Contao Open Source CMS > Understand > Developer's guide > Customizing Contao > How to add custom functionality to Contao using hooks

Contao hooks

Hooks work similar to the callback functions of the Data Container Array. You can register one or more functions for a certain event and when the event is triggered, the callback functions are executed. Hooks allow you to add custom functionality to the core.

activateAccount ¶

The activateAccount hook is triggered when a new front end account is activated. It passes the user object as argument and does not expect a return value. It is available from version 2.4.3.

// config.php
$GLOBALS['TL_HOOKS']['activateAccount'][] = array('MyClass', 'myActivateAccount');

// MyClass.php
public function myActivateAccount(Database_Result $objUser)
{
    // Do something
}

activateRecipient ¶

The activateRecipient hook is triggered when a new newsletter recipient is added. It passes the e-mail address, the recipient IDs and the channel IDs as argument and does not expect a return value. It is available from version 2.8.RC1.

// config.php
$GLOBALS['TL_HOOKS']['activateRecipient'][] = array('MyClass', 'myActivateRecipient');

// MyClass.php
public function myActivateRecipient($strEmail, $arrRecipients, $arrChannels)
{
    // Do something
}

addComment ¶

The addComment hook is triggered when a comment is added. It passes the ID of the record and the data array as arguments and does not expect a return value. It is available from version 2.8.2.

// config.php
$GLOBALS['TL_HOOKS']['addComment'][] = array('MyClass', 'myAddComment');

// MyClass.php
public function myAddComment($intId, $arrSet)
{
    // Do something
}

addCustomRegexp ¶

The addCustomRegexp hook is triggered when an unknown regular expression is found. It passes the name of the regexp, the current value and the widget object as arguments and expects a boolean return value. It is available from version 2.6.2.

// config.php
$GLOBALS['TL_HOOKS']['addCustomRegexp'][] = array('MyClass', 'myAddCustomRegexp');

// MyClass.php
public function myAddCustomRegexp($strRegexp, $varValue, Widget $objWidget)
{
    if ($strRegexp == 'postal')
    {
        if (!preg_match('/^0-9{4,6}$/', $varValue))
        {
            $objWidget->addError('Field ' . $objWidget->label . ' should be a postal code.');
        }

        return true;
    }

    return false;
}

addLogEntry ¶

The addLogEntry hook is triggered when a new log entry is added. It passes the message, the function and the action as arguments and does not expect a return value. It is available from version 2.8.RC1.

// config.php
$GLOBALS['TL_HOOKS']['addLogEntry'][] = array('MyClass', 'myAddLogEntry');

// MyClass.php
public function myAddLogEntry($strText, $strFunction, $strAction)
{
    // Do something
}

checkCredentials ¶

The checkCredentials hook is triggered when a login attempt fails due to a wrong password. It passes the username and password as well as the user object as arguments and expects a boolean return value. It is available from version 2.6.0.

// config.php
$GLOBALS['TL_HOOKS']['checkCredentials'][] = array('MyClass', 'myCheckCredentials');

// MyClass.php
public function myCheckCredentials($strUsername, $strPassword, User $objUser)
{
    // Check against a global database
    if ($this->checkGlobalDbFor($strUsername, $strPassword))
    {
        return true;
    }

    return false;
}

closeAccount ¶

The closeAccount hook is triggered when a user closes his account. It passes the user ID, the operation mode and the module as arguments and does not expect a return value. It is available from version 2.8.0.

// config.php
$GLOBALS['TL_HOOKS']['closeAccount'][] = array('MyClass', 'myCloseAccount');

// MyClass.php
public function myCloseAccount($intId, $strMode, $objModule)
{
    if ($strMode == 'close_delete')
    {
        // Do something
    }
}

compileDefinition ¶

The compileDefinition hook is triggered when a format definition of a style sheet is written. It passes the configuration array as argument and expects a string as return value. It is available from version 2.9.4.

// config.php
$GLOBALS['TL_HOOKS']['compileDefinition'][] = array('MyClass', 'myCompileDefinition');

// MyClass.php
public function myCompileDefinition($arrRow)
{
    if (isset($arrRow['border-radius']))
    {
        return "\nborder-radius:" . $arrRow['border-radius'] . ";";
    }

    return '';
}

createDefinition ¶

The createDefinition hook is triggered when a format definition of a style sheet is imported. It passes the key and value, the original format definition and the data array as arguments and expects an array or false as return value. It is available from version 2.9.4.

