Develop Reference

db table not getting updated when forcing logout using ajax

As stated in the title, db table trace_users is not getting updated when no activity happens for 30 mins but its get updated when its 6 mins.
The following code (both JS and PHP) is inside the same php file mno.php.
I am storing the last activity of user through this line let lastActivity = <?php echo time(); ?> ; present in the script below.
<?php
session_start();
if (isset($_GET['action']) && $_GET['action'] == "logout")
{
session_destroy(); // destroy session data in storage
!isset($_SESSION['admin']);
$open = "false";
$write = "0";
$stmt = $connect->prepare("UPDATE trace_users SET open=?, write=? WHERE user_name=?");
$usname = !empty($_SESSION['user_name']) ? $_SESSION['user_name'] : '';
$stmt->bind_param('sss', $open, $write, $usname);
$stmt->execute();
}
?>
<script>
jQuery(document).ready(function($) {
let lastActivity = <?php echo time(); ?> ; // storing last activity of user
let now = <?php echo time(); ?> ;
let logoutAfter = 360;
let timer = setInterval(function() {
now++;
let delta = now - lastActivity;
console.log(delta);
if (delta > logoutAfter) {
clearInterval(timer);
//DO AJAX REQUEST TO close.php
$.ajax({
url: "/abc/mno.php",
type: 'GET',
data: {
action: 'logout'
}, // Line A
success: function(data) {
console.log(data); // Line B
},
error: function(jqXHR, textStatus, errorThrown) {
alert(textStatus);
}
});
}
}, 1000);
});
</script>
Problem Statement:
I am wondering what changes I should make in the code above so that when no activity happens for 30 mins (1800 seconds) then the db table should also get updated.
Case1 (Not Working) : 1800 seconds (page logs out, db doesn't update)
Case2 (Working) : 360 seconds (page logs out, db gets updated)
The values inside session.gc_maxlifetime are 1440(Local Value) 1440(Master Value)
This is what I have tried/debugged:
On the network tab, I am getting Request Method GET when session timeout is set 6 mins and 60 mins.

You need to pass to the javascript some sort of permanent UID that identifies the user even after the session expires.
For the sake of simplification, I'm using user_name that already exists in your code. But you can also assign an UUID for each user, so that one can't guess another user's name and can't modify their stats.
First, you'll pass the $_SESSION['user_name'] from PHP to the JS closure.
let userName = "<?php echo $_SESSION['user_name']; ?>"; // don't forget to wrap the JS string value in quotes or apostrophes
Then, you'll pass it in the AJAX request payload.
data: {
action: 'logout',
user_name: userName // added param
},
Finally, you'll overwrite the value that is sent to DB (if it's sent with the payload)
$usname = !empty($_SESSION['user_name']) ? $_SESSION['user_name'] : ''; // original line
if (isset($_GET['user_name']) && !empty($_GET['user_name'])) {
$usname = $_GET['user_name'];
}
$stmt->bind_param('sss', $open, $write, $usname); // original line
Complete updated code:
<?php
if (isset($_GET['action']) && $_GET['action'] == "logout")
{
session_destroy(); // destroy session data in storage
!isset($_SESSION['pageadmin']);
$open = "false";
$write = "0";
$stmt = $connect->prepare("UPDATE trace_users SET open=?, write=? WHERE user_name=?");
$usname = !empty($_SESSION['user_name']) ? $_SESSION['user_name'] : '';
if (isset($_GET['user_name']) && !empty($_GET['user_name'])) {
$usname = $_GET['user_name'];
}
$stmt->bind_param('sss', $open, $write, $usname);
$stmt->execute();
}
?>
<script>
jQuery(document).ready(function($) {
let lastActivity = <?php echo time(); ?> ; // storing last activity of user
let now = <?php echo time(); ?> ;
let logoutAfter = 10;
let userName = "<?php echo $_SESSION['user_name']; ?>";
let timer = setInterval(function() {
now++;
let delta = now - lastActivity;
console.log(delta);
if (delta > logoutAfter) {
clearInterval(timer);
//DO AJAX REQUEST TO close.php
$.ajax({
url: "/abc/mno.php",
type: 'GET',
data: {
action: 'logout',
user_name: userName
}, // Line A
success: function(data) {
console.log(data); // Line B
},
error: function(jqXHR, textStatus, errorThrown) {
alert(textStatus);
}
});
}
}, 1000);
});
</script>
Few notes at the end:
It's bad practice to combine PHP, HTML and JS altogether in one file.
There are some parts of your code that are not easily reproducible and I had to guess from the context (e.g. i guessed that the session is already set, jQuery is used but there's no <script src="...jquery.js">, there's a DB query but no separate SQL import to try it quickly). Please read and apply the knowledge from How to create a Minimal, Reproducible Example in your next question, so that more people are able or willing to help you with it.

