How can I add a sub-array structure in my results? $_POST

Question

I'm building a form. In that form I have a lot of checkboxes. Normally, It's possible to make an array of some checkboxes (with name attribute).

<input type="text" name="reservatie[0][1]" />
<input type="text" name="reservatie[0][2]" />
<input type="text" name="reservatie[1][1]" />

Normally I would have this result with print_r($_POST);

Array(
    [reservatie] => Array(
        [0] => Array (
            [1] => value
            [2] => value
            )
        )
        [1] => Array
        (
            [1] => value
        )
    )
)

I tried to add the name attribute, but the $_POST takes the structure of $form. But how can I add a sub-array structure in my results?

foreach($result as $time) {
                    $form['reservatie'][$item->id][$time->id] = array(
                          '#type' => 'checkbox',
                          '#return_value' => 1,
                          '#default_value' => 0,
                          '#prefix' => '<td>',
                          '#suffix' => '</td>',
                          '#attributes' => array('name' => 'reservatie[0]['.$time->id.']')          
                    );
                }

This is what I get:

array(42) {
  ["date"]=>
  string(10) "01/07/2016"
  ["reservatie[1][1]"]=>
  int(0)
  ["reservatie[1][2]"]=>
  int(0)
  ["reservatie[1][3]"]=>
  int(0)
  ["reservatie[1][4]"]=>
  int(0)
  ["reservatie[1][5]"]=>
  int(0)
  ["reservatie[1][6]"]=>
  int(0)
  ["reservatie[1][7]"]=>
  int(0)
  ["reservatie[1][8]"]=>
  int(0)
  ["reservatie[1][9]"]=>
  int(0)
  ["reservatie[2][1]"]=>
  int(0)
...
)

Answer 1

I managed to solve my own problem. It was a problem with the #tree. I have to set #tree in the parents to true..

So if you want an array with the following structure:

array {
    ["parent"]=>
     array(4) {
        [1]=>
        array(9) {
          [1]=>
          int(1)
          [2]=>
          int(0)
          [3]=>
          int(0)
          [4]=>
          int(0)
          [5]=>
          int(0)
          [6]=>
          int(0)
          [7]=>
          int(0)
          [8]=>
          int(0)
          [9]=>
          int(0)
        }
    }
}

I had to configure #tree for the parents (2 here), and not only for the children

['parent']['#tree'] = true
['parent'][1]['#tree'] = true

I figured it out after trying and reading https://www.drupal.org/node/48643 (Archived, but it worked for me ;) )