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php - Best way to avoid the submit due to a refresh of the page

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I think that this problem occurs often on a web application development. But I'll try to explain in details my problem.

I'd like to know how to correct this behavior, for example, when I have a block of code like this :

<?
    if (isset($_POST['name'])) {
        ... operation on database, like to insert $_POST['name'] in a table ...
        echo "Operation Done";
        die();
    }

?>

<form action='page.php' method='post' name="myForm">
    <input type="text" maxlength="50" name="name" class="input400" />
    <input type="submit" name="Submit" />
</form>

When the form gets submitted, the data get inserted into the database, and the message Operation Done is produced. Then, if I refreshed the page, the data would get inserted into the database again.

How this problem can be avoided? Any suggestion will be appreciated :)

Undefined asked

2022-06-21

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Answer

Solution:

Don't show the response after your create action; redirect to another page after the action completes instead. If someone refreshes, they're refreshing the GET requested page you redirected to.

// submit
// set success flash message (you are using a framework, right?)
header('Location: /path/to/record');
exit;

Undefined answered · Answer 2 · 2022-06-21

Answer

Solution:

Set a random number in a session when the form is displayed, and also put that number in a hidden field. If the posted number and the session number match, delete the session, run the query; if they don't, redisplay the form, and generate a new session number. This is the basic idea of XSRF tokens, you can read more about them, and their uses for security here: http://en.wikipedia.org/wiki/Cross-site_request_forgery

Here is an example:

<?php
session_start();

if (isset($_POST['formid']) && isset($_SESSION['formid']) && $_POST["formid"] == $_SESSION["formid"])
{
    $_SESSION["formid"] = '';
    echo 'Process form';
}
else
{
    $_SESSION["formid"] = md5(rand(0,10000000));
?>
    <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post">
    <input type="hidden" name="formid" value="<?php echo htmlspecialchars($_SESSION["formid"]); ?>" />
    <input type="submit" name="submit" />
</form>
<?php } ?>

Undefined answered · Answer 3 · 2022-06-21

Answer

Solution:

I ran into a similar problem. I need to show the user the result of the POST. I don't want to use sessions and I don't want to redirect with the result in the URL (it's kinda secure, I don't want it accidentally bookmarked). I found a pretty simple solution that should work for the cases mentioned in other answers.

On successfully submitting the form, include this bit of Javascript on the page:

<script>history.pushState({}, "", "")</script>

It pushes the current URL onto the history stack. Since this is a new item in history, refreshing won't re-POST.

UPDATE: This doesn't work in Safari. It's a known bug. But since it was originally reported in 2017, it may not be fixed soon. I've tried a few things (replaceState, etc), but haven't found a workaround in Safari. Here are some pertinent links regarding the issue:

Undefined answered · Answer 4 · 2022-06-21

Answer

Solution:

Like this:

<?php
if(isset($_POST['uniqid']) AND $_POST['uniqid'] == $_SESSION['uniqid']){
    // can't submit again
}
else{
    // submit!
    $_SESSION['uniqid'] = $_POST['uniqid'];
}
?>

<form action="page.php" method="post" name="myForm">
    <input type="hidden" name="uniqid" value="<?php echo uniqid();?>" />
    <!-- the rest of the fields here -->
</form>

Undefined answered · Answer 5 · 2022-06-21

Answer

Solution:

I think it is simpler,

page.php

<?php
   session_start();
   if (isset($_POST['name'])) {
        ... operation on database, like to insert $_POST['name'] in a table ...
        $_SESSION["message"]="Operation Done";
        header("Location:page.php");
        exit;
    }
?>

<html>
<body>
<div style='some styles'>
<?php
//message here
echo $_SESSION["message"];
?>
</div>
<form action='page.php' method='post'>
<!--elements-->
</form>
</body>
</html>

Undefined answered · Answer 6 · 2022-06-21

Answer

Solution:

So, for what I needed this is what works.

Based on all of the above solutions this allows me to go from a form to another form, and to the n^ form , all the while preventing the same exact data from being "saved" over and over when a page is refreshed (and the post data from before lingers onto the new page).

Thanks to those who posted their solution which quickly led me to my own.

<?php
//Check if there was a post
if ($_POST) {
//Assuming there was a post, was it identical as the last time?
   if (isset($_SESSION['pastData']) AND $_SESSION['pastData'] != $_POST) {
//No, Save
   } else {
//Yes, Don't save
   }
} else {
//Save
}
//Set the session to the most current post.
$_session['pastData'] = $_POST;
?>

Undefined answered · Answer 7 · 2022-06-21

Answer

Solution:

We work on web apps where we design number of php forms. It is heck to write another page to get the data and submit it for each and every form. To avoid re-submission, in every table we created a 'random_check' field which is marked as 'Unique'.

On page loading generate a random value and store it in a text field (which is obviously hidden).

On SUBMIT save this random text value in 'random_check' field in your table. In case of re-submission query will through error because it can't insert the duplicate value.

After that you can display the error like

if ( !$result ) {
        die( '<script>alertify.alert("Error while saving data OR you are resubmitting the form.");</script>' );
}

Undefined answered · Answer 8 · 2022-06-21

Answer

Solution:

No need to redirect...

replacedie(); with

isset(! $_POST['name']);

, setting the isset to isset not equal to $_POST['name'], so when you refresh it, it would not add anymore to your database, unless you click the submit button again.

<?
    if (isset($_POST['name'])) {
        ... operation on database, like to insert $_POST['name'] in a table ...
        echo "Operation Done";
        isset(! $_POST['name']);
    }

?>

<form action='page.php' method='post' name="myForm">
    <input type="text" maxlength="50" name="name" class="input400" />
    <input type="submit" name="Submit" />
</form>

Undefined answered · Answer 9 · 2022-06-21

Answer

Solution:

This happen because of simply on refresh it will submit your request again.

So the idea to solve this issue by cure its root of cause.

I mean we can set up one session variable inside the form and check it when update.

if($_SESSION["csrf_token"] == $_POST['csrf_token'] )
{
// submit data  
}

//inside from 

$_SESSION["csrf_token"] = md5(rand(0,10000000)).time(); 

<input type="hidden" name="csrf_token" value=" 
htmlspecialchars($_SESSION["csrf_token"]);">

Undefined answered · Answer 10 · 2022-06-21

Answer

Solution:

I think following is the better way to avoid resubmit or refresh the page.

$sample = $_POST['submit'];
if ($sample == "true") 
 {
//do it your code here
$sample = "false";
 }

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