在PHP中提交表单时如何防止多次插入？

问题描述

有时用户可能会按两次 Enter 两次，并且帖子被插入两次。

有没有解决方案除了检查是否已经有一个具有相同标题和内容？

的帖子以外b $ b

解决方案

有几种解决方案可以解决这个问题：

1. 使用Javascript在发布时禁用表单的提交按钮。不足之处在于，这绝对不是一种万无一失的方式。提交表单时不需要真正点击按钮就很容易，对于JavaScript禁用的用户也无效。 我绝对不会推荐这种方法。

    < script language =javascript> 
     function disableSubmitButton（）{
    //您可以填入空格:) 
   } 
     - > 
   < / script> 
   < form action =foo.phpmethod =post> 
   < input type =textname =bar/> 
   < input type =submitvalue =Saveonclick =disableSubmitButton（）;> 
   < / form> 
     




2. 使用将会话变量（例如$ _SESSION ['posttimer']）设置为当前时间戳。在PHP中处理表单，检查$ _SESSION ['posttimer']变量是否存在，并检查某个时间戳差异（IE：2秒）。这样，您可以轻松过滤出双重提交。
   
   

   示例：
   
   

     // form.html 
    < input type =textname =bar/> 
   < input type =submitvalue =Save> 
   < / form> 
    $ b $ // foo.php 
    if（isset（$ _ POST）&&！empty（$ _ POST））
    {
    if（isset（$ _ SESSION ['posttimer']））
    {
    if（（time（） -  $ _SESSION ['posttimer']） {
    //小于2自上次发布后的秒数
   } 
    else 
    {
    //自上次发布后超过2秒
   } 
   } 
    $ _SESSION ['' posttimer'] = time（）; 
    
     




3. 每个POST包含一个唯一标记。 strong>在这种情况下，您还可以为要包含的令牌设置会话变量，然后在窗体中呈现该令牌。表单提交后，您将重新生成令牌。当提交的令牌与会话中的令牌不匹配时，表单已重新提交并应被宣布为无效。

   
   
   

   示例：

     // form.php 
     //显然这可以是任何你想要的，只要它是唯一的
    $ _SESSION ['token'] = md5（session_id（）。time（））; 
   ？> 
   < form action =foo.phpmethod =post> 
   < input type =hiddenname =tokenvalue =<？php echo $ _SESSION ['token']？> /> 
   < input type =textname =bar/> 
   < input type =submitvalue =Save/> 
   < / form> 
    
    foo.php 
    if（isset（$ _ SESSION ['token']））
    {
    if（isset（$ _ POST ['token'] ））
    {
    if（$ _POST ['token']！= $ _SESSION ['token']）
    {
    // double submit 
   } 
    
    
     

Sometimes the user may press Enter twice, and the post is inserted twice.

Is there a solution to prevent this other than check if there is already a post with the same title and content?

解决方案

There are several solutions to this problem:

1. Use Javascript to disable the form's submit button when it is posted. Downside to this is that this is ABSOLUTELY not a foolproof way. It's very easy to submit forms without actually clicking the button, and this would also not work for users with JavaScript disabled. I would definitely not recommend this method.

   Example:

   <script language="javascript">
   <!--
       function disableSubmitButton() {
           // you may fill in the blanks :)
       }
   -->
   </script>
   <form action="foo.php" method="post">
       <input type="text" name="bar" />
       <input type="submit" value="Save" onclick="disableSubmitButton();">
   </form>
   

2. Use PHP sessions to set a session variable (for example $_SESSION['posttimer']) to the current timestamp on post. Before actually processing the form in PHP, check if the $_SESSION['posttimer'] variable exists and check for a certain timestamp difference (IE: 2 seconds). This way, you can easily filter out double submits.

   Example:

   // form.html
   <form action="foo.php" method="post">
       <input type="text" name="bar" />
       <input type="submit" value="Save">
   </form>
   
   // foo.php
   if (isset($_POST) && !empty($_POST))
   {
       if (isset($_SESSION['posttimer']))
       {
           if ( (time() - $_SESSION['posttimer']) <= 2)
           {
               // less then 2 seconds since last post
           }
           else
           {
               // more than 2 seconds since last post
           }
       }
       $_SESSION['posttimer'] = time();
   }
   

3. Include a unique token on each POST. In this case, you would also set a session variable to the token you want to include and then render the token in the form. Once the form is submitted, you re-generate the token. When the submitted token does not match the token in your session, the form has been re-submitted and should be declared invalid.

   Example:

   // form.php
   <?php
       // obviously this can be anything you want, as long as it is unique
       $_SESSION['token'] = md5(session_id() . time());
   ?>
   <form action="foo.php" method="post">
       <input type="hidden" name="token" value="<?php echo $_SESSION['token'] ?>" />
       <input type="text" name="bar" />
       <input type="submit" value="Save" />
   </form>
   
   // foo.php
   if (isset($_SESSION['token']))
   {
       if (isset($_POST['token']))
       {
           if ($_POST['token'] != $_SESSION['token'])
           {
               // double submit
           }
       }
   }
   

这篇关于在PHP中提交表单时如何防止多次插入？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！