Magento Imagine 2011 - Magento Debugging - Erik Hansen, Classy Llama Studios
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This document provides tips and techniques for debugging and optimizing Magento code. It discusses enabling developer mode, installing and configuring XDebug, using Mage::log() to log errors and code execution, debugging SQL errors, disabling modules to isolate issues, and using Varien Profiler to optimize slow code. The tips range from basic to advanced techniques for troubleshooting a variety of common Magento problems.
Magento Imagine 2011 - Magento Debugging - Erik Hansen, Classy Llama Studios
- 2. OVERVIEW • Environment configuration • PHP debugging with Magento/Eclipse • Common Magento development problems • Mage::log() • Quick tips
- 3. The Imagine Conference has been excellently planned, but… they made one fatal mistake… One important detail: My name is Erik Hansen
- 4. Erik != Eric
- 6. ENABLE DEVELOPER MODE • Enable Mage::isDeveloperMode() on development and staging environments • Preferably, set the MAGE_IS_DEVELOPER_MODE via .htaccess file or server configuration. Example: • Alternatively, set the developer mode using conditional code in index.php:
- 7. SHOW ALL ERRORS IN DEVELOPER MODE • Modify index.php with this conditional code to ensure that all errors are displayed when in developer mode:
- 9. vs. XDEBUG EXCEPTIONS Links to the location the file Fully expanded argument variables Local variables
- 10. INSTALL XDEBUG • Install Xdebug (an Apache module) on your development/staging servers • My recommended xdebug configuration values: http://bit.ly/gspkIK
- 11. MODIFY THE Mage CLASS • Modify the Mage::run() method to not catch exceptions if developer mode is on (blog post explaining how to make this modification: http://bit.ly/feJE2y)
- 12. MODIFY THE Mage_Core_Model_App CLASS • Modify the Mage_Core_Model_App::setErrorHandler() method to not set an error handler if developer mode is on (blog post explaining how to make this modification: http://bit.ly/co1qc4 )
- 13. CONFIGURE EXCEPTION HANDLER TO EMAIL REPORTS ON A PRODUCTION SITE • Optimize the way that exceptions are handled on a production site • Configure Magento to send email upon every exception
- 15. BASIC XDEBUG/ECLIPSE SETUP • Xdebug – Use config setting from previous slide • Eclipse – Follow configuration instructions below: 1 2
- 16. Link to video: http://www.youtube.com/watch?v=6AynpmjW5us
- 18. UNCOVER THE SOURCE OF SQLSTATE ERRORS • What do you do when Magento throws a generic SQLSTATE database error?
- 19. UNCOVER THE SOURCE OF SQLSTATE ERRORS • Example log file from SQLSTATE error Faulty SQL SQL error query message Backtrace up to point of exception
- 20. UNCOVER THE SOURCE OF SQLSTATE ERRORS • Modify Zend_Db_Adapter_Pdo_Abstract to get backtraces for single queries. • Copy to app/code/local/Zend/Db/Adapter/Pdo/Abstract.php
- 21. UNCOVER THE SOURCE OF SQLSTATE ERRORS • Modify Zend_Db_Statement_Pdo to get backtraces for transactional query errors • Copy to app/code/local/Zend/Db/Adapter/Pdo/Abstract.php
- 22. THINGS TO CHECK WHEN A CUSTOM MODULE DOESN’T LOAD Problem: You’ve created a basic skeleton of a module with a module xml file, config.xml file, 2 layout file, and block, but the module isn’t showing. Here are some quick steps you can take to debug the issue: 3 1
- 23. DEBUGGING BY PROCESS OF ELIMINATION Problem: You are working on a site with 5 third-party modules and 9 custom modules. You’ve heavily modified the way that products work in the system. You run into an error where products aren’t saving from the admin. • You can either: • Work backward by reading code OR: • Isolate the issue by disabling modules
- 24. DEBUGGING BY PROCESS OF ELIMINATION • Disable all custom modules, then selectively re-enable modules until you’ve found the problematic module 1 2 3
- 25. DEBUGGING BY PROCESS OF ELIMINATION • Once the offending module is identified, comment out sections of config.xml to determine component that is causing the error 1 2 3
- 26. VAGUE ERROR MESSAGE Problem: Your client tries to place an order in the admin. When doing so, they get a generic error message about the “The product could not be found”. You check the error and exception logs, but you have nothing to work with. What do you do? 1 2 3
- 27. DISABLING A MODULE VS DISABLING BLOCK OUTPUT V S
- 28. WHEN COLLECTIONS DON’T LOAD THE ITEMS YOU WANT • $collection->load(true, true); logs the query to system.log and prints it to screen • You can then use that query in a SQL tool to see why items aren’t loading • Reference this Knowledge Base article for tips on collections: http://bit.ly/h0itx6
- 29. A MODEL/BLOCK/HELPER REWRITE WON’T WORK… • Is another module trying to override the same model/block/helper that you’re trying to override?
- 31. USING MAGE::LOG – BASIC EXAMPLE • Logging is disabled by default. Enable it in Configuration > Developer > Log Settings • Mage::log() allows you to log code to either the default var/logs/system.log file, or a custom file. • Message gets logged to var/logs/customfile.log
- 32. USING MAGE::LOG – NOTIFICATIONS/ERROR NOTICES
- 33. USING MAGE::LOG – LOGGING API RESPONSES View XML/CGI responses from API calls, like shipping quote requests
- 34. USING MAGE::LOG –DETERMINE CODE COVERAGE Find out if a certain line of code is getting reached. Alternative to using debugger.
