How to solve the problem of repeated submission of php forms, repeated submission of php forms_PHP tutorial

How to solve the problem of repeated submission of php forms, repeated submission of php forms

Repeated submission is a problem that we often encounter in our development, except that we use js to prevent the duplication of forms Submit, and you can also use php to prevent repeated submissions.

<&#63;php
/*
 * php中如何防止表单的重复提交
 */
session_start();
if (empty($_SESSION['ip'])) {//第一次写入操作，判断是否记录了IP地址，以此知道是否要写入数据库
  $_SESSION['ip'] = $_SERVER['REMOTE_ADDR']; //第一次写入，为后面刷新或后退的判断做个铺垫
  //...........//写入数据库操作
} else {//已经有第一次写入后的操作，也就不再写入数据库
  echo '请不要再次刷新和后退'; //写一些已经写入的提示或其它东西
}
&#63;>

Specific principles
Session scope variable token to prevent.
1. Open session:
session_start();
2. If a form is submitted

 if (isset($token))

Token is included in the form in hidden form.

<input type="hidden" name="token" value="<&#63;php echo $token; &#63;>" />

3. If the form is submitted repeatedly

if ($_SESSION["token"] != $token) { 
  // 不让重复提交，在此处理 
  // header("location:".$_SERVER['PHP_SELF']); 
} else { 
  // 正常的表单提交，在此处理 
  // echo "已提交";  
}

4. Set token value
$token = mt_rand(0,1000000);
2$_SESSION['token'] = $token;

The above is about how to solve the problem of repeated submission of PHP forms. I hope it will be helpful to everyone's learning.