Custom Pagination: $this in "pagination_item_active" function is not in object context?

Question

Joomla 3

I was trying to modify Joomla's pagination output. Following this documentation, I create mytemplate/html/pagination.php file and start modifying it. According to the document, I can write 4 functions in the new pagination file, I actually just want to rewrite _list_render() and _item_active(). However, in libraries/cms/pagination/pagination.php beginning from line 327

    $chromePath = JPATH_THEMES . '/' . $this->app->getTemplate() . '/html/pagination.php';

    if (file_exists($chromePath))
    {
        include_once $chromePath;

        if (function_exists('pagination_item_active') && function_exists('pagination_item_inactive'))
        {
            $itemOverride = true;
        }

        if (function_exists('pagination_list_render'))
        {
            $listOverride = true;
        }
    }

This means I can only get CMS to use my function if only both pagination_item_active() and pagination_item_inactive() exist. But I don't have my own pagination_item_active(), so I copy the content of _item_active() in the CMS's pagination.php to my override file so it looks like this in my pagination.php

......
function pagination_item_active(JPaginationObject $item){
  $title = '';
  $class = '';

  if (!is_numeric($item->text))
  {
    JHtml::_('bootstrap.tooltip');
    $title = ' title="' . $item->text . '"';
    $class = 'hasTooltip ';
  }

  if ($this->app->isAdmin())
  {
    return '<a' . $title . ' href="#" onclick="document.adminForm.' . $this->prefix
    . 'limitstart.value=' . ($item->base > 0 ? $item->base : '0') . '; Joomla.submitform();return false;">' . $item->text . '</a>';
  }
  else
  {
    return '<a' . $title . ' href="' . $item->link . '" class="' . $class . 'pagenav">' . $item->text . '</a>';
  }

}

The problem is, when I run the PHP, I get this error message:

Using $this when not in object context in

/home/w/public_html/templates/rt_photon/html/pagination.php on line 56

What I don't understand is, my pagination.php is supposed to be included into the CMS's one, where there is an "object context", why then is it giving this error message? And how do I overcome this dillema?

Answer 1

The libraries/cms/pagination/pagination.php defines the JPagination class and I don't know exactly how overrides are merged in this class, anyway you could grab a pagination example from protostar default template that, as you see, doesn't use any reference to the main JPagination object and uses only the $item in parameters:

function pagination_item_active(&$item){
    $class = '';

    // Check for "Start" item
    if ($item->text == JText::_('JLIB_HTML_START')){
        $display = '<span class="icon-first"></span>';
    }

    // Check for "Prev" item
    if ($item->text == JText::_('JPREV')){
        $display = '<span class="icon-previous"></span>';
    }

    // Check for "Next" item
    if ($item->text == JText::_('JNEXT')){
        $display = '<span class="icon-next"></span>';
    }

    // Check for "End" item
    if ($item->text == JText::_('JLIB_HTML_END')){
        $display = '<span class="icon-last"></span>';
    }

    // If the display object isn't set already, just render the item with its text
    if (!isset($display)){
        $display = $item->text;
        $class   = ' class="hidden-phone"';
    }

    return '<li' . $class . '><a title="' . $item->text . '" href="' . $item->link . '" class="pagenav">' . $display . '</a></li>';
}

Answer 2

I'm no PHP expert but I'll try to give a small technical reason as to what I believe the issue is in your case.

$this->app->isAdmin() is causing the error because the only object that is being passed through the function is JPagination, which is the $item variable, not $this.

Therefore to get the JApplication object, you'll need to manually define it like so:

$app = JFactory::getApplication();

Then perform your check, like so:

if ($app->isAdmin())
{
    // Your code
}