Skip to content

Config Factory & Reading Config

When to Use

When you need to read configuration values in custom code — forms, controllers, services, hooks.

Steps

  1. Choose read method — Immutable (config()) or editable (getEditable())
  2. Inject ConfigFactory — Via dependency injection in services
  3. Get config object — $config = $this->configFactory->get('module.settings');
  4. Read values — $value = $config->get('key'); or $all = $config->get();
  5. Handle nested keys — Use dot notation: $config->get('parent.child.key')
  6. Check for overrides — $config->hasOverrides('key') if needed
  7. Get original values — $config->getOriginal('key', FALSE) for override-free value

Example: Reading Config in Service

namespace Drupal\mymodule\Service;

use Drupal\Core\Config\ConfigFactoryInterface;

class MyService {

  protected ConfigFactoryInterface $configFactory;

  public function __construct(ConfigFactoryInterface $config_factory) {
    $this->configFactory = $config_factory;
  }

  public function doSomething() {
    // Read config (immutable)
    $config = $this->configFactory->get('mymodule.settings');
    $api_key = $config->get('api_key');
    $enabled = $config->get('enabled');

    // All values
    $all = $config->get();

    // Nested keys
    $timeout = $config->get('api.timeout');
  }
}

Example: Editing Config

// Get editable config
$config = \Drupal::service('config.factory')->getEditable('mymodule.settings');

// Set single value
$config->set('api_key', 'new_value');

// Set nested value
$config->set('api.timeout', 30);

// Clear value
$config->clear('old_key');

// Save changes
$config->save();

// Chain methods
$config->set('key1', 'value1')
  ->set('key2', 'value2')
  ->save();

Reference: /core/lib/Drupal/Core/Config/ConfigFactory.php, /core/lib/Drupal/Core/Config/ConfigFactoryInterface.php

Decision Points

At this step... If... Then...
Choosing access method Read-only access Use $this->configFactory->get() (ImmutableConfig)
Choosing access method Need to modify Use $this->configFactory->getEditable() (Config)
In service/controller Proper DI Inject ConfigFactoryInterface in constructor
In procedural code No DI available Use \Drupal::config() or \Drupal::service('config.factory')
After modifications Changes need persistence Call ->save()

Common Mistakes

  • Using \Drupal::config() in classes — Inject ConfigFactoryInterface instead
  • Calling set() on immutable config — Use getEditable() first
  • Forgetting to call save() — Changes are in memory only, not persisted
  • Hardcoding config names — Use constants or derive from entity type
  • Not checking if config exists — get() returns NULL for missing keys, check first
  • Accessing overridden config for comparison — Use getOriginal() for unmodified values

See Also