These are some addons for the AFC Wordpress plugin http://www.advancedcustomfields.com/

Categories is custom field that generates a drop down field with all the categories from your wordpress site. Unique Key is custom field that generates a unique key for you to use it as a unique number or as a password.

To use it in your theme just copy categories.php and/or unique_key.php in your themes folder or subfolder and in your functions.php paste the following code:

if (function_exists('register_field')) { 
  register_field('Categories_field', dirname(__File__) . '/categories.php'); 
  register_field('Unique_key_field', dirname(__File__) . '/unique_key.php'); 
}

if (function_exists('register_field')) { 
  register_field('Categories_field', dirname(__File__) . '/subfolder_name/categories.php'); 
  register_field('Unique_key_field', dirname(__File__) . '/subfolder_name/unique_key.php');
}

Categories now have two more options

• Show All. When you have the display type to 'drop_down', then it will return 'all'.
  When you have the display type to 'checkboxes' it will return all the categories.


• Show None. When you have the display type to 'drop_down' or 'checkboxes', then it will return 'none'.

Return type: Category Slug

Option: Show Parent

If true, displays Category Parent in a Parent->Child format in admin, in both 'Drop Down' and 'Check Boxes' return type