J1.5:Using JPagination in your component

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Please Note: This page has not been completed and instructions below apply specifically to adding Pagination in the Back-end. Additional instructions for the Front-end will be added soon.

Introduction

The JPagination class, introduced in Joomla! 1.5, allows developers to reliably and consistently adding pagination to the Front-end and Back-end display of their components. The file containing the class can be found at /libraries/joomla/html/pagination.php. The pagination object generates start/end, previous/next, and current page buttons as shown in the image below.

Changes to the Model

Declare $_total and $_pagination variables in the model; these will be returned by the functions getTotal() and getPagination(), respectively.

  /**
   * Items total
   * @var integer
   */
  var $_total = null;

  /**
   * Pagination object
   * @var object
   */
  var $_pagination = null;

Add to or create a __construct() function that will establish values for the $limitstart and $limit variables as these are needed by the JPagination class.

  function __construct()
  {
 	parent::__construct();

	global $mainframe, $option;

	// Get pagination request variables
	$limit = $mainframe->getUserStateFromRequest('global.list.limit', 'limit', $mainframe->getCfg('list_limit'), 'int');
	$limitstart = $mainframe->getUserStateFromRequest($option.'.limitstart', 'limitstart', 0, 'int');

	// In case limit has been changed, adjust it
	$limitstart = ($limit != 0 ? (floor($limitstart / $limit) * $limit) : 0);

	$this->setState('limit', $limit);
	$this->setState('limitstart', $limitstart);
  }

Revise the getData() function, adding the $limitstart and $limit values to the _getList() query. This causes only the needed rows to be returned, rather than all rows.

  function getData() 
  {
 	// if data hasn't already been obtained, load it
 	if (empty($this->_data)) {
 	    $query = $this->_buildQuery();
 	    $this->_data = $this->_getList($query, $this->getState('limitstart'), $this->getState('limit'));	
 	}
 	return $this->_data;
  }

Create a getTotal() function. This function uses the _getListCount() method from JModel to return the total number of rows in the query. The value returned will be used by the getPagination() function.

  function getTotal()
  {
 	// Load the content if it doesn't already exist
 	if (empty($this->_total)) {
 	    $query = $this->_buildQuery();
 	    $this->_total = $this->_getListCount($query);	// _getListCount is from JModel class
 	}
 	return $this->_total;
  }

Create a getPagination() function. The function will create and return a new Pagination object that can be accessed by the View.

  function getPagination()
  {
 	// Load the content if it doesn't already exist
 	if (empty($this->_pagination)) {
 	    jimport('joomla.html.pagination');
 	    $this->_pagination = new JPagination($this->getTotal(), $this->getState('limitstart'), $this->getState('limit') );
 	}
 	return $this->_pagination;
  }

Changes to the View

Revise the View to obtain the pagination object created in the Model and assign it for use in the template.

  ...
  	// Get data from the model
 	$items =& $this->get('Data');	
 	$pagination =& $this->get('Pagination');

	// push data into the template
	$this->assignRef('items', $items);	
	$this->assignRef('pagination', $pagination);
  ...

Changes to the Template

Add a footer area to the display table in the template which holds the pagination object. The method getListFooter() from the JPagination class generates the buttons and their next/previous functionality as shown in the image above. Edit colspan="9" to reflect the number of columns in the table.

  ...
  <tfoot>
    <tr>
      <td colspan="9"><?php echo $this->pagination->getListFooter(); ?></td>
    </tr>
  </tfoot>
  ...