data replication on page refresh

radian · February 19, 2009

Ok, i have a 3 php scripts. index.php, compose_news.php, list_news.php.

index.php shows the news articles

list_news.php lists all the news articles available in the table

compose_news.php allows you to compose new news articles

This is the problem; i compose a news article, it inserts the data into the table perfectly well, and it shows up in the index and list_news pages fine. But when i refresh the list_news page after using compose_news, it replicates the article i just submitted. This happens everytime i refresh. So if I refresh 10 times, the article will replicate 10 times.

index.php

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" >
   <head>
       <title>Welcome to my site</title>
        <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
        <style type="text/css">
        h1, h3
        {
            text-align:center;
        }
        h3
        {
            background-color:black;
            color:white;
            font-size:0.9em;
            margin-bottom:0px;
        }
        .news p
        {
            background-color:#CCCCCC;
            margin-top:0px;
        }
        .news
        {
            width:70%;
            margin:auto;
        }
        </style>
    </head>
    
    <body>
<h1>Welcome to my site!</h1>
<p>Here are the latest items of news:</p>

<?php
mysql_connect("localhost", "root", "");
mysql_select_db("news");
// We retrieve the 5 latest items of news
$return = mysql_query('SELECT * FROM news ORDER BY id DESC LIMIT 0, 10');
while ($data = mysql_fetch_array($return))
{
?>
<div class="news">
    <h3>
        <?php echo $data['title']; ?>
        <em> - <?php echo date('m/d/Y H\hi', $data['timestamp']); ?></em>
        <?php echo 'written by ' . $data['author']; ?>
    </h3>
    
    <p>
    <?php
    // We delete the potential backslashes THEN we create the HTML enter key pressed (<br />)
    $content = nl2br(stripslashes($data['content']));
    echo $content;
    ?>
    </p>
</div>
<?php
} // End of news loop
?>
<p><a href="list_news.php" />New News</a></p>
</body>
</html>

list_news

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" >
   <head>
       <title>News list</title>
        <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
        <style type="text/css">
        h2, th, td
        {
            text-align:center;
        }
        table
        {
            border-collapse:collapse;
            border:2px solid black;
            margin:auto;
        }
        th, td
        {
            border:1px solid black;
        }
        </style>
    </head>
    
    <body>

<h2><a href="compose_news.php">Add an item of news</a></h2>
<?php
mysql_connect("localhost", "root", "");
mysql_select_db("news");
//-----------------------------------------------------
// Check 1 : do we want to post an item of news?
//-----------------------------------------------------
if (isset($_POST['title']) AND isset($_POST['content']))
{
    $title = addslashes($_POST['title']);
    $content = addslashes($_POST['content']);
    $author = $_POST['author'];
    // We check if it is a news modification or not
    if ($_POST['id_news'] == 0)
    {
        // It is not a modification, we create a new entry in the table
        mysql_query("INSERT INTO news VALUES('', '" . $title . "', '" . $content . "', '" . time() . "', '" . $author . "')");
    }
    else
    {
        // We protect the variable "id_news" to avoid an SQL fault
        $_POST['id_news'] = addslashes($_POST['id_news']);
        // This is a modification, we only update the title and content
        mysql_query("UPDATE news SET title='" . $title . "', content='" . $content . "' WHERE id='" . $_POST['id_news'] . "'");
    }
}

//--------------------------------------------------------
// Check 2 : do we want to delete an item of news ?
//--------------------------------------------------------
if (isset($_GET['delete_news'])) // If we ask to delete an item of news
{
    // Then we delete the corresponding item of news
    // We protect the variable "id_news" to avoid an SQL fault
    $_GET['delete_news'] = addslashes($_GET['delete_news']);
    mysql_query('DELETE FROM news WHERE id=\'' . $_GET['delete_news'] . '\'');
}
?>
<table><tr>
<th>Edit</th>
<th>Delete</th>
<th>Title</th>
<th>Date</th>
<th>Author</th>
</tr>
<?php
$return = mysql_query('SELECT * FROM news ORDER BY id DESC');
while ($data = mysql_fetch_array($return)) // We make a loop to list the items of news
{
?>
<tr>
<td><?php echo '<a href="compose_news.php?edit_news=' . $data['id'] . '">'; ?>Edit</a></td>
<td><?php echo '<a href="list_news.php?delete_news=' . $data['id'] . '">'; ?>Delete</a></td>
<td><?php echo stripslashes($data['title']); ?></td>
<td><?php echo date('m/d/Y', $data['timestamp']); ?></td>
<td><?php echo $data['author'] ?></td>
</tr>
<?php
} // End of loop listing news
?>
</table>
<center><a href="index.php">Home</a></center>
</body>
</html>

compose_news

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" >
   <head>
       <title>Compose an item of news</title>
        <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
        <style type="text/css">
        h3, form
        {
            text-align:center;
        }
        </style>
    </head>
    
    <body>
<h3><a href="list_news.php">Return to the news list</a></h3>
<?php
mysql_connect("localhost", "root", "");
mysql_select_db("news");
if (isset($_GET['edit_news'])) // If you ask to edit a piece of news
{
    // We protect the variable "edit_news" to avoid an SQL fault
    $_GET['edit_news'] = mysql_real_escape_string(htmlspecialchars($_GET['edit_news']));
    // We retrieve the pieces of information of the corresponding item of news
    $return = mysql_query('SELECT * FROM news WHERE id=\'' . $_GET['edit_news'] . '\'');
    $data = mysql_fetch_array($return);
    
    // We place the title and the content in simple variables
    $title = stripslashes($data['title']);
    $content = stripslashes($data['content']);
    $id_news = $data['id']; // This variable is used to remember that this is a modification
}
else // We are composing a fresh item of news
{
    // The variables $title and $content are empty, since it is a fresh item of news
    $title = '';
    $content = '';
    $id_news = 0; // The value of the variable is 0, so we will remember that it is not a modification
}
?>
<form action="list_news.php" method="post">
<p>Title : <input type="text" size="30" name="title" value="<?php echo $title; ?>" /></p>
<p>
    Content :<br />
    <textarea name="content" cols="50" rows="10">
    <?php echo $content; ?>
    </textarea><br />
    
    <input type="hidden" name="id_news" value="<?php echo $id_news; ?>" />
    <input type="hidden" name="author" value="<?php echo $_SESSION["logged"]; ?>" />
    <input type="submit" value="Ok" />
</p>
</form>
</body>
</html>

Cal · February 19, 2009

It's probably because your resending the post data when you refresh, try going on google then going on list_news to see if this is the case.

radian · February 19, 2009

yeah, i submitted a new article and went on google like you said, went back to the list_news and now when i refresh it the article doesn't replicate. yay!

so any way to stop resending of $_POST data?

sasa · February 19, 2009

reorganize your sript that

1st do all database staff (before any output)

2nd after update database use header() to reload page

radian · February 19, 2009

thanks...i'll get working on that

UPDATE: right...it works now, all I did was put the insert SQL query in an insert.php script, before redirecting to list_news.php. Thanks Guys.

Cal · February 19, 2009

yeah, i submitted a new article and went on google like you said, went back to the list_news and now when i refresh it the article doesn't replicate. yay!

so any way to stop resending of $_POST data?

I'm not sure about stopping resending it, but i think most browsers warn the user before they attempt to refresh a page that will resend data.

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data replication on page refresh

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