How to send buffer data in express?

Question

I am trying create and send an excel file to client. Client should download the file via ajax request, because I need filter parameters.

I am using excel4node package to create an excel file.

I write the code below and it's working for now but i am suspicious what if I will have data bigger than buffer. Is this the right way of using buffer? (please check the line with writeToBuffer method)

    const xl = require('excel4node');

    const excelCreator = function (data) {...}

    app.post('/api/excel', jsonParser, (req, res) => {

      let reqObj = {
        method: 'post',
        url: apiUrl + '/MemberService';,
        headers: {
          'Content-Type': 'application/json'
        },
        data: req.body
      };

      axios(reqObj)
        .then(response => {
          res.body = responseHandler(response); // a helper function to set res object

          let data = res.body.Data;

          res.setHeader('Content-Disposition', 'attachment; filename=' + 'excel.xlsx');
          res.type('application/octet-stream');
          res.body.Data = null;

          excelCreator(data).writeToBuffer().then(function (buffer) {
            res.body.Data = buffer;
            res.send(res.body);
          });

        })
        .catch(...);
    });

score 14 · Answer 1 · answered Jan 30 '19 at 18:45

14

First install SheetJS js-xlsx

npm --save install xlsx

Then you can send this response with Express:

const xlsx = require('xlsx')

var wb = xlsx.utils.book_new();

var table = [['a', 'b', 'c'], ['1', '2', '3']]
var ws = xlsx.utils.aoa_to_sheet(table);
xlsx.utils.book_append_sheet(wb, ws, 'test');

// write options
const wopts = { bookType: 'xlsx', bookSST: false, type: 'base64' };
const buffer = xlsx.write(wb, wopts);

res.writeHead(200, [['Content-Type', 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet']]);
res.end(new Buffer(buffer, 'base64'));

Feel free to check the docs https://www.npmjs.com/package/xlsx

answered Jan 30 '19 at 18:45

vmf91

1,897
19
27

1

Thanks for this. I spent just about 3 hours looking into why "binary" response wasn't opening correctly when sent in express. – Han K May 17 '20 at 14:06
3

new Buffer format is deprecated. You can use "res.end(new Buffer(buffer, 'base64'))"; – Narayan Shrestha Aug 19 '20 at 08:43
2

New way to use buffer: https://stackoverflow.com/a/52257416/4435313 – krummens Nov 16 '20 at 23:04

Narayan Shrestha · Answer 2 · 2023-01-17T04:57:30.720

          
           npm install xlsx --save

            import * as XLSX from 'xlsx';

            var json =[
                {
                'Fullname' : "Ram Shrestha",
                'Date Of Birth':"1996-06-01",
                'Gender': "Male",
                'Salary':"80000",
                'Designation':"Senior"
               },
               {
                'Fullname' : "Ramesh Shrestha",
                'Date Of Birth':"1997-06-01",
                'Gender': "Male",
                'Salary':"90000",
                'Designation':"Senior"
              }
           ];

            const fileName = "Sample";

            const workBook: XLSX.WorkBook = XLSX.utils.book_new();
            
            const workSheet: XLSX.WorkSheet = XLSX.utils.json_to_sheet(json);
    
            XLSX.utils.book_append_sheet(workBook, workSheet, `${excelFileName}`)
            const buffer = XLSX.write(workBook, { bookType: 'xlsx', bookSST: false, type: 'base64' });
    
            res.writeHead(200, [
                ['Content-Type', 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'],
                ["Content-Disposition", "attachment; filename=" + `${fileName}.xlsx`]
            ]);
            res.end(Buffer.from(buffer, 'base64'));

hope it works .

How to send buffer data in express?

2 Answers2