{Finding Your Way

Understanding Magento Code // @benmarks

https://joind.in/talk/view/8147

Ben Marks4.5 years doing Magento dev2 years as a Magento U instructorHappily employed at Blue Acorn in

Charleston, SC (we're hiring!)Big fan of questions (ask away)

Who am I?

Who knows Magento?

Who are you?

Who knows Magento?Who hates Magento?

Who are you?

Who knows Magento?Who hates Magento?Who doesn't know Magento, but has

been told that they should hate it?

Who are you?

Who knows Magento?Who hates Magento?Who doesn't know Magento, but has

been told that they should hate it?

"Magento doesn't do anything very well" –Harper Reed, php|tek, 2013

Who are you?

ZF1-based MVC frameworkeCommerce ApplicationAnswer to osCommerce

What is Magento?

LOTS of businessLOTS of developer community

membersLOTS of room for innovationLOTS of flexibilityLayout XML

What makes Magento awesome?

LOTS of undocumented features & conventions

LOTS of bad information out thereLOTS of architecture to scaleLOTS of flexibilityLayout XML

What makes Magento difficult?

Supressed error output (index.php):

Caching on by default (Admin Panel):

Disabled output (admin), disabled local code pool (app/etc/local.xml)

Getting Started: Don't Forget!

Declaration: app/etc/modules/Code pool*Type-specific foldersTheme assets

Modules & Module Structure

Declaration: app/etc/modules/

Points to app/code/core/Mage/Connect/etc/config.xml

All modules have config, and all config is merged

Modules & Module Structure

Typical classname-to-path mapping, e.g.:

See app/Mage.php & lib/Varien/Autoload.php:app/code/local/, app/code/community/, app/code/core/, lib/

But... Magento is "all about options," so...

Typical Autoloading

Mage_Catalog_Model_Product_TypeMage/Catalog/Model/Product/Type.php

Reading class group notation

Mage::getModel('catalog/product_type')

<config>

<global>

<models>

<catalog>

<class>Mage_Catalog_Model

Factory Methods & Class Groups

Allows for rewrites:

Mage::getModel('catalog/product_type')

<config>

<global>

<models>

<catalog>

<rewrite>

<product_type>New_Class

Factory Methods & Class Groups

Mage::getModel()

Mage::helper()* Mage::app()->getLayout()->createBlock()

See Mage_Core_Model_Config ::getGroupedClassName()

That's the M, V, and H... but C works differently

Factory Methods & Class Groups

Standard route matching:http://tek13.dev/catalog/product/view/id/51

frontName / controller / action

SEF rewrites: core_url_rewrite table

Controllers

Similar cofiguration-based approach, e.g.:

Mage/Catalog/etc/config.xml

Maps to Mage/Catalog/controllers/Note: not autoloaded

Controllers

Class rewrite/additional route configuration:

Maps to Custom/Module/controllers/

Controllers

Mage_Core_Model_LayoutFactory method for instantiating

blocksGlobal block registryEffectively a singleton, accessed via:

$controller->getLayout()Mage::app()->getLayout()$block->getLayout()

The View: Layout Object

Blocks have two main workflowsInstantiation: _construct() & _prepareLayout()

Rendering: toHtml(), _beforeToHtml(), _afterToHtml()

Blocks are generally responsible for instantiating data models/collections – important for view flexibility

The View: Blocks

Rendering is a waterfall down parent-child relationships:

$parentBlock->getChildHtml('child');

$child->getChildHtml('etc');

//and so forth...

The View: Blocks

How do blocks get called in to scope for rendering? In other words, how does stuff get rendered?

The View: Blocks

Layout XML - up to the developer to use, not use, mix as needed; keep controllers thin!

The View: Layout XML

Layout XML - up to the developer to use, not use, mix as needed; keep controllers thin!

public function exampleAction()

{

$this->loadLayout()->renderLayout();

//$this->getResponse()->setBody('Hi!');

}

The View: Layout XML

Declared in module config.xml; all module layout XML files are compiled always

Layout Update Handles are responsible for limiting the directives for current scope

Full Action Name handle – the missing link

The View: Layout XML

<contacts_index_index /><block /> - type, name, as, template<reference /> - name<remove /> - name<update /> - handle<action /> - methodaction allows to call block public

methods

The View: Layout XML

Layout update handles: applied via PHP; top-level nodes in layout XML files

Block type is class group notation: <block type="page/html_head"> <action method="addJs">

<file>example.js</file>

Mage_Page_Block_Html_Head->addJs('example.js');

The View: Layout XML

Parent-child relationships are established via markup in layout XML...

The View: Layout XML

...and this relationship is seen in templates as well:

Required for rendering to work

The View: Layout XML

Parent-child block relationships can also be set/unset using <action />:

<reference name="root">

<action method="unsetChild">

<child>content</child>

</action>

</reference>

Child exists, but "outside" of rendering flow

The View: Layout XML

Most important thing to understand:

Via layout XML any module can affect any view through the full action name handle or other applied handle (customer_logged_in, etc.)

