How custom module chrome works?

Question

I have some trouble with my module chrome.

If I rename the PHP modules.php in template/protostar/html to XXXmodules.php (or anything else, just to break the link), then all the pages on my website are working. But if I leave modules.php as it is, then some pages* are not accessible and I get a This webpage is not available page. On the page that are working, my custom chrome megarounded is working as it should.

The bug also appears if I delete the content of the modules.php or if I only leave:

defined('_JEXEC') or die('Restricted access');

Because I would like to have all the pages on my website accesible + the custom module , I am digging into the way custom chrome works, but except for the question of creating new custom chrome (which I lready know), I can't find any help.

I am trying to understand how protostar/index.php get the link to modules.php so I have tried to look for modules.php in all the files of the folder template/protostar but couldn't any link. I wonder how this modules.php get retrieved! Any idea?

Thanks a lot for your help!

• Strangely the pages that don't work are the ones that don't have a module in there HTML loaded via loadposition or module anywhere from NoNumber. In brief, a page needs at the main article to load a module in order to work.

EDIT: here is the content of my modules.php (but I doubt the error come from there as when I empty the content I still have the error, only renaming modules.php solve the error)

<?php
// no direct access
defined('_JEXEC') or die('Restricted access');

?>
<?php
function modChrome_megarounded($module, &$params, &$attribs)
{ ?>
        <div class="megamod module<?php echo $params->get('moduleclass_sfx'); ?>">
            <div class="megabox">
                <div class="megaboxouter">
                    <div class="megaboxinner">
                        <?php if ($module->showtitle != 0) : ?>
                            <h6><?php echo $module->title; ?></h6>
                        <?php endif; ?>
                    <?php echo $module->content; ?>
                    </div>
                </div>
            </div>
        </div>
    <?php
}
?>

Answer 1

So, modules.php is the way templates get to define (override?) chrome styles if you like. You've probably read about them in the Understanding Overrides article on Joomla Doc's

Without any code, I'm guessing you're probably experiencing a bug in your PHP, the only way for you to check that will be to turn on Joomla's Debug mode and set it's Error Reporting to something like "Developer". The reason it's only breaking on some pages is probably because those pages have modules that use specific chrome styles defined in your template/protostar/html/modules.php.

If you add your modules.php code to the question we can probably help. Given that you say your chrome is working but other pages break, it may be a simple issue that's breaking the PHP interpreter as it processes other styles.

When you disable that file (by renaming etc) the bug is avoided and the default system chrome probably takes over.

In a stock, out of the box Joomla 3.x installation you'll find modules.php files in 6 locations. These are split between the /administrator and the front-end:

1. /administrator/templates/system/html/modules.php
2. /administrator/templates/isis/html/modules.php
3. /administrator/templates/hathor/html/modules.php
4. /templates/system/html/modules.php
5. /templates/beez3/html/modules.php
6. /templates/protostar/html/modules.php

If you look at #1 and #4 you'll see they are in templates/system/html and contain the default chrome. For the front-end, these are html5, table, horz, xhtml, rounded and outline.

When Joomla! tries to render a page, and processes a module position in a template, it calls the renderModule($module, $attribs) method in the JModuleHelper class. e.g like this module position in Protostar:

<div id="aside" class="span3">
    <!-- Begin Right Sidebar -->
    <jdoc:include type="modules" name="position-7" style="well" />
    <!-- End Right Sidebar -->
</div>

That method takes the style attribute of the jdoc token and uses that to build the name of the modChrome_???? method/function that is responsible for the specified style. Using this bit of code:

$chromeMethod = 'modChrome_' . $style;

// Apply chrome and render module
if (function_exists($chromeMethod))
{
    $module->style = $attribs['style'];

    ob_start();
    $chromeMethod($module, $params, $attribs);
    $module->content = ob_get_contents();
    ob_end_clean();
}

As you can see if the function exists in the modules.php file of the current template it will then call that method and capture it's output before returning it to the main rendering process.