How to validate JSON file upload in Nodejs using jquery

Question

I am reading uploaded json files data but I need to know how can we validate file format or wrong json format data while uploading or after uploading it.

app.post('/upload', function (req, res) {
  let sampleFile;
  if (Object.keys(req.files).length == 0) {
    res.status(400).send('No files were uploaded.');
    return;
  }
 // console.log('req.files >>>', req.files); // eslint-disable-line
  sampleFile = req.files.sampleFile;

  uploadPath = __dirname + '/uploads/' + sampleFile.name;

  sampleFile.mv(uploadPath, function (err) {
    if (err) {
      return res.status(500).send(err);
    }
   // console.log('file', uploadPath);
    let rawdata = fs.readFileSync(uploadPath);
    var student = JSON.parse(rawdata);
    emp = student.employee;
    //console.log(emp);
    res.render('upload.ejs',{emp:emp,uploadPath:uploadPath});
  });
});

I wants to validate json data after uploading it and can I identify JSON objects or json array.

Zeeshan Hassan Memon · Accepted Answer · 2019-07-18 11:14:33Z

1

Possibly trying changing your following code:

let rawdata = fs.readFileSync(uploadPath);
var student = JSON.parse(rawdata);
emp = student.employee;

as:

    let rawdata = fs.readFileSync(uploadPath);
    let student;
    try {
        student = JSON.parse(rawdata);
        emp = student.employee;
    } catch(e) {
        // oops! invalid json found; take possible actions here
    }
    // continue your rest code here

answered Jul 18, 2019 at 11:14

Zeeshan Hassan Memon

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2 Comments

Nagnath Mungade Over a year ago

ok Can i check uploaded data contains objects only or objects array ?

Zeeshan Hassan Memon Over a year ago

you can do Array.isArray(PASS_VAR_HERE) if it returns true it is array else it is not. Please mark answer accepted & upvote, if it helped you in your original question, thanks.

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