The problem is that you are not changing anything that will prevent the session from expiring after N seconds, you are just coding your script in a way that it will destroy the session after this time. The session gc (garbage colector) executes periodically and deletes old sessions and when that happens, $_SESSION['LAST_ACTIVITY'] will be deleted as well.
You must either try to prevent the gc from deleting sessions or change the logic in your application.

PHP process does not sit indefinitely and does not have program structure as a loop ala Node.js server, which won’t allow you to react to session expiry since it’s not a process that invalidates it, but rather a simple timestamp associated with session that is checked every time you attempt to work with it.
The solution I offer is a simple script that is ran every N minutes to perform a comparison of last user activity timestamp (which, I assume is updated on the request for that user) against expiry period (in you case it is 30 minutes). You can also set session expiry to 30 minutes, though strictly it’s not necessary. If the time difference will exceed 30 minutes, you update the timestamp for the user in your table, and invalidate their session if necessary. The script can be ran through cron or its alternatives and go through all users you require to perform a check.
Do not forget to handle the case when user is logged out on the server but client does not know about it and may continue sending logout requests - raising alert box is rather unclear (it is better to return HTTP Unauthorized code and handle it differently - redirecting to login screen, for example)

There are two things you need to fix.
1). Set the ajax request to be async:false.
$.ajax({
url: "/abc/mno.php",
type: 'GET',
async: false, // <---- ADDED ASYNC FALSE
data: {
action: 'logout'
}, // Line A
success: function(data) {
console.log(data); // Line B
},
error: function(jqXHR, textStatus, errorThrown) {
alert(textStatus);
}
});
2). Destroy the session after performing the SQL Query.
<?php
session_start();
if (isset($_GET['action']) && $_GET['action'] == "logout")
{
!isset($_SESSION['pageadmin']);
$open = "false";
$write = "0";
$stmt = $connect->prepare("UPDATE trace_users SET open=?, write=? WHERE user_name=?");
$usname = !empty($_SESSION['user_name']) ? $_SESSION['user_name'] : '';
$stmt->bind_param('sss', $open, $write, $usname);
$stmt->execute();
session_destroy(); // destroy session data in storage <---- DESTORY AT THE END
}
?>

unable to find $wpdb variable with AJAX call

I'm creating an application in PHP for Wordpress and at this point, I'm trying to fetch a value from a database through AJAX every 2 seconds, and I've created a new file with the function that should be fired.
<?php
global $wpdb;
function conta(){
global $wpdb, $table_name;
$count = $wpdb->get_var("SELECT contatore FROM $table_name WHERE email = '$mail'");
echo "$count";
}
conta()
?>
An this function is called here with an XMLHttpRequest Object every 2 seconds
setInterval(function () {
var url = <?php echo json_encode($con); ?>;
var valuereq = new XMLHttpRequest();
valuereq.open("GET", url, true);
valuereq.send();
valuereq.status;
valuereq.onreadystatechange = function () {
if (valuereq.readyState == 4 && valuereq.status == 200) {
var return_data = valuereq.responseText;
document.getElementById("conta").innerHTML = "Executed: " + return_data;
}
else document.getElementById("conta").innerHTML = "Error";
}
}, 2000);
The Http request is executed correctly, but I receive this error:
Fatal error: Uncaught Error: Call to a member function get_var() on null in
C:\xampp\apps\wordpress\htdocs\wp-content\plugins\bittrex-
trader\admin\partials\conta.php:7 Stack trace: #0
C:\xampp\apps\wordpress\htdocs\wp-content\plugins\bittrex-
trader\admin\partials\conta.php(11): conta() #1 {main} thrown in
C:\xampp\apps\wordpress\htdocs\wp-content\plugins\bittrex-
trader\admin\partials\conta.php on line 7
The program is not able to find the global variable $wpdb, even though is declared. This happens only with the AJAX request because if i include directly the file $wpdb is found and working.
Is there a reason?
Thank you in advance.

Your $mail variable is not set inside the conta() function, yet you perform a query with it.
Use this to load basic wordpress (only loads wordpress core) so you can use $wpbd:
<?php
// use this flag to load only wordpress core
define( 'SHORTINIT', true );
// find the wp-load.php file and require it
require( '/path/to/wp-load.php' );
// now you can use $wpdb
function conta($wpdb, $table_name, $mail)
{
$count = $wpdb->get_var("SELECT `contatore` FROM `".$table_name."` WHERE `email` = '".$mail."'");
echo "$count";
}
// call the function and pass the parameters
conta($wpdb, $table_name, $mail);
// close connection
$wpdb->close();
?>
More on the flag for worpdress core here.

