Php fails to open stream even with permissions, restrictions and filesize checked

Question

I'm trying to make php save data on the server. Those data are generated through js script. However, I am unable to make the php create the file. The error msg I get is as follows: Warning: file_put_contents(data/) [function.file-put-contents]: failed to open stream: Is a directory in

I have checked the permissions and the php.ini for restrictions with zero success. Any ideas?

If I change the "data/" bit to "X", the server creates an empty file named X. Which seems strange. The commands used in the js script come from jsPsych.

Thanks a lot!

I append the code:

function saveData(name, data){
  var xhr = new XMLHttpRequest();

  xhr.open('POST', 'write_data.php');
  xhr.setRequestHeader('Content-Type', 'application/json');
  xhr.send(JSON.stringify({filename: name, filedata: data}));
};

(...)

on_finish:

function(){
  saveData('subject-'+subject_id+'.csv', jsPsych.data.get().csv() );
}

<?php

$filename = 'data/'.$_POST['filename'];
$data = $_POST['filedata'];
file_put_contents($filename, $data);

?>

Answer 1

I am not an expert with Xhr & your style of doing it. I do however know jQuery, and regular JS.

Jquery method:

var postName = 'something'; // this is found with $_POST['postName'] in PHP
var postName2 = 'somethingElse'; 
$.post("path/yourFile.php", {postName:value, postName2:value}, function(data){
            if(data == 'success'){
                // complete success 
            } else {
                // assessment failed to save
                console.log(data); 
            }
        });

JS Methods:

The first thing you do, is open up your request...

var xhr= new XMLHttpRequest(); 
xhr.open("POST", "write_data.php", true);

Try this...

xhr.open("POST", "write_data.php", true);

Then you can either use this way of doing it...

xhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xhttp.send("fname=Wubur&lname=Com");

Or the JSON way...

xmlhttp.setRequestHeader("Content-Type", "application/json");
xmlhttp.send(JSON.stringify({fname:"Harry", lname:"Potter"}));

yourFile.php (where we are POSTing to):

If you use the first method (NOT json)...

<?php 

if(isset($_POST['fname']) && isset($_POST['lname']){ // check for post param & permission to create template 
    // do stuff here... 
    echo 'success'; // if everything worked
} else {
    echo 'I need fname and lname!!!'; // no post params supplied 
}

?>

If you use JSON method...

<?php 

$data = json_decode(file_get_contents('php://input'), true);
$data2 = json_decode(file_get_contents('php://input'));
// try both, I forget which one it is...
echo "success";

?>

Answer 2

My guess is $_POST['filename']; is empty. The error:

Warning: file_put_contents(data/) [function.file-put-contents]: failed to open stream: Is a directory

Is self explanatory and even shows data/. Notice the lack of file name after the "/"? Check your incoming post.

More Details

The Super Global $_POST does not have a key filename or that key is empty. This line of code $filename = 'data/'.$_POST['filename']; produces this: data/. So either $_POST['filename'] is empty or it does not exist. Use var_dump or print_r to examine $_POST and see what's in it.

Answer 3

The problem seems to be based around your content type. In PHP, only a Content-Type of application/x-www-form-urlencodedor multipart/form-data populates the $_POST super global array. Since you are telling the server that you are sending the data via application/json, you need to fetch the data from the request body via:

php://input

Try this:

$params = json_decode("php://input", TRUE);
$filename = 'data/'.$params['filename'];
$data = $params['filedata'];
file_put_contents($filename, $data);