Write to debug log from core code module

Question

I am trying to track down some bugs in an extension, but I need answers from the core code (specifically vendor/magento/module-quote/Model/QuoteRepository.php).

I've tried adding "private $_logger;" to the class declarations, along with adding to the constructor:

public function __construct(
    QuoteFactory $quoteFactory,
    StoreManagerInterface $storeManager,
    \Magento\Quote\Model\ResourceModel\Quote\Collection $quoteCollection,
    \Magento\Quote\Api\Data\CartSearchResultsInterfaceFactory $searchResultsDataFactory,
    JoinProcessorInterface $extensionAttributesJoinProcessor, 
    \Psr\Log\LoggerInterface $logger
) {
    $this->quoteFactory = $quoteFactory;
    $this->storeManager = $storeManager;
    $this->searchResultsDataFactory = $searchResultsDataFactory;
    $this->extensionAttributesJoinProcessor = $extensionAttributesJoinProcessor;
    $this->_logger = $logger;
}

Then I try to write to the log like this:

public function get($cartId, array $sharedStoreIds = [])
{
    $this->_logger->log(\Psr\Log\LogLevel::DEBUG, 'Hello I wrote to the log!');

when the page runs I get the error:

Fatal error: Uncaught TypeError: Argument 6 passed to Magento\Quote\Model\QuoteRepository::__construct() must implement interface Psr\Log\LoggerInterface, none given, called in /home/livean9/public_new/var/generation/Magento/Quote/Model/QuoteRepository/Interceptor.php on line 14 and defined in /home/livean9/public_new/vendor/magento/module-quote/Model/QuoteRepository.php:89

What am I doing wrong?

Answer 1

Try recompiling your DI by running setup:di:compile. That should do the trick.