AJAX function for retrieving postgres data not working

I have a simple AJAX function bound to a button that should execute a PostgreSQL query. However, when I click the button that I bound the ajax query to, all I get is the confirmation that the database connection was successful. Nothing seems to happen withe the ajax result (should be printing to console in the handleAjax() function. What am I doing wrong?
This is the javascript code (with jquery):
$(document).ready(function() {
function sendAjax() {
$.ajax({
url: "db/database.php",
success: function (result) {
handleAjax(result);
}
});
}
function handleAjax(result) {
console.log(result);
}
$("#submit-button").on("click", sendAjax);
});
And this it the contents of database.php:
<?php
function dbconn(){
ini_set('display_errors', 1); // Displays errors
//database login info
$host = 'localhost';
$port = 5432;
$dbname = 'sms';
$user = 'postgres';
$password = 'postgres';
// establish connection
$conn = pg_connect("host=$host port=$port dbname=$dbname user=$user password=$password");
if (!$conn) {
echo "Not connected : " . pg_error();
exit;
} else {
echo "Connected.";
}
}
$conn = dbconn();
$sql = "SELECT * FROM numbers;";
$result = pg_query( $sql ) or die('Query Failed: ' .pg_last_error());
$count = 0;
$text = 'error';
while( $row = pg_fetch_array( $result, null, PGSQL_ASSOC ) ) {
$text = $row['message'];
//echo $text;
}
pg_free_result( $result );
?>

The problem is in the database.php file, all you get is "Connected." because you don't print your result at the end. Ajax only receive the output of the php file.
So at the end of your php file you should add :
echo $text;
And you also should remove the echo "Connected.";

AJAX is not a magic wand that in magic way reads PHP code. Let's say AJAX is a user. So what does user do.
Open web page
Wait until PHP execute code and display data
Tells you what he sees
If you don't display anything, ajax can't tell you what he saw.
In thi's place is worth to say that the best way to communicate between PHP and AJAX is using JSON format.
Your code generally is good. All you have to do is to display your data. All your data is in your $text var. So let's convert your array ($text) to JSON.
header('Content-Type: application/json');
echo json_encode($text);
First you set content-type to json, so ajax knows that he reads json. Then you encode (convert) your PHP array to js-friendly format (JSON). Also delete unnecessary echoes like 'Conntected' because as I said, AJAX reads everything what he sees.

You should return $conn from dbconn()
if (!$conn) {
echo "Not connected : " . pg_error();
exit;
} else {
echo "Connected.";
return $conn;
}

XML Parsing Error: no root element found

I am trying to search for all properties in a database that are in one suburb. I have read that it has something to do with the HTML code 204 but I still do not undertand what to do or what it really means. I have not done any JS or PHP in a while so this may be a really silly error but I cannot for the life of me figure it out. Please Help!
Here is my JS code:
function basicSearch(){
//Connect Script to the PHP
var urlLink = "basicSearch.php";
//Get search parameters:
var searchAreaBar = document.getElementById("searchAreaBar").value;
//define the parameters to send to php
var strParameters = "searchAreaBar="+searchAreaBar + "&sid=" + Math.random();
// define the options for the AJAX request
var objOptions = {
// use method post
method: "post",
// use strParameters as the parameters
parameters: strParameters,
// if successfil call fuction(objXHR)
onSuccess: function(objXHR) {
// if objXHR. responseText = yes
if(objXHR.responseText=='Yes'){
alert("Success!");
}
else{
alert("Error! No Properties Found!");
}
}
}
// define the AJAX request object
var objRequest = new Ajax.Request(urlLink,objOptions);
}
Here is my PHP code:
<?php
//Link the username and password:
$connect = mysqli_connect("localhost", "admin", "12345", "realestate") or die ('Connection to database failed: ' . mysql_error());
//Extract variables for request parameters:
extract($_REQUEST);
//Define the query:
$BasicSearch = "SELECT * FROM properties WHERE Suberb='$searchAreaBar'";
//Run the query:
$resDasicSearch = mysqli_query($BasicSearch) or die(mysql_error());
//SET intCount to number of rows in result:
$intCount = mysqli_num_rows($resDasicSearch);
//If intCount is greater than 0:
if($intCount > 0){
//Echo Yes:
echo "Yes";
}
else{
//Echo no:
echo "No";
}
?>
Thanks in advance.

