Module uninstallation does not remove configuration

Question

I have my own module installed via composer and I can uninstall it with

php bin/magento module:uninstall XXX_XXX

But when I reinstall the module the configuration (values in system.xml) is still the same as it was setup while it was installed before. Do I have to remove the configurations manually? How?

EDIT: My current Uninstall class:

<?php
namespace XXXX\XXXXX\Setup;
use Magento\Framework\Setup\UninstallInterface;
use Magento\Framework\Setup\SchemaSetupInterface;
use Magento\Framework\Setup\ModuleContextInterface;
 class Uninstall implements UninstallInterface
 {
 public function uninstall(SchemaSetupInterface $setup, ModuleContextInterface $context) {
 $setup->startSetup();
 $connection = $setup->getConnection();
 $connection->dropTable($connection->getTableName('mytable_data'));
 $setup->endSetup();
 }
 }

Answer 1

The uninstall-command actually only removes anything when you invoke it with --remove-data and your module has an Uninstall class that implements Magento\Framework\Setup\UninstallInterface. I believe if you want to remove configuration values, you can also do this here.

The official documentation is a place to start: http://devdocs.magento.com/guides/v2.0/install-gde/install/cli/install-cli-uninstall-mods.html

EDIT

As far as I can see, the Uninstall class does not have access to the configuration by default, so you should define an own constructor to fix this. Code is shortened and untested:

<?php
class Uninstall implements UninstallInterface
{
 /**
 * @var \Magento\Framework\App\Config\ConfigResource\ConfigInterface
 */
 protected $resourceConfig;
 public function __construct( 
 \Magento\Framework\App\Config\ConfigResource\ConfigInterface $resourceConfig
 ) {
 $this->resourceConfig = $resourceConfig;
 }
 ...
}

Then, in your uninstall()-function, use that interface's deleteConfig() method to delete your configuration:

$this->resourceConfig->deleteConfig(
 'my/config_path',
 \Magento\Framework\App\Config\ScopeConfigInterface::SCOPE_TYPE_DEFAULT, 
 \Magento\Store\Model\Store::DEFAULT_STORE_ID
);

• alobeejay: I have an Uninstall Class in my module and the commands in there are getting called when uninstalling. But I am not doing anything manually with the configuration in there. Does that mean I have to remove the normal configuration data by hand in the Uninstall file? How do I do that?
• simonthesorcerer: Can you post your code?
• alobeejay: I don't have any code that deletes the configuration. That is what I need.
• simonthesorcerer: Can you please share your uninstall class?
• alobeejay: Sure. I edited my post above.