Node.js 将Excel文件转换为CSV并以JSON格式读取其内容

在我的程序中上载excel文件时，需要将其转换为CSV文件才能读取。该过程工作正常，我使用的是

asyc/await

，但是每当我尝试使用节点中的

csvtojson

包读取文件时，文件都无法正确读取。如果我直接使用CSV文件，那么它工作正常。转换发生时会出现问题

product.js

const multer = require('multer');
const express = require('express');
const router = express.Router();
const csv = require('csvtojson');
const fs = require('fs');
const xlsx = require('node-xlsx');

router.post('/upload', upload.single('singleFile'), async (req, res) => {
    let csvFilePath = req.file.path;
    let fileType = req.file.mimetype;

    const convertToCSV = async _ => {
        console.log("2");
        if (fileType === 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet' ||
            fileType === 'application/vnd.ms-excel') {
            let obj = xlsx.parse(csvFilePath);
            let rows = [];
            let writeStr = "";

            for (let i = 0; i < obj.length; i++) {
                let sheet = obj[i];
                for (let j = 0; j < sheet['data'].length; j++) {
                    rows.push(sheet['data'][j]);
                }
            }

            //creates the csv string to write it to a file
            for (let i = 0; i < rows.length; i++) {
                writeStr += rows[i].join(",") + "\n";
            }

            console.log("3");
            fs.writeFile("csv/out.csv", writeStr, function (err) {
                if (err) {
                    return res.status(400).send({'error': err});
                }
                console.log("4");
                console.log("out.csv was saved in the current directory!");
            });
        }
    }
    console.log("1");
    await convertToCSV().then(async _ => {
        console.log("5");
        const jsonArray = await csv({flatKeys: true})
            .fromFile(csvFilePath)
            .then(async (jsonObj) => {
                console.log("6");
                console.log(jsonObj[0]);
                ...
                
                //Few more functions
                
            }).catch(err => {
                return res.status(400).send(err);
            });
    });
});

然而，如果上载了新的CSV文件或使用了现有的CSV文件，则

console.log（jsonObj[0]）的输出是

{
  'Column1': 'Column 1 Data',
  field2: 'field2 Data',
  field3: 'field 3 Data',
  Categories: 'categories',
  ....
}

我在
fs.writeFile
之前添加了
wait
，但同样的问题也出现了。有两个文件保存在目录
csv/

c33129f3bdef482657992dbf452d2c1b
out.csv

并且读取上一个文件的内容（假设它们非常相似），并且不读取
out.csv

更新

围绕
fs.writeFile
包装了一个承诺，控制台现在已订购，但是数据读取的输出仍然相同：

 const convertToCSV = async _ => {
        return new Promise(((resolve, reject) => {
            console.log("2");
            ....

                console.log("3");
                fs.writeFile("csv/out.csv", writeStr, function (err) {
                    if (err) {
                        return res.status(400).send({'error': err});
                    }
                    console.log("4");
                    console.log("out.csv was saved in the current directory!");
                    resolve();
                });
            }
        }));
    }

控制台日志

1
2
3
4
out.csv was saved in the current directory!
5
6
{
  'PK\u0003\u0004\u0014\u0000\u0006\u0000\b\u0000\u0000\u0000!\u0000b�h^\u0001\u0000\u0000�\u0004\u0000\u0000\u0013\u0000\b\u0002[Content_Types].xml �\u0004\u0002(�\u0000\u0002\u0000\u0000\
u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u00

您不必等待fs.writeFile（“csv/out.csv”

，这就是为什么您在console中获得

5

之后才获得

4

。 您应该将函数内容包装成承诺：

const convertToCSV = async _ => {
  return new Promise((resolve, reject) => {
     console.log("2");
     ...
     console.log("3");
     fs.writeFile("csv/out.csv", writeStr, function (err) {
        if (err) {
          // I'd prefer to call "reject" here and add try/catch outside for sending 400
          return resolve(res.status(400).send({'error': err}));
        }
        console.log("4");
        console.log("out.csv was saved in the current directory!");
        resolve();
     });
  })
)

您还可以读取包含Excel文件名的

csvFilePath

，而不是存储在

CSV/out.CSV

名称下的CSV

const convertToCSV = async _ => {
  return new Promise((resolve, reject) => {
     console.log("2");
     ...
     console.log("3");
     fs.writeFile("csv/out.csv", writeStr, function (err) {
        if (err) {
          // I'd prefer to call "reject" here and add try/catch outside for sending 400
          return resolve(res.status(400).send({'error': err}));
        }
        console.log("4");
        console.log("out.csv was saved in the current directory!");
        resolve();
     });
  })
)