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node.js - 如何快速执行嵌套 for 循环中编写的等待函数

问题描述

也许我的问题标题是错误的。但我在解释身体的一切。我的问题是我正在为学生详细信息打一个 API。这给了多个学生记录。

响应示例

    {
                    "TotalRecords": "372",
                    "StudentName": "John Carter",
                    "StudentImage": "",
                    "AnotherKey": "Another Value",
                    "AnotherKey1": "Another Value1",
                    "ClassDetail": [
                        {"class":"5","rollnumber":"123"},
                        {"class":"6","rollnumber":"456"},
                        {"class":"7","rollnumber":"678"}
                    ],
                    "ChildCenterLocationList": [
                        {
                            "CenterLocationId": "4",
                            "CenterLocationName": "Stockton"
                        }
                    ]
                    
    },
    {
                    "TotalRecords": "372",
                    "StudentName": "John Luke",
                    "StudentImage": "",
                    "AnotherKey": "Another Value",
                    "AnotherKey1": "Another Value1",
                    "ClassDetail": [
                        {"class":"5","rollnumber":"123"},
                        {"class":"6","rollnumber":"456"},
                        {"class":"7","rollnumber":"678"}
                    ],
                    "ChildCenterLocationList": [
                        {
                            "CenterLocationId": "4",
                            "CenterLocationName": "Stockton"
                        }
                    ]
                    
    }

为此，我在控制器页面上写了简单的逻辑

exports.GetChildsDetail = async function (req, res) {
try {
        
       let parms = [req.userId, req.query.Date];
       let spRes = await _dbContaxt.ExcuteQuery(StoredProcdureName, parms);
       if (spRes != null && spRes.length > 0) {
           //till now everything is good. I am getting the response properly as I mentioned above and sending it to client
        }
}


})

现在再次要求您必须使用 ClassDetail 键中的 rollnumber 为每个学生找到每个班级的主题详细信息和标记表详细信息。

所以 ClassDetail 键将类似于

"ClassDetail": [
                    {
                    "class":"5",
                    "rollnumber":"123",
                    "subjectDetail": [{'subject1detail'},{'subject1detail'},{'subject1detail'}]
                    "mrksheetDetail": [{'this is again an complex object'}]
                    },
                    {
                    "class":"6",
                    "rollnumber":"456",
                    "subjectDetail": [{'subject1detail'},{'subject1detail'},{'subject1detail'}]
                    "mrksheetDetail": [{'this is again an complex object'}]
                    }
                    {
                    "class":"7",
                    "rollnumber":"678",
                    "subjectDetail": [{'subject1detail'},{'subject1detail'},{'subject1detail'}]
                    "mrksheetDetail": [{'this is again an complex object'}]
                    }
               ]

所以我再次像上面那样做

exports.GetChildsDetail = async function (req, res) {
    try {
            
           let parms = [req.userId, req.query.Date];
           let spRes = await _dbContaxt.ExcuteQuery(StoredProcdureName, parms);
           if (spRes != null && spRes.length > 0) {
               for (var clients of spRes.ResData) {
                 let arrSubCodes = [];
                  for (var authList of clients.ClassDetail) {
                   let parms1 = [req.userId, authList.rollnumber, req.query.Date];
                        let spRes1 = await _dbContaxt.ExcuteQuery(_StoredProcedureForSubject, parms1);
                      if (spRes1 != null && spRes1.length > 0) {
                       arrSubCodes.push(singleData1.ResData.SubjectDetail)
                      }
                  }
                   clients.subjectDetail= arrSubCodes;
               }
            }
    }
    
    
    })

结果来了，但它需要太多时间，几乎 2 分钟。我只有10个学生。所以我尝试了另一种更快的方法，但它只适用于循环的最后一个rollnumber。代码在调用主循环之后。

if (spRes != null && spRes.length > 0) {
await Promise.all( spRes.ResData.map(async (item) => {
    
   return new Promise((resolve, reject) => {
       for (var i in item.ClassDetail) {
        let parms2 = [req.userId, item.ClassDetail[i].rollnumber];
         _dbContaxt.ExcuteQuery(_dbHelper._StoredProcedureForSubject, parms2).then(spRes1=>{
             if (spRes1 != null && spRes1.length > 0) {
                item.ClassDetail[i].subjectDetail= spRes1.ResData;
                resolve()
             }
          })
       }
   })

 }))
}

此代码仅适用于最后一个 rollnumber。如果我在 ClassDetail 键中有多个记录，那么它仅适用于最后一条记录。

标签： node.jsexpresspromiseasync-awaitcallback

解决方案

正如@bergi所说，我已经尝试过并且工作正常

if (spRes != null && spRes.length > 0) {
await Promise.all( spRes.ResData.map(async (item) => {
       for (var i in item.ClassDetail) {
        let parms2 = [req.userId, item.ClassDetail[i].rollnumber];
        let spRes1 = await _dbContaxt.ExcuteQuery(_dbHelper._StoredProcedureForSubject, parms2)
             if (spRes1 != null && spRes1.length > 0) {
                item.ClassDetail[i].subjectDetail= spRes1.ResData;
             }
       }
 }))
}

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