Run code only once

Question

Think about this, I’m creating a code "363636". With this code, I’m giving the client the option to type in the input. However, I want this code to be executed only once. That is, when it enters the code in the input, it is over. If it passes this code to someone else using this script it is no longer accepted. The code I did was the following.

I created a variable called $prenchimento, with the coupon code.

$preenchimento = "363636";  // CUPOM

So I created another variable called coupon, where you get the fill variable

$cupom = $preenchimento // NÃO MEXER

In the form, I am picking up the information via $_POST. That is, when the customer enters the coupon he does the check via if. Always checking if the digital value corresponds with the variable $coupon :

    if($tipodeinscricao == $cupom) { 

     echo "Cupom Validade";
}else{

     echo "Cupom não validado";
}

The viable $type registration is the one being picked up from the customer via $_POST. As I said, I need the customer to use this code only once, how can I do that ?

Answer 1

Since using database (which would be more recommended) is not an option, and using cookie would not be good because the cookie is only valid in the browser that created it, and can be deleted, you can use a text file to save the information to the server and do the check.

The file will store the typed code, and you can check if that code exists inside the file.

Create a text file, for example codigos_usados.txt (only one example of a name) on your server. Then enter the code sent by the client (each code sent will be inserted into a new line within the file). The whole code would look like this:

<?php
// essa parte do código no $_POST você disse que já tem
$tipodeinscricao = $_POST['nome_do_campo'];

$preenchimento = "363636";  // CUPOM
$cupom = $preenchimento; // NÃO MEXER

$nome_arquivo = 'codigos_usados.txt'; // nome do arquivo de texto

$valido = false; // crio um flag

if($tipodeinscricao == $cupom) { 

    // aqui eu verifico se o código existe no arquivo
    $arq = file_get_contents($nome_arquivo);

    // o IF abaixo retorna false se o código não existir no arquivo
    if( !preg_match('/'.$tipodeinscricao.'/',$arq) ) {

        // aqui eu gravo o código no arquivo
        $fp = fopen($nome_arquivo,"a");
        $codigo = $tipodeinscricao.PHP_EOL;
        fwrite($fp, $codigo);
        fclose($fp);

        $valido = true; // valido a flag

    }
}

if($valido){
    echo "Cupom Validado";
}else{
    echo "Cupom não validado ou já usado";
}
?>