1 common.inc backdrop_add_tabledrag($table_id, $action, $relationship, $group, $subgroup = NULL, $source = NULL, $hidden = TRUE, $limit = 0)

Assists in adding the tableDrag JavaScript behavior to a themed table.

Draggable tables should be used wherever an outline or list of sortable items needs to be arranged by an end-user. Draggable tables are very flexible and can manipulate the value of form elements placed within individual columns.

To set up a table to use drag and drop in place of weight select-lists or in place of a form that contains parent relationships, the form must be themed into a table. The table must have an ID attribute set. If using theme_table(), the ID may be set as follows:

$output = theme('table', array('header' => $header, 'rows' => $rows, 'attributes' => array('id' => 'my-module-table')));
return $output;

In the theme function for the form, a special class must be added to each form element within the same column, "grouping" them together.

In a situation where a single weight column is being sorted in the table, the classes could be added like this (in the theme function):

$form['my_elements'][$delta]['weight']['#attributes']['class'] = array('my-elements-weight');

Each row of the table must also have a class of "draggable" in order to enable the drag handles:

$row = array(...);
$rows[] = array(
  'data' => $row,
  'class' => array('draggable'),

When tree relationships are present, the two additional classes 'tabledrag-leaf' and 'tabledrag-root' can be used to refine the behavior:

  • Rows with the 'tabledrag-leaf' class cannot have child rows.
  • Rows with the 'tabledrag-root' class cannot be nested under a parent row.

Calling backdrop_add_tabledrag() would then be written as such:

backdrop_add_tabledrag('my-module-table', 'order', 'sibling', 'my-elements-weight');

In a more complex case where there are several groups in one column (such as the block regions on the admin/structure/block page), a separate subgroup class must also be added to differentiate the groups.

$form['my_elements'][$region][$delta]['weight']['#attributes']['class'] = array('my-elements-weight', 'my-elements-weight-' . $region);

$group is still 'my-element-weight', and the additional $subgroup variable will be passed in as 'my-elements-weight-' . $region. This also means that you'll need to call backdrop_add_tabledrag() once for every region added.

foreach ($regions as $region) {
  backdrop_add_tabledrag('my-module-table', 'order', 'sibling', 'my-elements-weight', 'my-elements-weight-' . $region);

In a situation where tree relationships are present, adding multiple subgroups is not necessary, because the table will contain indentations that provide enough information about the sibling and parent relationships. See theme_menu_overview_form() for an example creating a table containing parent relationships.

Note that this function should be called from the theme layer, such as in a .tpl.php file, theme_ function, or in a template_preprocess function, not in a form declaration. Though the same JavaScript could be added to the page using backdrop_add_js() directly, this function helps keep template files clean and readable. It also prevents tabledrag.js from being added twice accidentally.


$table_id: String containing the target table's id attribute. If the table does not have an id, one will need to be set, such as <table id="my-module-table">.

$action: String describing the action to be done on the form item. Either 'match' 'depth', or 'order'. Match is typically used for parent relationships. Order is typically used to set weights on other form elements with the same group. Depth updates the target element with the current indentation.

$relationship: String describing where the $action variable should be performed. Either 'parent', 'sibling', 'group', or 'self'. Parent will only look for fields up the tree. Sibling will look for fields in the same group in rows above and below it. Self affects the dragged row itself. Group affects the dragged row, plus any children below it (the entire dragged group).

$group: A class name applied on all related form elements for this action.

$subgroup: (optional) If the group has several subgroups within it, this string should contain the class name identifying fields in the same subgroup.

$source: (optional) If the $action is 'match', this string should contain the class name identifying what field will be used as the source value when matching the value in $subgroup.

$hidden: (optional) The column containing the field elements may be entirely hidden from view dynamically when the JavaScript is loaded. Set to FALSE if the column should not be hidden.

$limit: (optional) Limit the maximum amount of parenting in this table.

See also




core/includes/common.inc, line 5675
Common functions that many Backdrop modules will need to reference.


function backdrop_add_tabledrag($table_id, $action, $relationship, $group, $subgroup = NULL, $source = NULL, $hidden = TRUE, $limit = 0) {
  $js_added = &backdrop_static(__FUNCTION__, FALSE);
  if (!$js_added) {
    // Add the table drag JavaScript to the page before the module JavaScript
    // to ensure that table drag behaviors are registered before any module
    // uses it.
    backdrop_add_library('system', 'jquery.cookie');
    backdrop_add_js('core/misc/tabledrag.js', array('weight' => -1));
    $js_added = TRUE;

  // If a subgroup or source isn't set, assume it is the same as the group.
  $target = isset($subgroup) ? $subgroup : $group;
  $source = isset($source) ? $source : $target;
  $settings['tableDrag'][$table_id][$group][] = array(
    'target' => $target,
    'source' => $source,
    'relationship' => $relationship,
    'action' => $action,
    'hidden' => $hidden,
    'limit' => $limit,
  backdrop_add_js($settings, 'setting');