Writing data to file using PHP and AJAX not working

Question

I am trying to save json data to a file using AJAX and PHP but the resulting file is empty. Why is it not working?

Here is the HTML:

<!DOCTYPE html>
<html>
<head>
<script src="http://code.jquery.com/jquery-latest.js"></script>
</head>
<body>
<script>

var dataset = {"value1": 2, "value2": 1000};

$.ajax({
   url: 'save.php',
   type: 'POST',
   data: dataset,
   success: function() {
      alert('Success');
   }
});

</script>
</body>
</html>

save.php:

<?php 
$map=json_decode($_POST['json_string']);
$file = "test.json"; 
$fh = fopen($file, 'w') or die("can't open file");
fwrite($fh, $map);
fclose($fh);
?>

$map=json_decode($_POST['json_string']); you didn't post any json_string, nor any JSON to be decoded. type: 'POST' with default settings will send an application/x-www-form-urlencoded POST request with the key->value pairs of your object. — Fabrício Matté
– Fabrício Matté, Commented Sep 21, 2012 at 23:54

Tomasz Kowalczyk · Accepted Answer · 2012-09-21 23:54:17Z

2

You're using wrong POST variable name. Firstly, send your AJAX request with:

data: { 
    json: dataset
    },

And then use:

$map = $_POST['json'];

Don't decode it since you want to save JSON string, not an array. If you want PHP representation, better use var_export():

$map = var_export(json_decode($_POST['json'], true), true);

answered Sep 21, 2012 at 23:54

Tomasz Kowalczyk

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2 Comments

graphmeter Over a year ago

Thank you for the answer! However, still not working. I replaced the AJAX request and the PHP code (using var_export). I get a NULL in the file.

Tomasz Kowalczyk Over a year ago

Do a quick die(var_dump($_POST)); to see what's inside and act accordingly.

Teena Thomas · Accepted Answer · 2012-09-21 23:59:20Z

0

change this line $map=json_decode($_POST['json_string']); to $map=json_decode($_POST['dataset']);

answered Sep 21, 2012 at 23:59

Teena Thomas

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