The error was that the browser's compiler was "commenting out" all the php and adding empty HTML tags. It was then getting confused as there was an "empty" document.
This was because the website (including JS, PHP and HTML files) were being stored and run from a local directory. For example:
the URL read:
file:///C:/xampp/htdocs/"Project Name"/Index.html
the correct URL is:
localhost/"Project Name"
IF you are using XAMPP, the folder containing all your project files need to be placed in the htdocs folder in the xampp directory.

As you seem to be using an Ajax function that is not shown it is hard to determine the root cause of the problem because nothing above, as far as I can tell, would yield the error you allude to in the title of the posting - namely "XML Parsing Error: no root element found" - I wonder therefore if there should be a configuration option in Ajax.Request that needs to be set to deal with a basic string response?
That aside you might be able to make use of the following - perhaps even for diagnosis purposes.
<?php
/*
---------------
basicSearch.php
---------------
*/
$dbhost = 'localhost';
$dbuser = 'admin';
$dbpwd = '12345';
$dbname = 'realestate';
$db = new mysqli( $dbhost, $dbuser, $dbpwd, $dbname );
$sql='select * from `properties` where `suberb`=?';
$stmt=$db->prepare( $sql );
if( $stmt ){
$searcharea = $_POST['searchAreaBar'];
$stmt->bind_param( 's', $searcharea );
$stmt->execute();
$stmt->store_result();
$stmt->bind_result( $suberbs );
$stmt->fetch();
echo $stmt->num_rows()==0 ? "No" : "Yes";
}
$stmt->close();
$db->close();
?>
<script>
/* reuseable utility ajax function */
function ajax( method, url, params, callback, options ){
var xhr=new XMLHttpRequest();
xhr.onreadystatechange=function(){
if( xhr.readyState==4 && xhr.status==200 )callback.call( this, xhr.response, options, xhr.getAllResponseHeaders() );
};
var async=params.hasOwnProperty('async') ? params.async : true;
var query=[];
for( var n in params )query.push(n+'='+params[n]);
switch( method.toLowerCase() ){
case 'post': query=query.join('&'); break;
case 'get': url+='?'+query.join('&'); params=null; break;
}
xhr.open( method.toUpperCase(), url, async );
xhr.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
xhr.send( params );
}
/* function that does the search */
function function basicSearch(){
/* configure the parameters to be used in the ajax request */
var method='post';
var url='basicSearch.php';
var params={
searchAreaBar:document.getElementById('searchAreaBar').value,
sid:Math.random()
};
var callback=function(r,o,h){
alert( r ? 'Success' : 'Error! No Properties Found!' )
}
var options={};
/* call the ajax function */
ajax.call(this,method, url, params, callback, options);
}
</script>

Today I meet this error in Firefox's console, that is so simple, while all my API return JSON, one of my API return text/html and it causes Firefox show up that error!
I have changed my NodeJS Express code:
res.end('');
To
res.json({});
ANd it is okay now! Hope it can help someone!

