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Writing data in a text file on server

I am trying to build a simple web page where a user is prompt to click on an image as many times as desired. Eventually, after user is done s/he should click a link saying "I'm done" that should trigger the server to write to disk a sting (let's say: "I clicked x times", which I can manage to get).
I tried:
<a onclick="WriteNGo()" href="next_index.html">I am Done</a>
and of course:
function WriteNGo() {
$.ajax({
type: "POST",
url: 'php/save.php',
data: {writeMe: textToWrite}
});
}
where textToWrite is a global variable that contains the string. I can
alert(textToWrite)
it and get the required sentence.
and added php/save.php at the correct location:
<?php
$data = $_POST['writeMe'];
$f = "../d/data.txt";
file_put_contents($f,$data,FILE_APPEND);
?>
and did a
sudo chmod +777 d
on the folder.
I only want to end up with a text file containing my string, (i.e. "I clicked x times"). I am not even sure that the POST command triggers the PHP server.
One more thing: the index.html is in the root dir, where I am currently running:
php -S localhost:8000
So that there should have not been any problems.
I should also state that there was one time that the string was written, though I can't reproduce this it.

Not sure if this might address your problem. Maybe, try something like this to see, where your data might be written:
<?php
$data = $_POST['writeMe'];
$path = "../d";
$dir = $path . "/";
if (!is_dir($dir)) {mkdir($dir, 0755, true);}
// A faster alternative to file_put_content
$f = $dir . "/data.txt";
$fp = fopen($f, "x+");
fwrite($fp, $data);
fclose($fp);
?>

Server error 500 in PHP

So today I have another small little issue with my PHP, that is causing me to get a server error. You see, I have this javascript function:
$.post('script.php', { limit: str }, function(result) {
console.log(result);
});
which of course makes a call to my php file:
require_once("../data/db-settings.php");
require_once("../data/file.php");
global $pdo;
$list = array();
$limit = $_POST["limit"];
chop($limit, ";");
$stmt = $pdo->prepare("SELECT cust_id, cust_addr FROM project WHERE " . $limit . " = cust_id");
$stmt->execute();
while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
$list[] = $row;
}
echo $list;
The point of the php is to grab some information from a database that a user can dynamically change and use. The issue, I'm assuming, is with how I'm using PDO, because the code I'm using is in working order in another section. I also know that my function call is sending data and working properly, because when I check for just what I send, it sends properly.
Thanks for any help guys.

Check your query FROMproject can not be together.
Your query should look like this:
$pdo->prepare("SELECT cust_id, cust_addr FROM project WHERE " . $limit . " = cust_id");

It is an unobvious error!
So you step by step following the : http://pcsupport.about.com/od/findbyerrormessage/a/500servererror.htm

PDO doesn't throw Internal server error. Must be require_once.
checkout db-settings.php and file.php files. Require_once throws 500 error if it can't find files.
If the paths are correct, then check out included files.
proper way: check your log files.

Javascript variable passed to PHP session in Wordpress

I am not sure if this is the best way to do it, but I have a button that when pressed it call a onClick JS function and it passed two parameters. I want to save those two parameters on a php session, then load another page and use those values.
So, I know that if I use something like this on PAGE !:
<?php
session_start();
$message1 = "A message";
$message2 = "Another message";
$_SESSION['routineName'] = $message1;
$_SESSION['dayName'] = $message2;
?>
I can go to PAGE 2, and by using $_SESSION['routineName'] I can use that info.
So, on PAGE 1 I have that code inside the function that is called with my onClick:
function trackIt(routine, dayName)
{
<?php
session_start();
$message1 = "A message";
$message2 = "Another message";
$_SESSION['routineName'] = $message1;
$_SESSION['dayName'] = $message2;
?>
}
I tried things like:
function trackIt(routine, dayName)
{
<?php
session_start();
$_SESSION['routineName'] = ?> routine; <?php
$_SESSION['dayName'] = $message2;
?>
}
and others, but nothing works.
And this is how I am calling the onClick (trackIt) function:
echo('<td colspan="3" style="background-color:#005673; text-align:right; padding: 4px 0px;">
<button class="btnTrack" onClick="trackIt(\'' . $name . '\' , \'' . $nameday1 . '\')" >Track It!</button></td>');
What I want to do is to save both, routine and dayName, into the session.
Is it possible to save JS variables/parameters into PHP Session?
PS: I am using Wordpress.
Thanks!

