[support] D7: hook_field_extra_fields() + field_attach_form()

Hi,

I exposed a field in hook_field_extra_fields():

$form_elements['item_description'] = array( 'label' => t('Item Description'), 'description' => t('Item Description (an extra form field)'), 'weight' => -5, ); $extra_fields['entity_example_basic']['first_example_bundle']['form'] = $form_elements; return $extra_fields;

Now I thought, by calling

field_attach_form('entity_example_basic', $entity, $form, $form_state);

in a form callback, it will be attached to $form automatically. But it doesn't.

Is there a way to change that? Or do I have to add the form field manually in any case?

If I there's no way to attach it automatically - what is the sense in exposing the field in hook_field_extra_fields()?

Cheers,