Category form field type
From Joomla! Documentation
The category form field type provides a drop down list of all published categories for a certain extension. If the parameter has a saved value this is selected when the page is first loaded. If not, the default value (if any) is selected. If the show_root attribute is 1, the first option on the list will be a string representing the root category (which is a translatable string) and is given the value 0.
- type (mandatory) must be category.
- name (mandatory) is the unique name of the parameter.
- label (mandatory) (translatable) is the descriptive title of the field.
- extension (mandatory) is the name of the extension for which the categories will be retrieved. For example, to list content categories, use the value 'com_content'.
- scope (optional) is an alias for extension.
- show_root (optional) is whether a choice representing the root category will be shown.
- default (optional) is the default category ID number.
- description (optional) (translatable) is text that will be shown as a tooltip when the user moves the mouse over the drop-down box.
- class (optional) is a CSS class name for the HTML form field. If omitted this will default to 'inputbox'.
- published (optional) (1/0/2/-2) is whether the drop down will show only published (1), unpublished (0), archived (2) or trashed (-2) categories. It is possible to combine different publishing status by entering the list of the corresponding numbers separated by comma (e.g. "0,2,-2" will display only unpublished, archived and trashed categories in the drop-down).
- multiple (optional) (true/false) is the ability to add more than 1 category to the form field
Implemented by libraries/legacy/form/field/category.php.
Example XML parameter definition:
<field name="mycategory" type="category" extension="com_content" label="Select a category" description="" />