[php] How to get data from Magento System Configuration

Magento 1.x

(magento 2 example provided below)

sectionName, groupName and fieldName are present in etc/system.xml file of the module.

PHP Syntax:

Mage::getStoreConfig('sectionName/groupName/fieldName');

From within an editor in the admin, such as the content of a CMS Page or Static Block; the description/short description of a Catalog Category, Catalog Product, etc.

{{config path="sectionName/groupName/fieldName"}}

For the "Within an editor" approach to work, the field value must be passed through a filter for the {{ ... }} contents to be parsed out. Out of the box, Magento will do this for Category and Product descriptions, as well as CMS Pages and Static Blocks. However, if you are outputting the content within your own custom view script and want these variables to be parsed out, you can do so like this:

<?php
    $example = Mage::getModel('identifier/name')->load(1);
    $filter  = Mage::getModel('cms/template_filter');
    echo $filter->filter($example->getData('field'));
?>

Replacing identifier/name with the a appropriate values for the model you are loading, and field with the name of the attribute you want to output, which may contain {{ ... }} occurrences that need to be parsed out.

Magento 2.x

From any Block class that extends \Magento\Framework\View\Element\AbstractBlock

$this->_scopeConfig->getValue('sectionName/groupName/fieldName');

Any other PHP class:

If the class (and none of it's parent's) does not inject \Magento\Framework\App\Config\ScopeConfigInterface via the constructor, you'll have to add it to your class.

// ... Remaining class definition above...

/**
 * @var \Magento\Framework\App\Config\ScopeConfigInterface
 */
protected $_scopeConfig;

/**
 * Constructor
 */
public function __construct(
    \Magento\Framework\App\Config\ScopeConfigInterface $scopeConfig
    // ...any other injected classes the class depends on...
) {
  $this->_scopeConfig = $scopeConfig;
  // Remaining constructor logic...
}

// ...remaining class definition below...

Once you have injected it into your class, you can now fetch store configuration values with the same syntax example given above for block classes.

Note that after modifying any class's __construct() parameter list, you may have to clear your generated classes as well as dependency injection directory: var/generation & var/di