Unwanted automatic insertion occurs every time the page is updated in PHP form

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My code has a very strange behavior to perform insertion of unsolicited data from previous data every time the page is updated. Can anyone tell me why?

  • Screen output (Every time the page is updated this message appears and the same repeated insertion happens with the same values).

inserir a descrição da imagem aqui

  • Insertion PHP code (Probably the strange behavior comes from here)
<?php
        require_once '../conexao/conexao.php';  
        if(isset($_POST['Inserir'])){
            $cd_produto = $_POST['cd_produto'];
            $cd_funcionario = $_POST['cd_funcionario'];
            $cd_cliente = $_POST['cd_cliente'];
            $tipo_pagamento = $_POST['tipo_pagamento'];
            $valor_item = $_POST['valor_item'];
            $quantidade = $_POST['quantidade'];
            try{
                $insercao = "INSERT INTO itens_venda (cd_produto,cd_funcionario,cd_cliente,
                tipo_pagamento,valor_item,quantidade,data_venda)
                VALUES (:cd_produto,:cd_funcionario,:cd_cliente,:tipo_pagamento,:valor_item,:quantidade,NOW())";
                $insere_dados = $conexao->prepare($insercao);
                $insere_dados->bindValue(':cd_produto',$cd_produto);
                $insere_dados->bindValue(':cd_funcionario',$cd_funcionario);
                $insere_dados->bindValue(':cd_cliente',$cd_cliente);
                $insere_dados->bindValue(':tipo_pagamento',$tipo_pagamento);
                $insere_dados->bindValue(':valor_item',$valor_item);
                $insere_dados->bindValue(':quantidade',$quantidade);
                $insere_dados->execute();
            } catch (PDOException $falha_insercao) {
                echo "A inserção não foi feita".$falha_insercao->getMessage();
            }
        }
        $seleciona_produto = $conexao->query("SELECT cd_produto, nome FROM produto");
        $resultado_produto = $seleciona_produto->fetchAll();
        $seleciona_funcionario = $conexao->query("SELECT cd_funcionario, nome FROM funcionario");
        $resultado_funcionario = $seleciona_funcionario->fetchAll();
        $seleciona_cliente = $conexao->query("SELECT cd_cliente, nome FROM cliente");
        $resultado_cliente = $seleciona_cliente->fetchAll();        
    ?>
  • Form Code (To help understand)

<!DOCTYPE html>
<html lang="pt-br">
<head>
    <meta charset="utf-8"> 
    <title> Cadastrar venda </title>
</head>
<body>
    <form method="POST">
        <p> Roupa:
            <select name="cd_produto" required="">
                <option value=""></option>
                <?php
                    foreach ($resultado_produto as $v1) {
                        echo "<option value='{$v1['cd_produto']}'>{$v1['nome']}</option>";
                    }
                ?>
            </select>
        </p>
        <p> Funcionário:
            <select name="cd_funcionario" required="">
                <option value=""></option>
                <?php
                    foreach ($resultado_funcionario as $v2) {
                        echo "<option value='{$v2['cd_funcionario']}'>{$v2['nome']}</option>";
                    }
                ?>
            </select>
        </p>
        <p> Cliente:
            <select name="cd_cliente" required="">
                <option value=""> </option>
                <?php
                    foreach ($resultado_cliente as $v3) {
                        echo "<option value='{$v3['cd_cliente']}'>{$v3['nome']}</option>";
                    }
                ?>
            </select>
        </p>
        <p> Pagamento:
            <select name="tipo_pagamento" required="">
                <option value=""> </option>
                <option value="Pagamento á vista">Pagamento á vista</option>
            </select>
        </p>
        <p> Valor do item: <input type="text" name="valor_item" step="0.01" required=""> </p>
        <p> Quantidade: <input type="number" name="quantidade" size=30 required=""> </p>
        <button name="Inserir"> Cadastrar venda </button>
    </form>
</body>
</html>

php mysql

  • The page that you’re looking for used information that you entered. Returning to that page might cause any action that you took to be repeated. Do you want to continue? I just understood that I’m repeating an insertion action several times because of some error that I still don’t know where it is in the code..

  • 1

    When the user asks for a refresh, the browser forwards the last request to get the updated data. Notice what will happen ? Form Ubmit is sent again! One of the ways to solve is to separate your HTML from your PHP, just create a page for example receives.php and put the action of the form pointing to this page, when you finish doing the INSERT redirects to the form page.

  • Another solution might be http://wbruno.com.br/php/diferenciar-refresh-f5-de-postsubmit/

  • So there is no solution to be on the same page?

  • I think not, the solution of the above link is not 100% secure, the Sesssions may expire

1 answer

-1

Are separate things:

First, this page was created with an HTTP request of type POST. Giving Reload on a POST request triggers this browser alert.

According to, this page makes an Insert in the database. Give Reload on the page literally repeats the action, ie creates an INSERT in the database.

The solution is to separate these two things:

  1. Create a script, in a separate URL, that draws the page you want. This page must be accessed by a GET request. (a link or a redirect).

  2. This script that "only draws", when you want to insert the data, calls the unique insertion script (FORM action points to the insertion script). The insertion script, when finished, redirects the browser to the URL that "only draws".

And so, Reload on the page that only draws does not trigger the message, and just draw, do not reinsert the data in the database.

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