Regression 3.7: last template style preview not working

[joeforjoomla]

Steps to reproduce the issue

Install a new template on Joomla 3.7

Try to open the preview using the URL such as:
http://joomla37/?template=mytemplate

Expected result

The frontend uses the latest installed template named 'mytemplate'

Actual result

The default template is still used

System information (as much as possible)

The code change in site.php included in the function 'getTemplate' caused the regression.

Working code on Joomla 3.6.5:

if (!$templates = $cache->get('templates0' . $tag))
		{
			// Load styles
			$db = JFactory::getDbo();
			$query = $db->getQuery(true)
				->select('id, home, template, s.params')
				->from('#__template_styles as s')
				->where('s.client_id = 0')
				->where('e.enabled = 1')
				->join('LEFT', '#__extensions as e ON e.element=s.template AND e.type=' . $db->quote('template') . ' AND e.client_id=s.client_id');

			$db->setQuery($query);
			$templates = $db->loadObjectList('id');

			foreach ($templates as &$template)
			{
				$registry = new Registry;
				$registry->loadString($template->params);
				$template->params = $registry;

				// Create home element
				if ($template->home == 1 && !isset($templates[0]) || $this->_language_filter && $template->home == $tag)
				{
					$templates[0] = clone $template;
				}
			}

			$cache->store($templates, 'templates0' . $tag);
		}

		if (isset($templates[$id]))
		{
			$template = $templates[$id];
		}
		else
		{
			$template = $templates[0];
		}

Regression code on Joomla 3.7, the 'by reference' variable $template is overwritten in the final $template = $templates[0]; so the latest template style is lost in the $templates array.

if ($cache->contains($cacheId))
		{
			$templates = $cache->get($cacheId);
		}
		else
		{
			// Load styles
			$db = JFactory::getDbo();
			$query = $db->getQuery(true)
				->select('id, home, template, s.params')
				->from('#__template_styles as s')
				->where('s.client_id = 0')
				->where('e.enabled = 1')
				->join('LEFT', '#__extensions as e ON e.element=s.template AND e.type=' . $db->quote('template') . ' AND e.client_id=s.client_id');

			$db->setQuery($query);
			$templates = $db->loadObjectList('id');

			foreach ($templates as &$template)
			{
				// Create home element
				if ($template->home == 1 && !isset($template_home) || $this->_language_filter && $template->home == $tag)
				{
					$template_home = clone $template;
				}

				$template->params = new Registry($template->params);
			}

			// Add home element, after loop to avoid double execution
			if (isset($template_home))
			{
				$template_home->params = new Registry($template_home->params);
				$templates[0] = $template_home;
			}

			$cache->store($templates, $cacheId);
		}

		if (isset($templates[$id]))
		{
			$template = $templates[$id];
		}
		else
		{
			$template = $templates[0];
		}

Additional comments

[zero-24]

Feel free to send a PR that fix it :)

[joeforjoomla]

Please open a PR at your end or merge the issue to the 3.7 branch

[zero-24]

merge the issue to the 3.7 branch

I'm confused. What should be merged to what? As we are in development of 3.7.0 the staging branch contains the code for 3.7.0 and an issue cant be merged to anything?

[joeforjoomla]

I'm confused too. I've just reported a regression issue that have to be fixed.

[mbabker]

You provided a code solution in your issue and were asked to open a pull request containing your code changes to address the issue.

However also note that section of code purposefully changed in #12688 to address another issue so you will need to validate your proposed changes do not introduce other regressions.

[joeforjoomla]

Well that's not the case, i didn't provided a code solution but only posted and compared the current Joomla 3.6 code and the new Joomla 3.7 code that has the issue.

[mbabker]

Unfortunately just posting a snippet of the 3.6.5 code and saying "this works" doesn't help much, especially since the file's history indicates several changes made in the class (and that method specifically). Isolating a particular change would be helpful because right now there are at least 4 changes to that method alone compared to 3.6.5.

[ghost]

Can't confirm Issue on latest 3.7-staging.

[mbabker]

Probably because the pull request for this issue was merged 3 days ago.