将异步数据库的数据导出到csv文件中

Question

I'm currently trying to write results of a sql query into a CSV file using csv-stringify module for NodeJs.

Here is my code :

async exportData() {
        try {
            let request = 'SELECT * FROM PROFACE.dbo.EvenementsMachines WHERE idMachine=215';
            let results = await sql.query(request);

            stringify(results.recordset, {
                    header: true
            }, function (err, output) {
                    fs.writeFile(__dirname+'/results.csv', output, function(err, result) {
                        if (err) {
                            console.log('error : ', err);
                        }
                    });
            })
        } catch (e) {
            console.log(e);
        }
    }

server.app.get("/export", function(req, res) {
    try {
        exportData().then(function(value) {
            res.json("OK");
        });
    } catch (e) {
        console.log(e);
    } 
})

The variable results.recordset looks like that :

            [
              {
                timeStamp: '2020-09-22T05:00:08.230Z',
                compteurTotalPieces: 3899,
                compteurTotalNC: 380
              },
              {
                timeStamp: '2020-09-22T05:02:08.223Z',
                compteurTotalPieces: 21,
                compteurTotalNC: 2
              },
              {
                timeStamp: '2020-09-22T05:04:08.233Z',
                compteurTotalPieces: 43,
                compteurTotalNC: 3
              },
              {
                timeStamp:' 2020-09-22T05:06:08.296Z',
                compteurTotalPieces: 66,
                compteurTotalNC: 4
              },
              {
                timeStamp: '2020-09-22T05:08:08.370Z',
                compteurTotalPieces: 88,
                compteurTotalNC: 5
              },
              {
                timeStamp: '2020-09-22T05:10:08.423Z',
                compteurTotalPieces: 110,
                compteurTotalNC: 6
              },
              {
                timeStamp: '2020-09-22T05:12:08.490Z',
                compteurTotalPieces: 133,
                compteurTotalNC: 7
              },
              {
                timeStamp: '2020-09-22T05:14:08.520Z',
                compteurTotalPieces: 156,
                compteurTotalNC: 9
              }
            ]

This piece of code return the following error.

CsvError: Invalid argument: got {"header":true} at index 1
    at stringify (C:\Users\c.chaulaic\Documents\Dev\mps-prod\node_modules\csv-stringify\lib\index.js:482:13)
    at DAO.exportData (C:\Users\c.chaulaic\Documents\Dev\mps-prod\server\DAO.js:219:4)
    at processTicksAndRejections (internal/process/task_queues.js:93:5) {
  code: 'CSV_INVALID_ARGUMENT'

I guess there is this error because it's asynchrone and the results variable is undefined when I use the stringify() function. But I don't know how to rewrite my code so it can work fine.

Answer 1

Results variable will not be undefined because you are using async function and stringify will call only after you get results. Could you please add how the results variable look for you before you call stringify ?

In additional I would recommend you to define columns option

stringify([{name: '1'}, {name: '2'}], {
    header: true,
    columns: ['name']
  }, function (err, output) {
  });