Workaround for PHP to prevent forms from repeating submissions

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Php+session prevent forms from repeating commits

index.php

Current form page Is_submit set to 0

Session_Start (); $_session[' is_submit '] = 0;

<form id= "Reg" action= "post.php" method= "POST" >     <p> User name: <input type= "text" class= "input" name= " Username "id=" user "></p>     <p> Secret &nbsp; code: <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= "Submit Registration"/></p> </form>

post.php

If the form is submitted, the current ' is_submit is 1, if the 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 "code block, what to do, code ... <a onclick= ' history.go ( -1); ' href= ' javascript:void (0) ' > Return </a>";     } else {         echo "Please do not repeat submit <a href= ' index.php ' >php+session prevent form duplicate submission </a>";     }}

Introduction to PHP to resolve form repeating commit implementation method

[Guide] Repeated submissions are often encountered in our development of a problem, in addition to our use of JS to prevent the form of repeated submissions, but also can use PHP to prevent duplicate submissions Oh. Example 1 code below to copy code

Repeating commits is a common problem in our development, in addition to the use of JS to prevent the form of repeated submissions, but also can use PHP to prevent duplicate submissions Oh.

code as follows

copy code

<?php /* * How to prevent duplicate submissions of forms in PHP */ Session_Start (); if (Empty ($_session[' IP '))) {//First write operation, determine whether the IP address is logged, to know whether to write to the database $_session[' IP '] = $_server[' remote_addr ']; The first write, for the back of the decision to refresh or back to make a cushion //...........//write to the database operation } else {//already have the first write operation, will no longer write to the database Echo ' Please do not refresh and back again '; Write some hints or other things that have been written } ?

Specific principles

Session range variable token to prevent.

1. Open session:

Session_Start ();

2. If a form is submitted

The code is as follows	Copy Code
if (Isset ($token))

Tokens are included in the form as hidden.

The code is as follows	Copy Code
<input type= "hidden" name= "token" value= "<?php echo $token;?>"/>

3. If you are submitting a form repeatedly

The code is as follows	Copy Code
1.if ($_session["token"]! = $token) { 2.//Do not allow duplicate submissions, this processing 3.//Header ("Location:". $_server[' php_self '); 4.} else { 5.//Normal form submission, here processing 6.//echo "submitted"; 7.}

4. Set the token value

The code is as follows	Copy Code
1. $token = Mt_rand (0,1000000); 2.$_session[' token '] = $token;

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