Access callback for blocks

Question

We have "access callback" and "access argument" for defining the access to pages.

What is the way to restrict showing blocks? Can "access callback" also be defined in hook_block_info(), or through any other way?

Answer 1

The array returned from the implementations of hook_block_info() doesn't contain a property equivalent to the access callback for the menus. If you have a module that implements a block, then you can implement hook_block_view() using code that checks if the user has a specific permission. The following code is used from a Drupal module; as you see the block is "rendered" only when the user has the "access content" permission.

case 'recent':
  if (user_access('access content')) {
    $block['subject'] = t('Recent content');
    if ($nodes = node_get_recent(variable_get('node_recent_block_count', 10))) {
      $block['content'] = array(
        '#theme' => 'node_recent_block', 
        '#nodes' => $nodes,
      );
    }
    else {
      $block['content'] = t('No content available.');
    }
  }
  break;

You can use similar code, but checking a different permission, even a custom one your module uses for checking if the user can see the block.

Answer 2

You can also control access to other blocks by implementing hook_block_list_alter(), just remove the blocks which you don't want to be displayed on the current page from the array.

Answer 3

You can add a PHP snippet in the block configuration, and check whether the current user has enough permissions to see the block.