Difference between revisions of "Using JPagination in your component"

From Joomla! Documentation

(Add version tag)
(No difference)

Revision as of 14:32, 8 May 2013

Replacement filing cabinet.png
This Namespace has been archived - Please Do Not Edit or Create Pages in this namespace. Pages contain information for a Joomla! version which is no longer supported. It exists only as a historical reference, will not be improved and its content may be incomplete.
Quill icon.png
Content is Incomplete

This article or section is incomplete, which means it may be lacking information. You are welcome to assist in its completion by editing it as well. If this article or section has not been edited in several days, please consider helping complete the content.
This article was last edited by Tom Hutchison (talk| contribs) 21 months ago. (Purge)

Class Overview

The JPagination class, introduced in Joomla! 1.5, allows developers to reliably and consistently add 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 construct function of the class requires three variables:

  • $total - the total number of items in a list,
  • $limitstart - the offset of the item at which to start, and
  • $limit - the number of items to display per page.

Static Class Methods

	 * Create and return the pagination pages counter string
	 * @access	public
	 * @return	string	Pagination pages counter string
	 * @since	1.5
	function getPagesCounter()

Returns a string containing the current page and total pages as Pagescounter.png

	 * Create and return the pagination result set counter string
	 * @access	public
	 * @return	string	Pagination result set counter string
	 * @since	1.5
	function getResultsCounter()

Returns a string containing the results currently being displayed as Resultscounter.png

	 * Create and return the pagination page list string, ie. Previous, Next, 1 2 3 ... x
	 * @access	public
	 * @return	string	Pagination page list string
	 * @since	1.0
	function getPagesLinks()

Returns an HTML string to display the Pages Links as Pageslinks.png

	 * Return the pagination footer
	 * @access	public
	 * @return	string	Pagination footer
	 * @since	1.0
	function getListFooter()

Returns a combination of the several page-related elements, including: the Display Limit dropdown, the Pages Links and the Pages Counter. Appearance differs in the Front-end and Back-end due to additional CSS formatting applied with the Khepri template.

Front-end: Listfooter-front.png

Back-end: Pagination.png

	 * Creates a dropdown box for selecting how many records to show per page
	 * @access	public
	 * @return	string	The html for the limit # input box
	 * @since	1.0
	function getLimitBox()

Returns an HTML string that will output the Display Limit dropdown as Limitbox.png



with JDatabase

Here is a nice method that uses the strength of mysql who knows pagination too. Really!

Most developers don't use the SQL_CALC_FOUND_ROWS and just double the query without limit. Just don't!! ;-)

$db =& JFactory::getDBO();
$lim	= $mainframe->getUserStateFromRequest("$option.limit", 'limit', 14, 'int'); //I guess getUserStateFromRequest is for session or different reasons
$lim0	= JRequest::getVar('limitstart', 0, '', 'int');
$db->setQuery('SELECT SQL_CALC_FOUND_ROWS x, y, z FROM jos_content WHERE x',$lim0, $lim);
if (empty($rL)) {$jAp->enqueueMessage($db->getErrorMsg(),'error'); return;}	
else {
////Here the beauty starts
$db->setQuery('SELECT FOUND_ROWS();');  //no reloading the query! Just asking for total without limit
$pageNav = new JPagination( $db->loadResult(), $lim0, $lim );
foreach($rL as $r) {
//your display code here
echo $pageNav->getListFooter(  ); //Displays a nice footer


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()
	$mainframe = JFactory::getApplication();
	// Get pagination request variables
	$limit = $mainframe->getUserStateFromRequest('global.list.limit', 'limit', $mainframe->getCfg('list_limit'), 'int');
	$limitstart = JRequest::getVar('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);	
 	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)) {
 	    $this->_pagination = new JPagination($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.

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

Then you have to put another hidden input in your adminform. in your "default.php" add this to form:

  <input type="hidden" name="view" value="your_view_name" />

This is to tell Joomla! to redirect to "your_view_name" view after changing pagination.

Implementing Pagination in Front End

To be able to use Joomla!'s handy JPagination in the front end you need to import Joomla! modellist library into your model first, and extend JModelList class just as you would in the back end

 // import the Joomla modellist library

Then extend the JModelList class

class ComponentnameModelModelName extends JModelList
	 * Method to build an SQL query to load the list data.
	 * @return	string	An SQL query
	protected function getListQuery()
		// Create a new query object.		
		$db = JFactory::getDBO();
		$query = $db->getQuery(true);
		// Select some fields
		// From the tablename
		return $query;

Most of the hard work is already done for you by Joomla!. You only have to extend the above class and add the getListQuery() method that helps you build the query in which the pagination will be based.

Pagination methods, like getPagination(), getItems() & getListFooter() that will be called later from your view are already defined in the parent class of the subclass above.


// import Joomla view library
 * Trainings View
class ComponentNameViewViewName extends JView
	function display($tpl = null) 
		// Get data from the model
		$items = $this->get('Items');
		$pagination = $this->get('Pagination');
		// Check for errors.
		if (count($errors = $this->get('Errors'))) 
			JError::raiseError(500, implode('<br />', $errors));
			return false;
		// Assign data to the view
		$this->items = $items;
		$this->pagination = $pagination;
		// Display the template


Assuming that we are using default template for the view, the following code will generate output with pagination ready in the front end;

// No direct access to this file
defined('_JEXEC') or die('Restricted Access');
// load tooltip behavior
<form action="<?php echo JRoute::_('index.php?option=com_ComponentName'); ?>" method="post" name="adminForm">
<?php echo $this->pagination->getListFooter(); ?>

Remember tor wrap the output in a form.