WritingMagentoModules.md # Writing Magento ModulesAll custom modules should have a **Namespace** and **Module Name**.These are used below as `{Namespace}` and `{Module}`. **Caution:** The Magento autoloader is known to have problems with Ca
# Writing Magento Modules
All custom modules should have a **Namespace** and **Module Name**.
These are used below as `{Namespace}` and `{Module}`.
> **Caution:** The Magento autoloader is known to have problems with CamelCase namespaces and/or modules between Windows and *nix systems. If your module requires more than one word for either of these, it is best to just concatenate them to avoid any issues (Example: `{Namespace}_{Examplemodule}`).
## Index
* [Directory Structure](#directory_structure)
* [Setup](#setup)
* [Tell Magento how to load your module](#step1)
* [Create your module's configuration](#step2)
* [Create your module's administration settings](#step3) (optional)
* [Write your module classes](#classes)
* [Blocks](#blocks)
* [Controllers](#controllers)
* [Frontend](#frontend)
* [Backend (Admin)](#backend)
* [Helpers](#helpers)
* [Models](#models)
* [Data Models](#data)
* [Resource Models](#resource)
* [Observers](#observers)
* [Extending Magento classes](#extending)
* [Tips](#tips)
## Standard Directory Structure
> **Note:** Not all paths are required (`app/design`, `skin`), only implement the ones you need.
```python
+-app
| +-code
| | +-local
| | +-{Namespace}
| | +-{Module}
| | +-Block
| | | +-Adminhtml
| | +-controllers
| | | +-Adminhtml
| | | | +-{ControllerName}Controller.php # Backend controller
| | | +-{ControllerName}Controller.php # Frontend controller
| | +-etc
| | | +-adminhtml.xml # Admin ACL and other settings
| | | +-config.xml # Configuration settings for your module
| | | +-system.xml # Administration settings and form options
| | +-Helper
| | | +-Data.php
| | +-Model
| | | +-Resource
| | | | +-{EntityName}
| | | | | +-Collection.php # Collection model for {entity}
| | | | +-{EntityName}.php # Resource model for {entity}
| | | +-Observer.php # Used for subscribing to Magento events
| | | +-{EntityName}.php # Data model for {entity}
| | +-sql
| | | +-{namespace}_{module}_setup
| | | +-mysql4-install-{X}.{X}.{X}.php
| | | +-mysql4-upgrade-{X}.{X}.{X}-{X}.{X}.{X}.php
| | +-Test
| +-design
| | +-adminhtml
| | | +-default
| | | +-default
| | | +-layout
| | | | +-{namespace}
| | | | +-{module}.xml
| | | +-template
| | | +-{namespace}
| | | +-{module}
| | +-frontend
| | +-base
| | +-default
| | +-layout
| | | +-{namespace}
| | | +-{module}.xml
| | +-template
| | +-{namespace}
| | +-{module}
| +-etc
| +-modules
| +-{Namespace}_{Module}.xml
+-skin
+-adminhtml
| +-default
| +-default
| +-css
| | +-{namespace}
| | +-{module}
| +-images
| | +-{namespace}
| | +-{module}
| +-js
| +-{namespace}
| +-{module}
+-frontend
+-base
+-default
+-css
| +-{namespace}
| +-{module}
+-images
| +-{namespace}
| +-{module}
+-js
+-{namespace}
+-{module}
```
## Setup
### 1. Tell Magento how to load your module
Magento needs to know that it should load your module and where to find it. For this, create an XML file under `app/etc/modules/{Namespace}_{Module}.xml`:
```xml
<{Namespace}_{Example}>
true
local
```
The `
` block above is for illustrative purposes only. If your module requires others to be loaded before it, list them under `
` - otherwise you can remove it or replace it with an empty node (`
<{Namespace}_{Example}>
{X}.{X}.{X}
<{namespace}_{module}>
{Namespace}_{Example}_Block
<{namespace}_{module}>
{Namespace}_{Example}_Helper
<{namespace}_{module}>
{Namespace}_{Example}_Model
{namespace}_{module}_resource
<{namespace}_{module}_resource>
{Namespace}_{Example}_Model_Resource
<{entity_name}}>
{namespace}_{module}_{table_name}
<{namespace}_{module}_setup>
{Namespace}_{Example}
<{namespace}_{module}_write>
<{namespace}_{module}_read>
<{event_name}>
<{namespace}_{module}_{event_name}>
model
{namespace}_{module}/observer
{methodName}
<{namespace}_{module} before="Mage_Adminhtml">{Namespace}_{Example}_Adminhtml
<{namespace}_{module}>
{namespace}/{module}.xml
<{namespace}_{module}>
{Namespace}_{Example}
{namespace}
<{namespace}_{module}>
{namespace}/{module}.xml
<{namespace}_{module}> <{group_name}>
0
0
<{namespace}_{module}_{job_name}>
* * * * *
{namespace}_{module}/observer::{methodName}
``` The comments above should explain which sections can be removed if your module does not require/need them. > **Note:** Be sure to replace `{X}.{X}.{X}` with your module's version number (Example: `1.0.0`). This number is stored in the database table `core_resource` and is also used for running module setup scripts under `app/code/local/{Namespace}/{Module}/sql/{namespace}_{module}_setup`.
