Tasks.php

1. 8.x drupal/core/lib/Drupal/Core/Database/Install/Tasks.php
2. 8.x drupal/core/lib/Drupal/Core/Database/Driver/sqlite/Install/Tasks.php
3. 8.x drupal/core/lib/Drupal/Core/Database/Driver/mysql/Install/Tasks.php
4. 8.x drupal/core/lib/Drupal/Core/Database/Driver/pgsql/Install/Tasks.php

<?php

/**
 * @file
 * Definition of Drupal\Core\Database\Driver\mysql\Install\Tasks
 */
namespace Drupal\Core\Database\Driver\mysql\Install;

use Drupal\Core\Database\Install\Tasks as InstallTasks;
use Drupal\Core\Database\Database;
use Drupal\Core\Database\Driver\mysql\Connection;
use Drupal\Core\Database\DatabaseNotFoundException;

/**
 * Specifies installation tasks for MySQL and equivalent databases.
 */
class Tasks extends InstallTasks {

  /**
   * The PDO driver name for MySQL and equivalent databases.
   *
   * @var string
   */
  protected $pdoDriver = 'mysql';

  /**
   * Returns a human-readable name string for MySQL and equivalent databases.
   */
  public function name() {
    return st('MySQL, MariaDB, or equivalent');
  }

  /**
   * Returns the minimum version for MySQL.
   */
  public function minimumVersion() {
    return '5.0.15';
  }

  /**
   * Check database connection and attempt to create database if the database is
   * missing.
   */
  protected function connect() {
    try {

      // This doesn't actually test the connection.
      db_set_active();

      // Now actually do a check.
      Database::getConnection();
      $this
        ->pass('Drupal can CONNECT to the database ok.');
    } catch (\Exception $e) {

      // Attempt to create the database if it is not found.
      if ($e
        ->getCode() == Connection::DATABASE_NOT_FOUND) {

        // Remove the database string from connection info.
        $connection_info = Database::getConnectionInfo();
        $database = $connection_info['default']['database'];
        unset($connection_info['default']['database']);

        // In order to change the Database::$databaseInfo array, need to remove
        // the active connection, then re-add it with the new info.
        Database::removeConnection('default');
        Database::addConnectionInfo('default', 'default', $connection_info['default']);
        try {

          // Now, attempt the connection again; if it's successful, attempt to
          // create the database.
          Database::getConnection()
            ->createDatabase($database);
        } catch (DatabaseNotFoundException $e) {

          // Still no dice; probably a permission issue. Raise the error to the
          // installer.
          $this
            ->fail(st('Database %database not found. The server reports the following message when attempting to create the database: %error.', array(
            '%database' => $database,
            '%error' => $e
              ->getMessage(),
          )));
        }
      }
      else {

        // Database connection failed for some other reason than the database
        // not existing.
        $this
          ->fail(st('Failed to connect to your database server. The server reports the following message: %error.<ul><li>Is the database server running?</li><li>Does the database exist or does the database user have sufficient privileges to create the database?</li><li>Have you entered the correct database name?</li><li>Have you entered the correct username and password?</li><li>Have you entered the correct database hostname?</li></ul>', array(
          '%error' => $e
            ->getMessage(),
        )));
        return FALSE;
      }
    }
    return TRUE;
  }

}