Delete in multiple POSTS with checkbox

Question

I have already implanted on my site a link to each post that deletes through the ID in the database.

When you click the delete button, the link sends to the 'delete.php' page that executes the command and goes back to the previous page.

I would like to know how I do so that, through the HTML checkbox, I can select several posts and delete them at once?

Follow the posts listing script working:

<form action="deleta.php" method="post">
    <ul class="lista-posts">
        <li class="seleciona"><input type="checkbox" id="checkbox" name="deletar[]" value="<?php echo $row['id']; ?> " /></li>
        <li class="titulo"><?php echo '.$row['titulo'].'; ?></li>
    </ul>
</form> 

DELETA.PHP

if( !empty( $_POST['deletar'] ) ) {
   $groups = array_chunk( $_POST['deletar'], 50 );
   foreach ( $groups AS $group ) {
$group = implode('\',\'', $_POST['deletar']);
        $query = 'DELETE FROM conteudo WHERE id IN (\''. $group .'\')';
       $deleta = mysqli_query($conecta, $query);
      // executa a query
   }    
    if($deleta) {
       header("Location: ".$_SERVER['HTTP_REFERER']."");
       exit;
} else {
    echo mysqli_error($conecta);
}    
} else {
    header("Location: ".$_SERVER['HTTP_REFERER']."");
       exit;
}

Answer 1

Basically your form may have this structure:

<form method="post">
   <input type="checkbox" name="deletar[]" value="1" />Banana<br>
   <input type="checkbox" name="deletar[]" value="2" />Pera<br>
   <input type="checkbox" name="deletar[]" value="3" />Maçã<br>
</form>

Obviously, you will generate the inputs in a loop in PHP, and in value will put the ID of each item to be deleted.

The "secret" here (which is no secret, you have in the PHP documentation) is to put the keys [] in the "name" property, for PHP to receive the data as array

and in PHP just that:

if(!empty($_POST['deletar'])) {
   foreach($_POST['check_list'] as $id) {
      // Aqui voce faz a operacao com o ID desejado
   }
}

Riding the query delete:

To delete, effectively, you can use this syntax depending on the DB:

DELETE FROM minha_tabela WHERE ID IN ( id1, id2, id3, ... );

which can be easily mounted with PHP:

if(!empty($_POST['deletar'])) {
   $query  = 'DELETE FROM minha_tabela WHERE ID IN (';
   $query .= implode( ',', $_POST['deletar'] );
   $query .= ');';
   // executa a query
}

The ideal is that this is optimized in order to group the results in batches, not to become gigantic the IN clause of the query:

if( !empty( $_POST['deletar'] ) ) {
   $groups = array_chunk( $_POST['deletar'], 50 );
   foreach ( $groups AS $group ) {
      $query = 'DELETE FROM minha_tabela WHERE ID IN (' . implode( ',', $group ) . ');';
      // executa a query
   }
}

This way, every 50 records will be executed a query. For consistency, it may be the case to group everything into one transaction, but there already depends on the actual use case, as well as the sanitization of the input values.

Alternatives to other situations:

Nothing prevents you from using other structures, but it would be the case to choose the most suitable for the real case. Here is an "improvised" example of doing otherwise:

<form method="post">
   <input type="checkbox" name="id_1" value="x" />Banana<br>
   <input type="checkbox" name="id_2" value="x" />Pera<br>
   <input type="checkbox" name="id_3" value="x" />Maçã<br>
</form>

and in PHP:

foreach( $listaDeIds as $id ) {
   if( isset( 'id_' . $id ) {
      // Aqui voce faz a operacao com o ID desejado
   }
}

This second way is not suitable for your case because you need to have a list of Ids in advance, I just put as an example that there are several ways to move with the syntax depending on the context.

An example where this syntax would make sense is if instead of a checkbox to delete, you had one radiogroup by item, with options "delete", "archive", "do nothing", for example. But even so, there would be several other ways to solve the same problem.