// config.php
$GLOBALS['TL_HOOKS']['createDefinition'][] = array('MyClass', 'myCreateDefinition');

// MyClass.php
public function myCreateDefinition($strKey, $strValue, $strDefinition, $arrSet)
{
    if ($strKey == 'border-radius')
    {
        return array('border-radius'=>$strValue);
    }

    return false;
}

createNewUser ¶

The createNewUser hook is triggered when a new front end user registers on the website. It passes the ID of the new user and the data array as arguments and does not expect a return value. It is available from version 2.2.0.

// config.php
$GLOBALS['TL_HOOKS']['createNewUser'][] = array('MyClass', 'myCreateNewUser');

// MyClass.php
public function myCreateNewUser($intId, $arrData)
{
    // Modify the record
}

executePreActions ¶

The executePreActions hook is triggered on Ajax requests that do not require a DCA object. It passes the name of the action as argument and does not expect a return value. It is available from version 2.6.1.

// config.php
$GLOBALS['TL_HOOKS']['executePreActions'][] = array('MyClass', 'myExecutePreActions');

// MyClass.php
public function myExecutePreActions($strAction)
{
    if ($strAction == 'update')
    {
        // Do something
    }
}

executePostActions ¶

The executePostActions hook is triggered on Ajax requests that require a DCA object. It passes the name of the action and the data container object as arguments and does not expect a return value. It is available from version 2.6.1.

// config.php
$GLOBALS['TL_HOOKS']['executePostActions'][] = array('MyClass', 'myExecutePostActions');

// MyClass.php
public function myExecutePostActions($strAction, DataContainer $dc)
{
    if ($strAction == 'update')
    {
        // Do something
    }
}

generateFrontendUrl ¶

The generateFrontendUrl hook is triggered when a front end URL is recreated. It passes the page object, the parameter string and the default URL as arguments and expects a string as return value. It is available from version 2.5.8.

// config.php
$GLOBALS['TL_HOOKS']['generateFrontendUrl'][] = array('MyClass', 'myGenerateFrontendUrl');

// MyClass.php
public function myGenerateFrontendUrl($arrRow, $strParams, $strUrl)
{
    return str_replace('.html', '.xml', $strUrl);
}

generatePage ¶

The generatePage hook is triggered before the main layout (fe_page) is compiled. It passes the page object, the layout object and a self-reference as arguments and does not expect a return value. It is available from version 2.8.RC1.

// config.php
$GLOBALS['TL_HOOKS']['generatePage'][] = array('MyClass', 'myGeneratePage');

// MyClass.php
public function myGeneratePage(Database_Result $objPage, Database_Result $objLayout, PageRegular $objPageRegular)
{
    // Do something
}

getAllEvents ¶

The getAllEvents hook allows you to modify the result sets of calendar and event modules. It passes the current result set, the IDs of the parent items and the start and end time as arguments and expects a result set (array) as return value. It is available from version 2.6.4.

// config.php
$GLOBALS['TL_HOOKS']['getAllEvents'][] = array('MyClass', 'myGetAllEvents');

// MyClass.php
public function myGetAllEvents($arrEvents, $arrCalendars, $intStart, $intEnd, Module $objModule)
{
    ksort($arrEvents);
    return $arrEvents;
}

getContentElement ¶

The getContentElement hook is triggered when a content element is rendered. It passes the database object and the buffer string as arguments and expects a buffer string as return value. It is available from version 2.9.0.

// config.php
$GLOBALS['TL_HOOKS']['getContentElement'][] = array('MyClass', 'myGetContentElement');

// MyClass.php
public function myGetContentElement(Database_Result $objElement, $strBuffer)
{
    return $strBuffer;
}

getImage ¶

The getImage hook is triggered when a thumbnail is generated and allows you to add a custom routine. It passes the path, the width and height, the mode, the cache name and the file object as arguments and expects a path as return value. It is available from version 2.8.RC1.

