How to hide empty fieldset, but leave prefix and suffix in place?

Question

Simple as this - I have a Form API fieldset with dynamically changing content. When it's empty, I don't want to show it at all. I use #prefix and #suffix to generate div my AJAX works with.

When I use:

$fieldset['#access'] = FALSE;

it disappears with it's div and no future AJAX call can make it reappear. So, how to hide it with empty, but leave wrapper intact?

Answer 1

The easiest way would be to wrap the fieldset itself in another element.

$fieldset_wrapper = array(
  '#prefix' => '<div class="wrapper">',
  '#suffix' => '</div>',
);

$fieldset_wrapper['fieldset'] = array(
  '#type' => 'fieldset',
  '#access' => FALSE,
);

As you might expect, setting #access to false will prevent an element from being rendered at all.