Let's see some examples from catalog.xml

The View: Layout XML

Config XML is composed of the following:app/etc/*.xmlapp/etc/modules/*.xmlAll active module config.xmlapp/etc/local.xmlcore_config_data table

Configuration XML

Confusingly accessed/evaluated/built; better to learn it by application

Important top level nodes:global frontend & adminhtmladmin default, websites, & stores; often, user-

configurable values here

Configuration XML

Website and store scopes are admin-configurable, but affect config DOM structure (System > Manage Stores)

Possible to declare same xpaths in multiple files and in core_config_data table* (*for default, websites, and stores)

Colliding xpath text values are overwritten when merged

Configuration XML

Convenience method for reading correct value for store scopes

Mage::getStoreConfig('foo/bar/baz');

//same as...

Mage::getConfig()->getNode(

'stores/[code]/foo/bar/baz'

);

Configuration XML

Sometimes it's the node name being evaluated (e.g. module declaration); most of the time it's the text node

Bottom line, it's all about the xpath and the PHP which is evaluating it

Configuration XML

System XML is the quickest way to add user-configurable fields to the admin panel

Default values can be set in files or added to core_config_data via setup scripts

Let's look at Mage/Contacts/etc/system.xml

System XML

Magento CRUD:Create & Update: save()Read: load()Delete: delete()

Data model CRUD works through resource model (see Mage_Core_Model_Abstract)

The Model Layer: CRUD

Hybrid resource / data model classesFiltering, sorting, etc. Lazy loaded.Implement Countable &

IteratorAggregate, making it possible to do this:

The Model Layer: Collections

Generally the best way to customizeEvents are dispatched throughout core

codeAllow to execute code uniformly (e.g.

during request dispatching) or during specific flow of execution (catalog_product_load_after)

Observers

Varien_Object (lib/Varien/Object.php)Basis of blocks and models; for

models, methods map to table columns or attributes

get*, set*, uns*, & has*

$model->getFooBar()

reads from

$model->_data['foo_bar']

Missing code: when __call strikes

Caveat: nothing stops classes from defining getters, setters, etc.

Don't var_dump() objects directly; use Varien_Object->debug() to see properties in _data

Missing code: when __call strikes

The action and the template are the most important aspects to deciphering layout XML; not all blocks use template!

Find the block class via typeCheck the definition to see if the method

is declared or notA simple echo get_class($this) in the

template will suffice

Missing code: layout XML

Observer configuration can be found mainly under the xpaths global/events, frontend/events, and adminhtml/events

Many events are dynamicMultiple observers can be configured

for the same event

Missing code: Observers

When an install is not behaving as expected, check for Mage, Varien, and Zend namespaces outside of core or lib

Check for event observer configuration for targeted CRUD and reques operations

Missing code: Miscellaneous

When content is being rendered with no apparent source in template or entity data, suspect translations, which can reside in translate.csv, app/locale/, or core_translate table; translate="" & __("Some String")

CMS pages, categories, and products all have custom design settings (themes & layout XML) which are stored in the database

Missing code: Miscellaneous

Module code not executing.

Is config being merged? Enable developer mode & clear cache. Error message indicates everything is ok. 80% of all problems start with config.*

Troubleshooting Process

Unexpected or missing theme-related content.

Reset the theme to default to rule out issues from custom templates & layout XML; check database for layout XML, template, and theme settings. Check parent-child relationships.

Troubleshooting Process

Class XYZ is not behaving correctly.

Check for a config-based rewrite, an include path override, or an event observer.

Collection class/view seems to be slow.

Ensure that the collection class is building correct data and that models are not being loaded iteratively.

Troubleshooting Process

Enable profiler in two places:System > Configuration > Developer index.php - uncomment Varien_Profiler::enable()

Rudimentary output; read from outside-in till you get to the bottom-most entry with longest execution time

Enable query profiler in config xml atglobal/resources/default_setup/connection/profiler

Profiler

Enable TPH in admin: System > Configuraration > Developer Change scope from "Default"

Pretty ugly, and missing key info (such as alias, name). Check out AOE_TemplateHints v2.0 http://www.fabrizio-branca.de/magento-advanced-template-hints-20.html

Template Path Hints

ben@blueacorn.comhttp://twitter.com/benmarks

Me

http://stackoverflow.com/questions/tagged/magento

http://magento.stackexchange.com/ http://alanstorm.com/http://magebase.com/http://www.fabrizio-branca.de/magento

-modules.htmlhttp://blueacorn.com/

Resources

Magicento plugin for PhpStormhttp://magicento.com/

n98-magerun:https://github.com/netz98/n98-magerun

Feedback:https://joind.in/talk/view/8147

Resources