System Settings Form and array values

Question

In the following bit of code i am using hook_form_alter to add some more form values to a system_settings_form.

If i add a basic text field, then the variable gets saved, however placing the following items in an array, nothing is getting saved.

I have tried using #tree as specified on the parent container containing the array items.

Sorry for the big code dump, but my math teacher always told me to show my work!

function mymodule_booking_coupons_form_alter(&$form, &$form_state, $form_id, $no_js_use = FALSE) {

  if ($form_id == 'mymodule_booking_ui_admin') {

    $form['coupons'] = array(
      '#type' => 'fieldset', 
      '#title' => t('Coupons'), 
      '#collapsible' => TRUE, 
      '#collapsed' => TRUE,
      '#weight' => 1,
    );

  $form['coupons']['coupon_container'] = [
    '#type' => 'container',
    '#weight' => 80,
    '#tree' => TRUE,
    // Set up the wrapper so that AJAX will be able to replace the fieldset.
    '#prefix' => '<div id="js-ajax-elements-wrapper">',
    '#suffix' => '</div>',
  ];

  $deltas = variable_get('coupon_deltas' , 0);  
  for ($delta = 0; $delta <= $deltas; $delta++) {
    $form['coupons']['coupon_container'][$delta] = [
      '#type' => 'container',
      '#attributes' => [
        'class' => ['container-inline'],
      ],
      '#tree' => TRUE,
    ];
    $form['coupons']['coupon_container'][$delta]['coupon_' . $delta . '_code'] = [
      '#type' => 'textfield',
      '#title' => t('Coupon Code'),
      '#size' => 10,
      '#default_value' => variable_get('coupon_' . $delta . '_code', ''),
    ];
    $form['coupons']['coupon_container'][$delta]['coupon_' . $delta . '_discount'] = [
      '#type' => 'textfield',
      '#title' => t('Discount'),
      '#size' => 10,
      '#default_value' => variable_get('coupon_' . $delta . '_discount', ''),
    ];
    $form['coupons']['coupon_container'][$delta]['coupon_' . $delta . '_type'] = [
      '#type' => 'select',
      '#title' => t('Type'),
      '#options' => array(
            0 => t('Fixed'),
            1 => t('Percentage'),
       ),
      '#default_value' => variable_get('coupon_' . $delta . '_type', 0),
    ];
    $form['coupons']['coupon_container'][$delta]['remove_coupon'] = [
      '#type' => 'submit',
      '#value' => t('x'),
      '#submit' => ['mymodule_booking_coupons_add_more_remove'],
      '#ajax' => [
        'callback' => 'mymodule_booking_coupons_add_more_remove_callback',
        'wrapper' => 'js-ajax-elements-wrapper',
      ],
      '#weight' => 50,
      '#attributes' => [
        'class' => ['button-small'],
      ],
      '#name' => 'remove_coupon_' . $delta,
    ];
  }

  $form['coupons']['coupon_container']['add_name'] = [
    '#type' => 'submit',
    '#value' => t('Add one more'),
    '#submit' => ['mymodule_booking_coupons_add_more_add_one'],
    '#ajax' => [
      'callback' => 'mymodule_booking_coupons_add_more_add_one_callback',
      'wrapper' => 'js-ajax-elements-wrapper',
    ],
    '#weight' => 100,
  ];

  }

}

function mymodule_booking_coupons_add_more_remove($form, &$form_state) {
  $delta_remove = $form_state['triggering_element']['#parents'][1];
  $k = array_search($delta_remove, $form['coupons']['coupon_deltas']);
  unset($form['coupons']['coupon_deltas'][$k]);

  $deltas = variable_get('coupon_deltas' , 1);
  $deltas = $deltas - 1;
  variable_set('coupon_deltas', $deltas);

  $form_state['rebuild'] = TRUE;
  drupal_get_messages();
}

function mymodule_booking_coupons_add_more_remove_callback($form, &$form_state) {
  return $form['coupons']['coupon_container'];
}

function mymodule_booking_coupons_add_more_add_one($form, &$form_state) {
  $deltas = variable_get('coupon_deltas' , 1);
  $deltas = $deltas + 1;
  variable_set('coupon_deltas', $deltas);

  $form_state['rebuild'] = TRUE;
  drupal_get_messages();
}

function mymodule_booking_coupons_add_more_add_one_callback($form, $form_state) {
  return $form['coupons']['coupon_container'];
}

Update: I have placed a dpm($form_state) in the submit handler, and it shows the following array of submitted values - so they make it to this stage, they just dont get saved.

Answer 1

I added my own submit handler and looped through the array saving the values.

foreach ($form_state['values']['coupon_container'] as $delta => $value) {       
        variable_set('coupon_' . $delta . '_code', $form_state['values']['coupon_container'][$delta]['coupon_' . $delta . '_code']);
        variable_set('coupon_' . $delta . '_discount', $form_state['values']['coupon_container'][$delta]['coupon_' . $delta . '_discount']);
        variable_set('coupon_' . $delta . '_type', $form_state['values']['coupon_container'][$delta]['coupon_' . $delta . '_type']);
    }