NodeJS：map函数将返回一个空数组

Question

我尝试使用 mssql npm 使用 mssql 数据库获取结果并将其推送到数组。似乎响应将在 map 函数之外返回一个空数组，非常感谢您的帮助，谢谢。

module.exports = {
 someRouteHandler: async function(req, res, next) {

  const fileStream = await readFileFromS3(req.body.filename); //a function to read file from AWS S3

  if (req.body.productName === "Nike" && type === "Male") {

   const result = await getBrandInformation(req.body, fileStream); //this function will parse data from the file and return object result
   const { brandInformation, brandItems } = result;
   const noneDuplicateArrayContainer = [];
   const duplicateArrayContainer = [];

   for ( const { itemNumber } of brandItems ) {

    let items = await getMatchingList(itemNumber); // will query to database if itemNumber has duplicate or none

    if (items.length > 1) {

     items.map(async({ identifier }) => {
      //if identifier not null query cost
      if (identifier) {
       let cost = await queryCostToDb(identifier); //will query cost from database
       duplicateArrayContainer.push({
        brandItems, identifier, cost
       })
      //if identifier is null no cost to save
      } else {
       duplicateArrayContainer.push({
        brandItems, identifier
       })
      }
     });
    //if items length is not greater than 1 meaning no duplicate
    } else {
     items.map(({ identifier }) => {
      let cost = await queryCostToDb(identifier); //will query cost from database
      noneDuplicateArrayContainer.push({
        brandItems, identifier, cost
       });
     })
    }
   }
   // when sending response noneDuplicateArrayContainer and duplicateArrayContainer  is [ ]
   // in the console, it has data, but response is delay
   return res.status(200).json({ brandInformation, noneDuplicateArrayContainer, duplicateArrayContainer })
  }
 }
}

Answer 1

我已经解决了这个问题，在我的代码中实现了await Promise.all，感谢大家的帮助