PHP solution to prevent repeated submission of forms

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Release： 2023-03-23 08:26:01

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PHP+SESSION prevents repeated submission of forms

index.php

The current form page is_submit is set to 0

SESSION_START(); $_SESSION['is_submit'] = 0;

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<form id="reg" action="post.php" method="post">     <p>用户名：<input type="text" class="input" name="username" id="user"></p>     <p>密   码：<input type="password" class="input" name="password" id="pass"></p>     <p>E-mail：<input type="text" class="input" name="email" id="email"></p>     <p><input type="submit" name="submit" class="btn" value="提交注册"/></p> </form>

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post.php

If the form is submitted, set the current 'is_submit to 1, if post.php is refreshed, then the else code will be executed

SESSION_START(); if (isset($_POST['submit'])) {     if ($_SESSION['is_submit'] == '0') {         $_SESSION['is_submit'] = '1';         echo "代码块，要做的事，代码...<a onclick=&#39;history.go(-1);&#39; href=&#39;javascript:void(0)&#39;>返回</a>";     } else {         echo "请不用重复提交<a href=&#39;index.php&#39;>PHP+SESSION防止表单重复提交</a>";     } }

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php Introduction to the implementation method of solving repeated submission of forms

[Introduction] Repeated submission is a problem that we often encounter in development, except We use js to prevent repeated submissions of the form, and we can also use php to prevent repeated submissions. Example 1 The code is as follows Copy code

Repeated submission is a problem we often encounter in development. In addition to using js to prevent repeated submission of forms, we can also use php to prevent repeated submission. .

Example 1

Specific principle

session scope variable token to prevent.

1. Open session:

session_start();

2. If there is a form submission

The code is as follows

Copy code

##< ?php

/*
* How to prevent repeated submission of forms in php
*/
session_start();
if (empty($_SESSION['ip'])) {// For the first write operation, determine whether the IP address is recorded, so as to know whether to write to the database
$_SESSION['ip'] = $_SERVER['REMOTE_ADDR']; //First write, for To pave the way for the subsequent judgment of refreshing or retreating
//...........//Writing to the database operation
} else {//There is already an operation after the first write, It will no longer be written to the database
echo 'Please do not refresh and back off again'; //Write some prompts or other things that have been written
}
?>

The code is as follows	Copy code
if (isset($token))

Token is included in the form in hidden form.

The code is as follows	Copy code
##

3. If the form is submitted repeatedly

The code is as followsCopy code##1.if ($_SESSION["token"] != $token) { 4. Set the token value


2. // Prevent duplicate submission, handle it here 3. // header("location:".$_SERVER['PHP_SELF']); <br>4.} else { <br>5. // Normal form submission, processed here <br>6. // echo "Submitted"; <br>7.}<br><br>

The code is as follows1 .$token = mt_rand(0,1000000);