Some common code snippets

1. Debugging

\TYPO3\CMS\Core\Utility\DebugUtility::debug()
// or you can use
// debug(); if you are in a development mode

2. TYPO3 Annotations

/**
 * Some of the annotations used in TYPO3
 *
 * @TYPO3\CMS\Extbase\Annotation\ORM\Lazy
 * @TYPO3\CMS\Extbase\Annotation\ORM\Cascade("remove")
 * @TYPO3\CMS\Extbase\Annotation\Validate("NotEmpty")
 * @TYPO3\CMS\Extbase\Annotation\Validate("EmailAddress")
 * @TYPO3\CMS\Extbase\Annotation\Inject
 * @TYPO3\CMS\Extbase\Annotation\IgnoreValidation("domainObject")
 */

3. Fill ObjectStorage from QueryResult

/**
 * Fill objectStorage from QueryResult
 *
 * @param \TYPO3\CMS\Extbase\Persistence\QueryResultInterface $queryResult
 * @return \TYPO3\CMS\Extbase\Persistence\ObjectStorage
 */
protected function fillOjectStorageFromQueryResult(
    \TYPO3\CMS\Extbase\Persistence\QueryResultInterface $queryResult=NULL
    )
{
    /* @var $objectStorage \TYPO3\CMS\Extbase\Persistence\ObjectStorage */
    $objectStorage = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(
        \TYPO3\CMS\Extbase\Persistence\ObjectStorage::class
    );

    if (NULL!==$queryResult) {
        foreach($queryResult AS $object) {
            $objectStorage->attach($object);
        }
    }

    return $objectStorage;
}

4. Default ordering in repository

protected $defaultOrderings = array(
    'number' => \TYPO3\CMS\Extbase\Persistence\QueryInterface::ORDER_ASCENDING,
);

5. Do not respect storage pid

public function initializeObject()
{
    $querySettings = $this->objectManager->get(
        \TYPO3\CMS\Extbase\Persistence\Generic\Typo3QuerySettings::class
    );
    $querySettings->setRespectStoragePage(FALSE);
    $this->setDefaultQuerySettings($querySettings);
}

6. Get Path

\TYPO3\CMS\Core\Utility\ExtensionManagementUtility::extPath('YOUR_EXTENSION_KEY'); //Extension' apth
\TYPO3\CMS\Core\Core\Environment::getPublicPath(); // Public path

7. Set TypeConverter for date

function initializeCreateAction()
{
    $dateformat = 'Y-m-d';
    $this->arguments->getArgument('newJob')
        ->getPropertyMappingConfiguration()
        ->forProperty('expiryDate')
        ->setTypeConverterOption(
        \TYPO3\CMS\Extbase\Property\TypeConverter\DateTimeConverter::class,
        \TYPO3\CMS\Extbase\Property\TypeConverter\DateTimeConverter::CONFIGURATION_DATE_FORMAT,
        $dateformat
    );
}

8. Get Extension Configuration

/**
 * function to get extension configuration
 *
 * @param string $configVar
 * @return mixed
 */
public function getExtensionConfiguration(string $configVar)
{
    $extensionConfiguration = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(
        \TYPO3\CMS\Core\Configuration\ExtensionConfiguration::class
    );

    return $extensionConfiguration->get('YOU_EXTENSION_NAME', $configVar);
}

9. Get Logger

protected static function getLogger()
{
    return \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(
        \TYPO3\CMS\Core\Log\LogManager::class
    )->getLogger(__CLASS__);
}