// config.php
$GLOBALS['TL_HOOKS']['getImage'][] = array('MyClass', 'myGetImage');

// MyClass.php
public function myGetImage($image, $width, $height, $mode, $strCacheName, $objFile)
{
    return MyImage::generateThumbnail($image, $widht, $height, $mode);
}

getPageIdFromUrl ¶

The getPageIdFromUrl hook is triggered when the URL fragments are evaluated. It passes the array of URL fragments as argument and expects an array of URL fragments as return value. It is available from version 2.5.4.

// config.php
$GLOBALS['TL_HOOKS']['getPageIdFromUrl'][] = array('MyClass', 'myGetPageIdFromUrl');

// MyClass.php
public function myGetPageIdFromUrl($arrFragments)
{
    return array_unique($arrFragments);
}

getSearchablePages ¶

The getSearchablePages hook is triggered when the the search index is rebuilt. It passes the array of pages and the ID of the root page as arguments and expects an array of absolute URLs (!) as return value. It is available from version 2.2.0.

// config.php
$GLOBALS['TL_HOOKS']['getSearchablePages'][] = array('MyClass', 'myGetSearchablePages');

// MyClass.php
public function myGetSearchablePages($arrPages, $intRoot)
{
    return array_merge($arrPages, array('Additional pages'));
}

importUser ¶

The importUser hook is triggered when a username cannot be found in the database. It passes the username, the password and the table name as arguments and expects a boolean return value. It is available from version 2.7.RC1.

// config.php
$GLOBALS['TL_HOOKS']['importUser'][] = array('MyClass', 'myImportUser');

// MyClass.php
public function myImportUser($strUsername, $strPassword, $strTable)
{
    if ($strTable == 'tl_member')
    {
        // Import user from an LDAP server
        if ($this->importUserFromLdap($strUsername, $strPassword))
        {
            return true;
        }
    }

    return false;
}

listComments ¶

The listComments hook is triggered when comments are listed in the back end. It passes the current record as argument and expects a string as return value. It is available from version 2.8.RC2.

// config.php
$GLOBALS['TL_HOOKS']['listComments'][] = array('MyClass', 'myListComments');

// MyClass.php
public function myListComments($arrRow)
{
    return '<a href="contao/main.php?do= … ">' . $arrRow['title'] . '</a>';
}

loadFormField ¶

The loadFormField hook is triggered when a form field is loaded. It passes the widget object, the form ID and the form data as arguments and expects a widget object as return value. It is available from version 2.5.0.

// config.php
$GLOBALS['TL_HOOKS']['loadFormField'][] = array('MyClass', 'myLoadFormField');

// MyClass.php
public function myLoadFormField(Widget $objWidget, $strForm, $arrForm)
{
    $objWidget->class = 'myclass';
    return $objWidget;
}

loadDataContainer ¶

The loadDataContainer hook is triggered when a DCA file is loaded. It passes the file name as argument and does not expect a return value. It is available from version 2.8.2.

// config.php
$GLOBALS['TL_HOOKS']['loadDataContainer'][] = array('MyClass', 'myLoadDataContainer');

// MyClass.php
public function myLoadDataContainer($strName)
{
    // Do something
}

loadLanguageFile ¶

The loadLanguageFile hook is triggered when a language file is loaded. It passes the file name and the language as arguments and does not expect a return value. It is available from version 2.8.RC1.

// config.php
$GLOBALS['TL_HOOKS']['loadLanguageFile'][] = array('MyClass', 'myLoadLanguageFile');

// MyClass.php
public function myLoadLanguageFile($strName, $strLanguage)
{
    // Do something
}

outputBackendTemplate ¶

The outputBackendTemplate hook is triggered when a back end template is printed to the screen. It passes the template content and the template name as arguments and expects the template content as return value. It is available from version 2.6.0.

// config.php
$GLOBALS['TL_HOOKS']['outputBackendTemplate'][] = array('MyClass', 'myOutputBackendTemplate');

// MyClass.php
public function myOutputBackendTemplate($strContent, $strTemplate)
{
    if ($strTemplate == 'be_main')
    {
        // Modify output
    }

    return $strContent;
}

outputFrontendTemplate ¶

The outputFrontendTemplate hook is triggered when a front end template is printed to the screen. It passes the template content and the template name as arguments and expects the template content as return value. It is available from version 2.6.0.