- 35. USING MAGE::LOG – VIEWING LOG DATA • You can monitor the contents of the log files using: • Command-line: tail –f <file_name> • OS X: Console.app (Must have developer tools installed) • Windows: Baretail (http://www.baremetalsoft.com/baretail/ )
- 37. CHECK THE BUG TRACKER / FORUMS • Someone may have already solved your problem • If the bug tracker has marked an item as resolved, look in the comments for a code patch, or the SVN trunk
- 38. WILL A NEWER VERSION OF MAGENTO FIX THE ISSUE AT HAND? • Setup upgrade environment and do a quick upgrade to latest production release to see if that solves the issue
- 39. ISOLATE CODE IN A “SANDBOX.PHP” FILE • Allows you to run code outside of the context of a controller/page • Copy index.php to sandbox.php • Modify Mage::run to Mage::app
- 40. GENERAL ADVICE • Don’t get stuck in a certain way of solving problems. • Read (and understand) the code • Before delving into a problem headlong, take a step back and think holistically about the problem
- 41. QUESTIONS?
- 43. OPTIMIZING BUGGY/SLOW CODE W/ VARIEN_PROFILER • Find out what events are getting triggered on a page • How many times is your custom code running? • Optimize slow code
- 44. STANDARD MAGENTO PROFILE (OUTPUT IN HTML TABLE) • You must enable profiler in System > Configuration > Developer > Profile
- 45. CUSTOM MAGENTO PROFILE (OUTPUT TO LOG FILE)
- 46. • Modify index.php 1 2 Profile gets logged to var/log/profiler.log 3
- 47. CUSTOMIZED PROFILE THAT EXTENDS NATIVE PROFILE WITH MYSQL QUERIES • Read about how to implement this on Branko Ajzele’s blog: http://bit.ly/geMSrT
- 48. CONCLUSION • Code samples referenced in slides available here: http://bit.ly/dNNgxU • Eclipse walkthrough video: http://www.youtube.com/watch?v=6AynpmjW5us
Editor's Notes
- #2: • Been doing Magento development for three years. Have come up with ways to more efficiently solve problems and solve bugs. Want to share them with you all.
- #3: I won’t be covering everything in minute detail. At the end of the presentation, I’ll provide a link to slideshow and link to blog posts explaining different sections in more detail.It will be a bit randomSome of you will know this stuff
- #4: They even used my slideshow colors
- #7: • If you have a dedicated stage/dev server, you should setup a global environment variable in your server’s config• Benefit of second method is that you can deploy one codebase without having to change .htaccess file on independent servers.
- #8: • This is elementary, but you want to display errors only on dev/stage environments•Sometimes you have issues with E_NOTICE being turned on, during the checkout and possibly some places in the admin
- #10: You can see all arguments passed to functions in the call stackYou can see all local variables at the location of the error/exceptionYou can customize xdebug to create links that allow you to jump to a specific line/file in your favorite editor
- #12: • Any time you modify core files, have a standard comment notation so you can search codebase for all edits• Make joke about hacking the core
- #14: Use case: You’ve launched a site in production or staging. Users get errors. You either have to check var/logs/exceptions.log on a regular basis, or you can setup to get emailed with these notifications so that you can preempt a store owner contacting you about an issue.This should only be setup this way on a production site. On a development site, you should use xdebug’s exception handling.• Copy errors/local.xml.template to errors/local.xml• The generated exception will be logged to var/log/exceptions.log
- #15: Use cases for debugging:• Understanding how the core system works• Determining non-obvious bugs in your code – ie, bugs that don’t throw errors/exceptions
- #16: Eclipse = PDT or Zend Studio
- #19: • Example errors: Lock wait timeout, integrity constraint errors, out of memory, etc...Especially relevant for errors encountered in the admin panel Modify (harmlessly) two files
- #23: Check if the module’s xml file is loading Create a syntax errorCheck if the module’s config.xml file is loadingCheck if the layout file is loadingMake sure caching is disabled remove the cache directory if it exists (var/cache)
- #24: A completely different approach than jumping directly into the code. Helps isolate the problem
- #27: •Copy the error messageSearch the Magento codebase for the errorOnce you locate the error, set a breakpointUse debug tools to discover the cause of the error
- #28: Disabling block output explainedYou can access this option in System > Configuration > AdvancedDisabling a module’s block output makes the XXXX class not output the contents of any blocks in that moduleWhy would you disable a modules block output as opposed to disabling it? NOTE: Fill in detailsCore Magento classes that are commonly disabledMage_Poll, Mage_Review, Mage_Tag, Mage_Wishlist (NOTE: Need toverifythattherearenoissuesdisablingthesemodule‘s block output)Disabling a moduleChange the <active>true</active> to falseRemove the module’s config file from app/etc/modules
- #32: This is helpful if you want to know what code is calling a specific section of code. This can be helpful when testing methods that are difficult to use a debugger on, such as Paypal code
- #33: Preventative method of doing development
- #35: TODO: Include example output
- #41: Example: Once you get familiar with a debugger, it’s easy to resort to debugging without first reading through the code, checking the bug tracker, etc…Get up, go get a drink, etc… I’ve had more epiphanies about how to solve problems when going pee than anyplace else
- #45: Events & their observers, controller dispatches, model loads, etc…
- #46: Useful for Ajax, Paypal responses, API calls, etc…
- #48: • Useful to determine what your queries look like• If a collection isn’t loading, look at and analyze the query