ajax call download fails on chrome works on firefox

Hello I am using spout to run some excel reports. I have a user interface where they input date, model, and other information then I do a GET to send it to a php script where I run a query and then put all the results into an excel file like this:
ini_set('max_execution_time', 600); //300 seconds = 5 minutes
require_once 'spout-2.7.2/src/Spout/Autoloader/autoload.php'; // don't forget to change the path!
use Box\Spout\Reader\ReaderFactory;
use Box\Spout\Writer\WriterFactory;
use Box\Spout\Common\Type;
$reportDate=date("Ymd_hhmmss");
$filename="combined_report".$reportDate.".xlsx";
include ("../log/connectionToDb.php");
$conn = connectionSQL();
//provide error if connection fails
if (!$conn) {
echo "An error occurred.\n";
exit;
}
//connected successfully to db. Do not echo anything otherwise it will not show up on dropdown.
else {
//echo "connected";
}
//From date and to date static in case not provided by user
$fromDate = $_GET['convertedFrom'];
$toDate = $_GET['convertedTo'];
$line= $_GET['selectedLine'];
$model_num=$_GET['modelNumber'];
$writer = WriterFactory::create(Type::XLSX);
ob_start();
$writer->openToBrowser($filename);
$sheet = $writer->getCurrentSheet();
$sheet->setName('Production Data');
$rowCount = 2;
$flag=false;
$production = "query";
//echo memory_get_usage() ;
$result1 = sqlsrv_query($conn, $production);
if($result1 === FALSE){
die(print_r(sqlsrv_errors(), TRUE));
}
do{
if(!$flag) {
$headerRow = ['line', 'Work order','Model number', 'Revision','Serial number','Lpn','Date created','Date completed'];
$writer->addRow($headerRow);
$flag = true;
}
else{
$reportRow = [$row['line'], $row['work_order'], $row['model_num'], $row['revision'],$row['serial_num'],$row['LPN'],$row['date_created'],$row['date_completed']];
$writer->addRow($reportRow);
$rowCount++;
}
}
while ($row = sqlsrv_fetch_array($result1));
$writer->close();
$xlsData = ob_get_contents();
ob_clean();
$response = array(
'op' => 'ok',
'file' => "data:application/vnd.ms-excel;base64,".base64_encode($xlsData)
);
}
die(json_encode($response));
Then on the AJAX call I have the following:
$.ajax({
url: 'modelData/excel-export.php',
method: "GET",
data: {'modelNumber':modelNumber,'convertedFrom':converted_from_UTC,'convertedTo':converted_to_UTC,'selectedLine':selectedLine},
dataType:'json',
success: function(fileCreated){
}
}).done(function(data){
console.log(local);
var $a = $("<a>");
$a.attr("href",data.file);
$("body").append($a);
$a.attr("download","combined_report_"+local+".xlsx");
$a[0].click();
$a.remove();
});
now if I run this in Firefox everything works I am able to download up to 4 months of data which is >60,000 records this has no problem. If I run this in google chrome I cannot download more than 1 week about 20,000 records and U get a "download failed -network error" I was using PHPExcel but then found out it didn't support too many records so I switched to spout but I find the same issue only in google chrome but I don't understand where this limitation is coming from. I have read multiple posts and I have tried setting headers, lengths etc but nothing has worked also I chatted with a spout forum and they said none of the headers were necessary but they were still unable to help me.
I think this question Download failed - network error in google chrome but working in firefox may be going close to the same direction as my issue.
Also I have tried running incognito mode chrome I have tried disabling all extensions
As a side note...The firefox download appears to work fine but we don't "support" firefox so it would be hard for customers to go to multiple browsers specially when they're not tech savy
Any help will be greatly appreciated! :)

I was able to solve this issue by doing the following:
JS
window.open("modelData/excel-export.php?modelNumber="+modelNumber+"&convertedFrom="+converted_from_UTC+"&convertedTo="+converted_to_UTC+"&selectedLine="+selectedLine,
'_blank'// <- This is what makes it open in a new window.
);
then on the PHP side:
ini_set('max_execution_time', 600); //300 seconds = 5 minutes
require_once 'spout-2.7.2/src/Spout/Autoloader/autoload.php'; // don't forget to change the path!
use Box\Spout\Reader\ReaderFactory;
use Box\Spout\Writer\WriterFactory;
use Box\Spout\Common\Type;
$reportDate=date("Ymd_hhmmss");
$filename="combined_report".$reportDate.".xlsx";
include ("../log/connectionToDb.php");
$conn = connectionSQL();
//provide error if connection fails
if (!$conn) {
echo "An error occurred.\n";
exit;
}
//connected successfully to db. Do not echo anything otherwise it will not show up on dropdown.
else {
//echo "connected";
}
//From date and to date static in case not provided by user
$fromDate = $_GET['convertedFrom'];
$toDate = $_GET['convertedTo'];
$line= $_GET['selectedLine'];
$model_num=$_GET['modelNumber'];
$writer = WriterFactory::create(Type::XLSX);
$writer->openToBrowser($filename);
$sheet = $writer->getCurrentSheet();
$sheet->setName('Production Data');
$rowCount = 2;
$flag=false;
$production = "query";
//echo memory_get_usage() ;
$result1 = sqlsrv_query($conn, $production);
if($result1 === FALSE){
die(print_r(sqlsrv_errors(), TRUE));
}
do{
if(!$flag) {
$headerRow = ['line', 'Work order','Model number', 'Revision','Serial number','Lpn','Date created','Date completed'];
$writer->addRow($headerRow);
$flag = true;
}
else{
$reportRow = [$row['line'], $row['work_order'], $row['model_num'], $row['revision'],$row['serial_num'],$row['LPN'],$row['date_created'],$row['date_completed']];
$writer->addRow($reportRow);
$rowCount++;
}
}
while ($row = sqlsrv_fetch_array($result1));
$writer->close();
The library I am using just doesn't work very well with AJAX so this approach solved my issue. Thanks for all the help :)

I used Blob Javascript for the same problem.
this link maybe help someone :
Blob