PHP ask for confirmation before deleting

Question

Hi

In a course I’m doing the person did not teach how to delete a record in the first comics ask for a confirmation before deleting. So I made this code.

<?php
session_start();
header('Content-Type: text/html; charset=utf-8');
include_once("../../controle/conexao.php");
include_once("../../controle/seguranca.php");
$id = $_GET['id'];

$consulta = "SELECT * FROM ordem_producao WHERE op_clientes = '$id'";
$resultado_consulta = mysqli_query($conn, $consulta);   
$row = mysqli_fetch_assoc($resultado_consulta);

if(mysqli_affected_rows($conn) != 0){
        echo "<META HTTP-EQUIV=REFRESH CONTENT = '0;URL=../../paginas/layout/dashboard.php?link=12'>
            <script type=\"text/javascript\">
                alert(\"Este cliente não pode ser apagado, pois existem transações.\");
            </script>"; 
    }else{              
    }?>

My doubt now how I put the message to delete on LSE, and also the code DELETE FROM cadastro_clientes WHERE id='$id';

Thank you

Answer 1

This type of validation is usually done on the client side. You can do it with Javascript in the onclick event of your html tag, which calls your method.

Ex.

<a href="deletar?id=1" onclick="return confirm('Tem certeza que deseja deletar este registro?')">Excluir</a>

Answer 2

Suggestion of how to do

if (mysqli_affected_rows($conn) != 0) {
        echo "<META HTTP-EQUIV=REFRESH CONTENT = '0;URL=../../paginas/layout/dashboard.php?link=12'>
            <script type=\"text/javascript\">
                alert(\"Este cliente não pode ser apagado, pois existem transações.\");
            </script>"; 
}else{

        $sql = "DELETE FROM op_clientes WHERE id = '$id'";
        $executa = mysqli_query($conn, $sql); 

    ?>
        <script type="text/javascript">
        alert(“o cliente foi excluído”);
        </script>
<?php
}
?>

_{note: I refrain from commenting on logistics or security and technical methods. However, I recommend studying the business model and the basics of programming logic and the tools in use. First analyze the business model, if it’s really good what you’re doing (e.g., delete client permanently)}

Answer 3

First of all I want to say that this line in the block of else

</script>";

is wrong and would cause an interpretation error in the code. You had to have put the quote before the first byte '<': "</script>", and would otherwise cause an interpretation error since there is no statement that needs a string (if it were in Javascript, it would be different, "</script>" would be returned on the console, or if it were equal to "use strict" would go the strict way, or ignored; Edit: in PHP the string is ignored). Use echo to play a string in HTML.

---

I understood that you want to display a confirmation box to delete something in the database. In this example I will show the function confirm javascript.

confirm is global, ie is located in the object window. When calling this function -_- the page is locked while the user does not confirm (does not reply) the confirmation box that was opened with the function itself confirm, and once confirmed returns true whether the user’s response was "Yes", or false if the answer was "Cancel", or something like that. Then with this function we can make a condition like if(confirm("Quer me responder?")) alert("Então você quer me responder"); else confirm(":(");, or confirm("Quer me responder?") && alert("Uau! Você é incrível! :D Herói!").

The goal is for the user to answer "yes" to the confirmation box and for something to be removed from a database table. You cannot do this directly from Javascript, so you will have to use AJAX, which will run the file next to the server (the *.php file). It will greatly amplify the answer if I explain about it, but I leave the link of a question answered that will help you.

And another thing, I see no point in using PHP to build the HTML page and run Javascript. To answer your question, try putting this inside your else.

echo '<script>
    if(confirm("Deseja remover o *?")) {
        var xhr = new XMLHttpRequest;
        xhr.get("GET", "delete.php?id='. $id .'", true);

        xhr.onreadystatechange = function() {
            if(this.readyState === 4) {
                if(this.status === 200) {
                    alert("Deletado.");
                }else{
                    /* Erro ao requisicionar o arquivo *.php */
                }
            }
        };

        xhr.send();
    }
</script>';

And the delete.php file should have an id specified in the URL -. -, actually there is the method POST besides the GET. I’m not going to explain that much because the question is a little broad, but let’s see if you understand:

<?php

// se o id foi declarado no URL, e.g: *url*/?id=num
if(isset($_GET['id'])) {
    // pega e converte o id no url para número (caso vier como uma string, mas impossível de acontecer, eu creio)
    $id = intval($_GET['id']);

    // obs: isso é inseguro se você não
    //detectar o usuário que está deletando algo do db
    // remova algo do db usando $id
}

Answer 4

I use the confirmation via javascript, but in this case only to confirm the action, does not make checks. Anyway it is essential to send accidental actions.

onclick="return confirm('Tem certeza que deseja editar este registro?')"