### 3. Create your module's administration settings (optional) Create the file `system.xml` under `app/code/local/{Namespace}/{Module}/etc`. Within this file you can define custom admin configuration tabs, admin settings, etc. Two example settings are included below (`enabled` and `debug`) which provide simple on/off settings in the Magento administration interface. ```xml
<{namespace}_{module} translate="label" module="{namespace}_{module}">
300
<{namespace}_{module} translate="label" module="{namespace}_{module}">
{namespace}_{module}
1
1
1
1
<{group_name} translate="label">
1
1
1
1
select
adminhtml/system_config_source_yesno
1
1
0
0
1
select
adminhtml/system_config_source_enabledisable
2
1
0
0
``` > **Note:** Each setting relates to the `
` key in `config.xml` - which specifies that setting's default value. In order for the settings to show up/work - you must also create ACL rules for your new admin config section. For that, we need to create `adminhtml.xml` under `app/code/local/{Namespace}/{Module}/etc`. ```xml
<{namespace}_{module] translate="title" module="{namespace}_{module]">
{Namespace} {Module}
1
``` > **Note:** For older Magento versions, it is necessary to also specify the above `
` area under the `
` section of `config.xml`.
## Write your module classes
### Blocks Blocks control the HTML output of a specific section/area of various pages within Magento. You can create your own blocks but the most common use is to extend another Magento block. ```php
getRequest()->getParam('query_parameter', 'Default Value (if not present)'); // Example of getting a URL from the router $url = Mage::app()->getStore()->getUrl('{module}/{controller}'); // Example of performing a redirect $this->_redirectUrl($url); } } ```
#### Backend (Admin) ```php
loadLayout() ->_setActiveMenu('{menu_name}') ->_addBreadcrumb( '{Breadcrumb Text}', '{Breadcrumb Text}', // ... ); return $this; } public function {actionName}Action() { $this->_title('{Title Text}'); $this->_initAction()->renderLayout(); // Example of adding a success notice message Mage::getSingleton('adminhtml/session')->addSuccess('{Success Message Text}'); // Example of adding an error notice message Mage::getSingleton('adminhtml/session')->addError('{Error Message Text}'); } } ```
### Helpers You must create one Helper class, however - it can remain empty. These classes are used for general functions/methods that are required between different class types (Example: retrieving configuration values). ```php
**Note:** This class can then be retrieved with: `Mage::helper('{namespace}_{module}')`
### Models Models can be broken into 2 types: [data models](#data) and [resource models](#resource). Resource models control the interaction with the database (MySQL) whereas data models can range in responsibilities but usually manipulate data between controllers and resource models.
#### Data Model ```php
_init('{namespace}_{module}/{entity_name}'); } } ``` > **Note:** This class can then be retrieved with: `Mage::getModel('{namespace}_{module}/{entity_name}')`
#### Resource Model ```php
_init('{namespace}_{module}/{entity_name}', '{primary_key}'); } } ``` > **Note:** This class can then be retrieved with: `Mage::getResourceModel('{namespace}_{module}/{entity_name}')` However, it is common practice to retrieve it from the data model instance: `Mage::getModel('{namespace}_{module}/{entity_name}')->getResource()` You can also (optionally) define the Collection class used. The Collection is used to handle many instances of your resource models (saving many rows, retrieving many rows, iterating, etc.). ```php
_init('{namespace}_{module}/{entity_name}'); } } ``` > **Note:** This class can then be retrieved from the data modal instance with: `Mage::getModel('{namespace}_{module}/{entity_name}')->getCollection()`
#### Observers The easiest and most flexible way of extending Magento features is by listening and responding to events with an observer class. Which events your module listens for is defined in your module's `config.xml`. ```php
``` Here is an example of rewriting `Mage_Core_Model_Email_Template` with `Acme_Custom_Model_Email_Template`: ```xml
Acme_Custom_Model_Email_Message
``` > **Caution:** It is important to remember that core Magento modules (those namespaced with `Mage_`) do not require the use of `mage_`. So the example above uses just `core` rather than `mage_core`. ## Tips #### `var_dump()` and Magento Trying to `var_dump()` a Magento class instance will quickly lead to headaches because of circular references. Most Magento classes extend `Varien_Object` and thus expose a `debug()` method which is much better for dumping: ```php
debug()); ``` #### Logging The easiest way to write to the system logger (or your own custom log file) is to use the `log()` method exposed by the `Mage` class: ```php