Here's a list of Joomla code snippets so that I don't have to search the forums every time I need one!

General php

Included files

print 'Debug Line '.__LINE__.' $included <pre>'; print_r (get_included_files()); print "</pre> 
\n";

Paypal IPN History link

Joomla 1.5

Joomla 2.5

Find if on home page

Find current page title

Std DB call

Find current menu text

$active = JFactory::getApplication()->getMenu()->getActive();
$title = $active->title;
.......................................................

Find current menu link from Itemid

$menuitem is the Itemid

$item = JFactory::getApplication()->getMenu()->getItem( $menuitem );
$url = JRoute::_($item->link . '&Itemid=' . $item->id);
.......................................................

Get a var

Just show the component

Show messages in component

Get the messages

Clear joomla messages

Joomla session
set

get

Add module to component
You can also pass prameters - form {"btuser":"83"}

Add js & css

Get User etc

Add a lang file

Joomla 3.0

Resources:

Controller errors

often the libraries/cms/controller & model folder is left behing from J2.5 - remove

Always remove all J1.7 etc com_admin sql files BEFORE beginning!

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replace globals - J3

Add a redirect

Admin toolbar buttons do nothing - J3

replace JToolBarHelper::save();
with JToolbarHelper::save('event.save');

event is the subcontroller name
.......................................................

authorisedLevels - J3

replace Juser::authorisedLevels()
with JUser::getAuthorisedViewLevels()

.......................................................

JFactory::getXMLParser()

replace JFactory::getXMLParser($path)
with JFactory::getXML($path)

and

$xmlparser->loadFile( $path )
with ( string)$xmlparser->version

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$menu = &JSite::getMenu()

replace $menu = &JSite::getMenu()
with $menu = JFactory::getApplication()->getMenu();

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toMySQL() - J3

replace $date->toMySQL();
with $date->toSQL();

.......................................................

JHtml::core() - J3

replace JHtml::core();
with JHtml::_('behavior.framework');

.......................................................

JDate::toFormat() - J3

replace JDate::toFormat();
with JDate::format();

.......................................................

Call to undefined method Joomla\Registry\Registry::getValue() - J3

replace JRegistry::getValue()
with JRegistry::get()

.......................................................

$params->loadJSON( $item->params )

replace $params->loadJSON( $item->params )
with $params->loadString($item->params, 'JSON')

.......................................................

Admin call subcontroller - J3

replace index.php?option=com_ccg&view=events&task=edit&cid[]='. $row->id;
with 'index.php?option=com_ccg&task=events.edit&cid[]='. $row->id;

events is the subcontroller name
.......................................................

JTable::getInstance('event','Jtable') returns nothing - J3

Declaration of JxController::display() should be compatible with JControllerLegacy::display($cachable = false, $urlparams = Array) - J3

Fatal error: Class 'JFolder' not found - J3

cannot extend from interface JController - J3

admin com menu gives 404 (legacy J1.5->2.5 - J3

Call to undefined method Joomla\Registry\Registry::loadJSON() - J3

Fatal error: Class 'JRegistry' - J3

Use of undefined constant DS - J3

500 - Html: :jquery is not supported - J3

500 - JHtmlBehavior::mootools not found or JHtml::core(); - J3

500 - Class 'JParameter' not found - J3

500 - Call to undefined method JModel::getInstance() or JModel::addIncludePath(); - J3

Joomla 3 snippets

Load lang & css from plugin - J3

$language = JFactory::getLanguage();
$language->load('plg_vmcustom_stepbystep', JPATH_PLUGINS . DS . 'vmcustom' .DS . 'stepbystep');
$url= JURI::root(true).'/plugins/vmcustom/stepbystep/assets/css/stepbystep.css';
      $document = JFactory::getDocument();
	  $document->addStyleSheet($url);
          //$document->addScript($script);

Get plugin params anywhere - J3

	$plugin = JPluginHelper::getPlugin('vmcustom', 'stepbystep');
	if ($plugin){
		$params_stepbystep = new JRegistry($plugin->params);
		$sbsdebug = $params_stepbystep->get('sbsdebug', 0);
	}

Bootstrap tooltips - J3

Bootstrap modal - J3

ensure jquery is loaded first before your ext scripts - J3

call content plugin from template/ext - J3

Over-ride Chosen search box show threshold

set html title from article

std DB SET query - J3

std DB SELECT query - J3

Increment Table field

Clean txt string

Loading jquery

Loading BootStrap

Loading mootools

Creating a php object

Report db query error with query

Call any plugin from public

public function onAfterInitialise() {
 $app = $this->app;
 $option = $app->input->get('option');
 if ($option != "com_lscache") {
 return;
 }

 if ($app->isAdmin()) {
 return;
 }

//can use other options
}

Find what is calling Mootools tooltip

Joomla 4.0

Add css from plugin or module not using asset manager

	use Joomla\CMS\Factory;

	use Joomla\CMS\HTML\HTMLHelper;	

	//load css

	HTMLHelper::_('stylesheet', 'modules/mod_vm_hidesold/assets/css/default.css', ['version' => 'auto', 'relative' => true]);

Example Content Security Policy

	
      content="default-src 'self'; 

	  frame-src youtube.com https://www.youtube.com; 

	  font-src 'self' fonts.gstatic.com; style-src 'self' 'unsafe-inline' https://assets.mailerlite.com; 

	  script-src 'self' 'unsafe-inline' https://*.googletagmanager.com
 https://assets.mailerlite.com; 

	  img-src 'self' https://* https://i.ytimg.com https://*.google-analytics.com https://*.googletagmanager.com https://www.google.be  data:;

	  connect-src https://*.google-analytics.com https://*.analytics.google.com https://*.googletagmanager.com;

	  ">

Debug Joomla Database errors

	JLog::add($query, JLog::ERROR, 'database-error');