The PHP code you put in your files is not executed at Javascript run time, it is executed even before the page gets sent to the client. So you can't access $_SESSION from anywhere within your content, you need to do that from Wordpress's code. Usually this is done via a plugin.
You need to pass your Javascript variables to a server side PHP. As #Grasshopper said, the best (or at least most maintainable way) is through AJAX:
// This is your JAVASCRIPT trackit function
function trackIt(routine, day) {
$.post(
'/wp-setvar.php',
{
routine : routine,
day : day
}, // You can add as many variables as you want (well, within reason)
function success(data) {
// Here we should receive, given the code below, an object
// such that data.result is a string saying "OK".
// Just in case you need to get back something from the server PHP.
// Otherwise just leave this function out.
}
);
};
On the server, you need to create a specific file to accept the incoming variables (it would be best if you did this from a plugin, in order not to add files outside the installation: such practices are frowned upon by security scanners such as WordFence). This here below is a butcher's solution.
<?php /** This is wp-setvar.php */
/** Set up WordPress environment, just in case */
require_once( dirname( __FILE__ ) . '/wp-load.php' );
session_id() || session_start();
nocache_headers();
// DO NOT, FOR ANY REASON, ACCESS DIRECTLY $_SESSION
// ONLY USE A VARIABLE WITHIN $_SESSION (here, "ajjx")
// OTHERWISE THIS MAY ALLOW ANYONE TO TAKE CONTROL OF YOUR INSTALLATION.
$_SESSION['ajjx'] = $_POST;
Header('Content-Type: application/json;charset=utf8');
die(json_encode(array(
'result' => 'OK', // This in case you want to return something to the caller
)));
Now whenever you need the session-saved variable, e.g. "routine", you put
<?php
...
$value = '';
if (array_key_exists('ajjx', $_SESSION)) {
if (array_key_exists('routine', $_SESSION['ajjx']) {
$value = $_SESSION['ajjx']['routine'];
}
}
Or you can define a function in your plugin,
function ajjx($varname, $default = '') {
if (array_key_exists('ajjx', $_SESSION)) {
if (array_key_exists($varname, $_SESSION['ajjx']) {
return $_SESSION['ajjx'][$varname];
}
}
return $default;
}
Then you just:
<?php print ajjx('routine', 'none!'); ?><!-- will print routine, or "none!" -->
or
<?php print ajjx('routine'); ?><!-- will print nothing if routine isn't defined -->
An even more butcherful solution is to add the function definition above within wp-config.php itself. Then it will be available everywhere in Wordpress. Provided you have access to wp-config.php. Also, backup wp-config first and use a full FTP client to do it; do not use a Wordpress plugin to edit it, since if wp-config crashes, the plugin may crash too... and you'll find yourself in a my-can-opener-is-locked-within-a-can situation.
If you don't feel comfortable with some of the above, it's best if you do nothing. Or practice first on an expendable Wordpress installation that you can reinstall easily.

Insert into MySQL database when user clicks on a Link

I am creating a website that has users log in and select a pdf document that they want to download. When they open up the document to view and possibly download, I want data to be logged into a database at the same time.
The code to send the data to the database works (Except for: Undefined index: learningMaterial). But when I want to have the pdf document open and at the same time log the user and other data, all that happens is the document opens up.
Any advice would be appreciated, even for overall better methods of going about what I'm trying to achieve here. Still inexperienced with PHP.
See code below.
HTML
<form name="myform" method='post' action="../includes/writeStats.php">
<input type='hidden' name='learningMaterial' id='learningMaterial' value='learningMaterial'>
<a href='../documents/test.pdf' id='mylink' class='courses' name='Driver Training'> Driver Training </a>
</form>
JS - In header
<script type="text/javascript">
function submitform(){
document.myform.submit(); }
var form = document.getElementById("myform");
document.getElementById("mylink").addEventListener("click", function () {
submitform();
});
</script>
PHP
<?php
$con=mysqli_connect("localhost","root","password","qmptest");
// Check connection
if (mysqli_connect_errno()) {
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
//Get latest log nr
$result = mysqli_query($con,"SELECT * FROM logbook ORDER BY log DESC LIMIT 1");
while($row = mysqli_fetch_array($result)) {
$log = $row['log'] + 1;
//If statement to check if log is 0(first entry) to go here
}
$date = date("Y/m/d");
session_start(); // Start a new session
$person = $_SESSION['currentUser'];
//Not sure if this is correct along with my HTML input
$material = mysqli_real_escape_string($con, $_POST['learningMaterial']);
//Insert into database
$sql="INSERT INTO logbook (log, date, person, learningMaterial)
VALUES ('$log', '$date', '$person', '$material')";
if (!mysqli_query($con,$sql)) {
die('Error: ' . mysqli_error($con));
}
mysqli_close($con);
?>

