CODEWITHSUNDEEP
node.jsexpresspost
ccm
ccm

Reputation: 25

download empty file in express

I'm new to node.js, can anyone help me with my code. the code below can write the query result into 'public/out.csv' file on the server end, but it downloads an empty into the client end. I have no cue why is that.

function ouputCSV(data, filename){
   return new Promise(function(resolve, reject){
   console.log('writes the results into csv file');
   const ws = fs.createWriteStream('public/'+filename+'.csv');
   fastcsv.write(data, {headers: true, delimiter:'\t'})
          .pipe(ws);
   var filepath = ws.path;
   resolve(filepath);
})

con.query(sql, function(err, result){
   if (err) throw err;

   var filename = ('out');
   var promise = ouputCSV(result,filename);

   promise.then(function(file){
      res.download(file);
   })
})

Upvotes: 0

Views: 590

Answers (1)

Aritra Chakraborty
Aritra Chakraborty

Reputation: 12542

if fastcsv is a stream then you need to wait for it to write to your file completely then resolve it.

according to fast-csv documentation you can do this:

const rows = [
    [ 'a', 'b' ],
    [ 'a1', 'b1' ],
    [ 'a2', 'b2' ],
];
csv.writeToPath(path.resolve(filepath), rows)
    .on('error', err => console.error(err))
    .on('finish', () => {
                          console.log('Done writing.')
                           resolve(filepath);
                         });

Or you can resolve on end event.

fastcsv.write(data, {headers: true, delimiter:'\t'})
      .pipe(ws);
var filepath = ws.path;
fastcsv.on('end', ()=> resolve(filepath));

Upvotes: 1

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