams(em), function(err, res) { 
     if (err) callback(err, null); 
     callback(null, res); 
    }); 
}; 

//query 2 take input as a result of query 1 response and second a callback 
var q2 = (res, callback) => { 
    //here i made some logic to check callback is not executed until all items in query 1 response executed and that respective data fetched from respective table if have any 
    var ctr = 0; 
    res.Items.forEach(function(d) { 
     var payload_params_l = { 
      TableName: "socketPayload", 
      KeyConditionExpression: "#mac = :mac", 
      ExpressionAttributeNames: { 
       "#mac": "mac" 
      }, 
      ExpressionAttributeValues: { 
       ":mac": d.socket_id 
      }, 
      ScanIndexForward: false, 
      Limit: 1 
     }; 
     retrivalDetail(payload_params_l, function(err, res) { 
      if (err) callback(err, null); 
      store.push(res); 
      ctr++;         
      if (ctr === Object.keys(res.Items).length) { 
       callback(null, store); 
      } 
     }); 
    }); 
}; 
//my function call to excute query 1 and query 2 here problem is due to asynchronous nature of node js i guess before getting query 1 result completely query2 will be start executing so i place q2 inside q1 callback here how can i retrive all data from q2 inside loop and pass all data after finishing loop to q2 callback 
function call() { 
    q1(function(err, res) { 
     if (err) done(err, null); 
     q2(res, function(err, res) { 
      if (err) done(err, null); 
      //final function done which gives response to API request done(error ,response) 
      done(null, res); 
     }); 
    }); 
}; 
call(); 

問題への入力として渡している2デシベルクエリでの実行q2をQ2コールバックに入れてください。このコードを改善するための良い提案があります。ループ内のq2からすべてのデータを取得し、q2コールバックにループを完了した後にすべてのデータを渡すことができます。

私は初心者です可能であればノードjsの非同期パッケージを非同期モジュールを使用してこれについてどのような助けになるか

Answer 1

関数呼び出し（）は、それはあなたがhttps://caolan.github.io/async/docs.html#waterfallをしたい場合は、async.waterfall使用することができ、オーケーだが、機能Q2のために、私のように.......

//global array to store dynamodb query result 
    var store = []; 

    //function that to retrive socket data based on user email id as a hash key and give json to pass into query by taking email as input 
    var getSocketParams = (email) => { 
    return { 
     TableName: "socketSockets", 
     KeyConditionExpression: "user_id = :em", 
     ExpressionAttributeValues: { 
      ":em": email 
     } 
    }; 
} 
//query 1 which retrive all sockets details from respective table 
var q1 = (callback) => { 
    retrivalDetail(getSocketParams(em), function(err, res) { 
     if (err) callback(err, null); 
     callback(null, res); 
    }); 
}; 

var q2 = (res, callback) => { 

    async.forEachOf(res.Item, function (d, index, done) { 

    var payload_params_l = { 
      TableName: "socketPayload", 
      KeyConditionExpression: "#mac = :mac", 
      ExpressionAttributeNames: { 
       "#mac": "mac" 
      }, 
      ExpressionAttributeValues: { 
       ":mac": d.socket_id 
      }, 
      ScanIndexForward: false, 
      Limit: 1 
     }; 
     retrivalDetail(payload_params_l, function(err, res) { 
      if (err) { 
       done(err, null); 
      } else { 
       store.push(res); 
       done(null); 
      } 
     }); 
    }, 
    function (error) { 
     // la fin du traitement de tous les records 
     if (error) callback(error, null) 
     else callback(null, store); 
    }); 
} 



//my function call to excute query 1 and query 2 here problem is due to asynchronous nature of node js i guess before getting query 1 result completely query2 will be start executing 
//so i place q2 inside q1 callback here how can i retrive all data from q2 inside loop and pass all data after finishing loop to q2 callback 
function call() { 
    q1(function(err, res) { 
     if (err) done(err, null); 
     q2(res, function(err, res) { 
      if (err) done(err, null); 
      //final function done which gives response to API request done(error ,response) 
      done(null, res); 
     }); 
    }); 
};