Can't access array values in nodejs

Question

I send an array of values to my node server to be written to a log file.

My $.ajax post works at the client side. At the back-end, I print the array to the console, but when I try to write it to the file using the code below, i get a blank output in the log file.

function log(req,res)
{
  var list = req.body;
  console.log(list);

  for(var i = 0; i < req.body.length; i++)
  fs.writeFileSync("./log.dat", JSON.stringify(list[i]) + "\r\n");
}

The array is a collection of JSON objects like this on the console.

Side Note: I can write to the file if I remove JSON.stringify and [i] though.

Any idea what I'm doing wrong?

Edit:

I did this and I get "undefined" in my log file.

try {
    for(var i = 0; i < 3; i++)
    fs.writeFileSync("./log.dat", list[i] + "\r\n");
} catch (err) {
    console.log('Error writing Metadata.json:' + err.message)
}

I've deduced it's something to do with the loop and the array. I can't reference the array by index.

My ajax req code:

var items = {logs: foghorn_items};
      path = server + "Foghorn/log";
      $.ajax({
      url: path,
      method: 'POST',
      dataType: 'JSON',
      data: items,
      success: function (data){
        alert('Logs sent to file');
      }
);

UPDATE

For some reason the loop doesn't work with list.length and req.body.length.

Sudhakar · Accepted Answer · 2019-09-20 10:03:49Z

2

function log(req,res)
{
  var list = req.body;
  console.log(list);

  for(var i = 0; i < list.logs.length; i++)
  fs.writeFileSync("./log.dat", JSON.stringify(list.logs[i]) + "\r\n");
}

Try the above one

edited Sep 20, 2019 at 10:03

answered Sep 20, 2019 at 9:50

Sudhakar

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11 Comments

Sudhakar Over a year ago

can you show the body data? is that above link in your question?

Shane D'Silva Over a year ago

Yes, that's body data that's getting printed from console.log(list)

Sudhakar Over a year ago

what is printing in console which i have posted?

Sudhakar Over a year ago

what is printing in console now?

ItsMyLife Over a year ago

@ShaneD'Silva what did you get from line console.log(typeof req.body) and console.log(typeof req.body.logs)

|

Roman Panevnyk · Accepted Answer · 2019-09-20 09:34:19Z

1

Use try/catch, to show error:

try {
    fs.writeFileSync("./log.dat", JSON.stringify(list[i]) + "\r\n");
} catch (err) {
    console.log('Error writing Metadata.json:' + err.message)
}

answered Sep 20, 2019 at 9:34

Roman Panevnyk

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3 Comments

Roman Panevnyk Over a year ago

what access rights to the file? and check the path to file

Shane D'Silva Over a year ago

See the last line of my question

Roman Panevnyk Over a year ago

Thought about it, but could not to check it in my side

Kishan Maurya · Accepted Answer · 2019-09-20 09:52:07Z

0

use appendfile method

fs.appendFile("./log.dat", JSON.stringify(list[i]) + "\r\n",function(err){   
});

when you are using writeFileSync, in log file it shows last value written. which might be blank.

answered Sep 20, 2019 at 9:52

Kishan Maurya

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2 Comments

Shane D'Silva Over a year ago

i get "undefined" for list[i]. But if i do console.log(list), it prints all the values

Kishan Maurya Over a year ago

for(var i = 0; i < req.body.length; i++) fs. appendFile("./log.dat", JSON.stringify(req.body[i]) + "\r\n",function(err){ });

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