// config.php
$GLOBALS['TL_HOOKS']['outputFrontendTemplate'][] = array('MyClass', 'myOutputFrontendTemplate');

// MyClass.php
public function myOutputFrontendTemplate($strContent, $strTemplate)
{
    if ($strTemplate == 'fe_page')
    {
        // Modify output
    }

    return $strContent;
}

parseBackendTemplate ¶

The parseBackendTemplate hook is triggered when a back end template is parsed. It passes the template content and the template name as arguments and expects the template content as return value. It is available from version 2.6.0.

// config.php
$GLOBALS['TL_HOOKS']['parseBackendTemplate'][] = array('MyClass', 'myParseBackendTemplate');

// MyClass.php
public function myParseBackendTemplate($strContent, $strTemplate)
{
    if ($strTemplate == 'be_main')
    {
        // Modify output
    }

    return $strContent;
}

parseFrontendTemplate ¶

The parseFrontendTemplate hook is triggered when a front end template is parsed. It passes the template content and the template name as arguments and expects the template content as return value. It is available from version 2.6.0.

// config.php
$GLOBALS['TL_HOOKS']['parseFrontendTemplate'][] = array('MyClass', 'myParseFrontendTemplate');

// MyClass.php
public function myParseFrontendTemplate($strContent, $strTemplate)
{
    if ($strTemplate == 'ce_text')
    {
        // Modify output
    }

    return $strContent;
}

postDownload ¶

The postDownload hook is triggered after a file has been downloaded with the download(s) element. It passes the file name as argument and does not expect a return value. It is available from version 2.4.6.

// config.php
$GLOBALS['TL_HOOKS']['postDownload'][] = array('MyClass', 'myPostDownload');

// MyClass.php
public function myPostDownload($strFile)
{
    // Do something
}

postLogin ¶

The postLogin hook is triggered after a user has logged into the front end. It passes the user object as argument and does not expect a return value. It is available from version 2.4.3.

// config.php
$GLOBALS['TL_HOOKS']['postLogin'][] = array('MyClass', 'myPostLogin');

// MyClass.php
public function myPostLogin(FrontendUser $objUser)
{
    // Do something
}

postLogout ¶

The postLogout hook is triggered after a user has logged out from the front end. It passes the user object as argument and does not expect a return value. It is available from version 2.4.3.

// config.php
$GLOBALS['TL_HOOKS']['postLogout'][] = array('MyClass', 'myPostLogout');

// MyClass.php
public function myPostLogout(FrontendUser $objUser)
{
    // Do something
}

postUpload ¶

The postUpload hook is triggered after a user has uploaded one or more file in the back end. It passes an array of filenames as argument and does not expect a return value. It is available from version 2.6.4.

// config.php
$GLOBALS['TL_HOOKS']['postUpload'][] = array('MyClass', 'myPostUpload');

// MyClass.php
public function myPostUpload($arrFiles)
{
    // Do something
}

printArticleAsPdf ¶

The printArticleAsPdf hook is triggered when an article is exported as PDF. It passes the article text and the article object as arguments and does not expect a return value. It is available from version 2.8.RC1.

// config.php
$GLOBALS['TL_HOOKS']['printArticleAsPdf'][] = array('MyClass', 'myPrintArticleAsPdf');

// MyClass.php
public function myPrintArticleAsPdf($strArticle, Database_Result $objArticle)
{
    // Do something
    exit;
}

processFormData ¶

The processFormData hook is triggered after a form has been submitted. It passes the form data array, the Data Container Array and the files array as arguments and does not expect a return value. It is available from version 2.4.4.

// config.php
$GLOBALS['TL_HOOKS']['processFormData'][] = array('MyClass', 'myProcessFormData');

// MyClass.php
public function myProcessFormData($arrPost, $arrForm, $arrFiles)
{
    // Do something
}

removeOldFeeds ¶

The removeOldFeeds hook is triggered when old XML files are being removed from the Contao directory. It does not pass an argument and expects an array of file names to preserve as return value. It is available from version 2.5.8.

