点击“返回"后，防止重新提交表单按钮 [英] Prevent resubmit form after click "back" button

问题描述

我有2页:

page1.php:
-具有带文本框和提交"按钮的表单.例如:<form name="frm_register" action="page1.php" method="post">

-用于将文本框的值存储到数据库的php和mysql代码.将值提交到数据库后，Javascript会将页面重定向到php2.php.例如:

I have 2 pages :

page1.php :
- has a form with text box and a "submit" button. Eg : <form name="frm_register" action="page1.php" method="post">

- php and mysql code to store the value of textbox to database. Javascript will redirect the page to php2.php after the value is submitted to database. Eg :

$query = "INSERT INTO traceuser (username) VALUES ('{$username}')";
$result = mysql_query($query, $connection);
echo '<script language="javascript">window.location="page2.php";</script>';

page2.php
-mysql从数据库检索数据并显示在此页面上.

page2.php
- mysql retrieve the data from database and display on this page.

问题::当我按后退"按钮时，浏览器将弹出警告消息，提示您将重新提交表单.单击后退"按钮时如何防止重新提交表单?我需要清除page1.php的缓存吗?如何使用php或javascript或ajax做到这一点?

Problem : When I press "back" button, the browser will pop up a warning message saying that the form will be resubmit. How to prevent resubmit the form when click "back" button? Is it I need to clear the cache of page1.php? How to do it with php or javascript or ajax?

---

更新1::感谢您将javascript window.location="page2.php"替换为php header('Location: home2.php');的回答.它解决了80％的问题.其余20％的问题如下所示:

---

Update 1 : Thanks for the answer of replacing javascript window.location="page2.php" to php header('Location: home2.php');. It fix 80% of problem. The rest of 20% problem show below :

    if (strtotime($_SESSION['servertime']) < time()-3){ //10800 = 3 hours 3600 = 1 hour
                if (($username != "") AND ($username != $_SESSION[username])){
                    $_SESSION['servertime'] = $servertime; 
                    $_SESSION['username'] = $username;
                    $query = "INSERT INTO traceuser (username) VALUES ('{$username}')";
                    $result = mysql_query($query20, $connection);
                    header('Location: page2.php');
                    exit;
                } else {
                    echo "same name"; //problem here
                }
            }else{
                echo "submit multiple data too fast"; //problem here too.
            }
   }

执行以下步骤时会发生问题:
1)用户成功提交数据，跳至page2.php查看记录.
2)用户单击返回"按钮，跳回到page1.php.
3)用户提交数据失败，请保留在page1.php上. (因为速度太快或名称相同)
4)用户提交数据成功，跳至page2.php查看记录.
5)用户单击返回"按钮，但浏览器显示警告消息将重新提交表单".

The problem happen when do the following steps :
1) User submit data successfully, jump to page2.php view records.
2) User click "back" button, jump back to page1.php.
3) User submit data fail, stay on page1.php. (because too fast or same name)
4) User submit data successful, jump to page2.php view records.
5) User click "back" button, but browser shows warning message "form will be resubmited".

问题是由于步骤3引起的.步骤3没有运行header('Location: page2.php');，没有跳到page2.php.因此，它导致步骤5显示警告消息.如何解决这个问题?

---

更新2:我已经找到解决20％问题的解决方案，它可以完美运行.我使用session['error123']决定是否要显示错误消息同名".如果成功将数据提交到数据库或成功跳转到page2.php，我将杀死session['error123'].我还使用header('Location: page1.php');重定向到自己的页面(同一页面)，以使该页面以前忘记表单提交.代码示例:

The problem is because of Step 3. Step 3 didn't run header('Location: page2.php');, didn't jump to page2.php. So it cause Step 5 show the warning message. How to fix this problem?

---

Update 2 : I have figured out the solution to fix the 20% problem, it works perfectly. I use session['error123'] to decide whether or not want to display the error message "same name". I kill session['error123'] if success submit data to database or if success jump to page2.php. I also use header('Location: page1.php'); to redirect to own page (same page) to make the page forget about form submission previously. Example of codes :

if ($_SESSION['error123'] == "toofast"){
    echo $_SESSION['error123'] ;
}elseif ($_SESSION['error123'] == "samename"){
    echo $_SESSION['error123'] ;
}

if (strtotime($_SESSION['servertime']) < time()-3){ //10800 = 3 hours 3600 = 1 hour
                if (($username != "") AND ($username != $_SESSION['username'])){
                    $_SESSION['username'] = $username;
                    $query = "INSERT INTO traceuser (username) VALUES ('{$username}')";
                    $result = mysql_query($query20, $connection);
                    $_SESSION['error123'] = "aa";
                    header('Location: http://localhost/plekz/page2.php');
                    exit;
                } else {
                    $_SESSION['error123'] = "samename";
                    header('Location: http://localhost/plekz/page1.php');
                    exit;
                }
            }else{
                $_SESSION['error123'] = "toofast";
                header('Location: http://localhost/plekz/page1.php');
                    exit;
            }
        }
    }

注意:您需要通过<?php ob_start();?>缓冲输出，因为$ _SESSION不能放在header()之前.缓冲区将停止包括会话在内的所有输出，让header()首先发送输出.

Note : You need to buffer the output by <?php ob_start();?> because $_SESSION cannot put before header(). Buffer will stop all output including session, let header() send the output first.

推荐答案

而不是

echo '<script language="javascript">window.location="page2.php";</script>';

提交后，您应该使用header()函数重定向用户.

you should use the header() function to redirect your user after the submission.

所以在伪代码中，

单击page.php上的提交操作page1.php page1.php将数据提交给数据库调用

click submit on page.php action page1.php page1.php submits data to database calls

header('Location: http://example.com/page2.php');

这应该可以防止您的点击后退问题

This should prevent your clicking back problem

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