Your way, clicking the link will override the form being submitted. This leads to the file opening and the form never going through.
Instead, you could try either opening the file in a new window by adding target="_blank" to the tag, or send the files URL through to the PHP, executing the database code then adding to the end:
header("Location: http://yourdomain.com/yourfile.pdf");

Your file is just a normal file being returned by your web server:
<a href='../documents/test.pdf' ...
So while you may be able to suggest to users or browsers that they should invoke some code before downloading this file, you can't actually require it. Any user can just request the file directly. And since PDF files don't execute PHP code (thankfully), your server-side PHP code has no way of knowing that the file has been requested.
What you can do is obscure the file itself behind a PHP request. You can create something like a download.php page which accepts the name of a file (test.pdf) and returns that file.
Be very careful when doing this. Don't just allow users to request any file and blindly return whatever they request. A user can request something like "../../../../../../../../../../etc/passwd" and if your code just builds a path and returns the file then you've just given users a sensitive file. It's best practice to keep a finite known list of identified files (perhaps in a database table) and let users request by the identifier rather than by the file path itself. That way the actual path is only ever known server-side in data that you control.
The main point here, however, is that by using such a page you inject some PHP code in between the user and the file. In order to get the file, the user needs to make a request to a PHP page. On that page you can record the act of the user having requested the file. (As well as perform authorization checks to validate that the user is allowed to view the file, etc.)
Never assume client-side code is going to do what you expect it to do. If you want to ensure something happens for anything approaching security or auditing purposes, it needs to happen in server-side code.

PHP Javascript maintenance page

I used this in my index.php
<?
include('config.php');
if($site->maintenance > 0){
echo "<script>document.location.href='maintenance'</script>";
exit;
}
?>
and in my config.php after checked database connection
$site = mysql_fetch_object(mysql_query("SELECT * FROM problems"));
I made a table in my database and called it problems but even when I put the value 0, it transfers me to maintenance. When I checked the variable $site by var_dump($site) it outputs:
bool(false)
and if I checked it like this: var_dump($site->maintenance) it outputs:
NULL
What do I have to do to manage the maintenance from database and when I want my site to work I change value?

Why you are using JS for this? What if user JS is off? I would use PHP instead
Create a table for maintenance with a column say maintenance_status, now this will hold a boolean value, 0 1... 0 => off, 1 => on, will keep only a single record which will be created once, and later will update it always...
So now later you create this function
function check_maintenance($connection) { /* Call this function on every page,
pass your database connection var
as a function parameter */
$query = mysqli_fetch_array(mysqli_query($connection, "SELECT * FROM tbl_maintenance LIMIT 1"));
/* Limit 1 is optional if you are using only 1 row as I told you,
if you are keeping records of the previous maintenance, probably
you've to sort desc and use limit 1 */
if($query['tbl_maintenance'] == '1') { //Check boolean value, if it's on than redirect
header('Location: maintenance.php'); //Redirect the user to maintenance page
exit;
}
}

The fact that $site is false, could being caused by problem with the query. Change the mysql code to:
$result = mysql_query("SELECT * FROM problems");
if(!$result) {
die(mysql_error();
}
$site = mysql_fetch_object($result);
Further you should learn howto enable error messages in PHP. I guess there are bunch of them. They are disabled by default as it could be a security risk in a production system. But when you are developing you MUST enable them. You can enable it in the php.ini of development system:
php.ini:
...
display_errors=1
...
log_errors=1
...
error_log="/path/to/writable/file"
...
error_reporting=E_ALL
After modifying the php.ini don't forget to restart the web server.