How to Configure Variables in Drupal 8 and Drupal 9

In Drupal 8, Variable_set() and Variable_get() have been deprecated and variables are managed using the config table, replacing the old variables table from Drupal 7.

Configure default variables in Drupal 8/9 by using the following points,

• Create the MODULE.settings.yml file, it allows us to set default values.
• Create the MODULE.schema.yml, it defines the storage type.

This blog explains the basic example of a variable configuration in Drupal 8/9: 

Create the MODULE.settings.yml file:

MODULE/config/install/MODULE.settings.yml is where the setting file should be placed.

variable_one: 'Sample Content'
variable_two: 20
variable_three: true

Create the MODULE.schema.yml file:

MODULE/config/schema/MODULE.schema.yml as the schema. Two different configurations exist. schema config_entity for entities and config_object for global configuration.

module_name.settings:
  type: mapping
  label: Variable Settings of My Module
  mapping:
    variable_one:
      type: string
    variable_two:
      type: integer
    variable_three:
      type: boolean

Get the configured objects:

We can obtain configured variables by using the get() method in Drupal 8 and Drupal 9.

<?php

$get_variable_one = \Drupal::config('module_name.settings')->get('variable_one');
echo $get_variable_one;        // output: Sample Content

$get_variable_two = \Drupal::config('module_name.settings')->get('variable_two');
echo $get_variable_two;        // output: 20

$get_variable_three = \Drupal::config('module_name.settings')->get('variable_three');
echo $get_variable_three;        // output: 1

Edit the configured objects:

We can edit configured variable values by using getEditable() function with the set() method in Drupal 8 and Drupal 9.

<?php
$config = \Drupal::service('config.factory')->getEditable('module_name.settings');
$config->set('variable_one', 'New Value')->set('variable_two', FALSE)->save();

Delete the configured objects:

In Drupal 8 and 9, there are 4 ways to delete a configuration item.

1. Using Drush

   $drush config-delete "module_name.settings"

2.  Using Drupal Console

   $drupal config:delete active "module_name.settings"

3.  Using Devel module

   • Enable the Devel module, go to the /devel/php page or used in any module and execute this: 

     <?php
     \Drupal::configFactory()->getEditable('module_name.settings')->delete();

4. Using Config Delete module

   •  Install and enable the config_delete module, then select what you wish to remove by navigating to Configuration -> Development -> Configuration synchronisation -> Delete, then click the Delete button.