// config.php
$GLOBALS['TL_HOOKS']['removeOldFeeds'][] = array('MyClass', 'myRemoveOldFeeds');

// MyClass.php
public function myRemoveOldFeeds()
{
    return array('custom.xml');
}

removeRecipient ¶

The removeRecipient hook is triggered when a newsletter recipient is removed. It passes the e-mail address and the channel IDs as argument and does not expect a return value. It is available from version 2.8.RC1.

// config.php
$GLOBALS['TL_HOOKS']['removeRecipient'][] = array('MyClass', 'myRemoveRecipient');

// MyClass.php
public function myRemoveRecipient($strEmail, $arrChannels)
{
    // Do something
}

replaceInsertTags ¶

The replaceInsertTags hook is triggered when an unknown insert tag is found. It passes the insert tag as argument and expects the replacement value or false as return value. It is available from version 2.6.0.

// config.php
$GLOBALS['TL_HOOKS']['replaceInsertTags'][] = array('MyClass', 'myReplaceInsertTags');

// MyClass.php
public function myReplaceInsertTags($strTag)
{
    if ($strTag == 'mytag')
    {
        return 'mytag replacement';
    }

    return false;
}

reviseTable ¶

The reviseTable hook is triggered when Contao removes orphan records from a table. It passes the name of the current table, the IDs of all new records, the name of the parent table and the names of all child tables as arguments and does expect a boolean return value (returning true will cause the current page to be reloaded). It is available from version 2.6.4.

// config.php
$GLOBALS['TL_HOOKS']['reviseTable'][] = array('MyClass', 'myReviseTable');

// MyClass.php
public function myReviseTable($table, $new_records, $parent_table, $child_tables)
{
    // Do something
}

setNewPassword ¶

The setNewPassword hook is triggered after a new password has been set. It passes the user object and the encrypted password as arguments and does not expect a return value. It is available from version 2.2.3.

// config.php
$GLOBALS['TL_HOOKS']['setNewPassword'][] = array('MyClass', 'mySetNewPassword');

// MyClass.php
public function mySetNewPassword($objUser, $strPassword)
{
    // Do something
}

validateFormField ¶

The validateFormField hook is triggered when a form field is submitted. It passes the widget object and the form ID as arguments and expects a widget object as return value. It is available from version 2.5.0.

// config.php
$GLOBALS['TL_HOOKS']['validateFormField'][] = array('MyClass', 'myValidateFormField');

// MyClass.php
public function myValidateFormField(Widget $objWidget, $intId)
{
    if ($objWidget instanceof FormPassword)
    {
        // Do something
    }

    return $objWidget;
}

Add a comment

Comment by Kamil Kuzminski | June 22nd, 2011

The getSearchablePages hook is also launched when the sitemap is being generated.

Comment by Kamil Kuzminski | August 30th, 2011

If you need to use two callbacks "postLogin" and "postLogout", you can assign both of them to one function:

public function postLoginLogout(FrontendUser $objUser)
{
    // User logs in
    if (!FE_USER_LOGGED_IN)
    {
        // ...
    }

    // User logs out
    else
    {
        // ...
    }
}

Comment by Tsarma | September 5th, 2011

The generateBreadcrumb Hook is not mentioned here although it is also available. With which you may manipulate navigation items before its out put.

Comment by Fred | September 14th, 2011

Undocumented Hook:

if (isset($GLOBALS['TL_HOOKS']['updatePersonalData']) && is_array($GLOBALS['TL_HOOKS']['updatePersonalData']))
{
  foreach ($GLOBALS['TL_HOOKS']['updatePersonalData'] as $callback)
  {
    $this->import($callback[0]);
    $this->$callback[0]->$callback[1]($this->User, $_SESSION['FORM_DATA']);
  }
}

Comment by Kamil Kuzminski | September 28th, 2011

The postLogin example probably won't work correctly in Contao 2.10 and above, because it is also triggered when the back end user logs in. Thus to make it work you need to change the code like here:

Code:

public function postLogin($objUser)
{
	// Front end
	if (TL_MODE == 'FE')
	{

	}
	
	// Back end
	elseif (TL_MODE == 'BE')
	{

	}
}

Comment by Kamil Kuzminski | December 23rd, 2011

Note that the getSearchablePages() doesn't pass the root ID anymore!