Drupal 8 - How to switch to external database in custom module?

Question

I am trying to switch to and query a external database in a custom Drupal 8 module I have created.

I have added the external database below the native database in settings.php :

// Add second database

$databases['external']['default'] = array(
  'database' => 'uconomy_external',
  'username' => 'uconomy_admin',
  'password' => 'fNjA9kC35h8',
  'prefix' => '',
  'host' => 'localhost',
  'port' => '3306',
  'namespace' => 'Drupal\\Core\\Database\\Driver\\mysql',
  'driver' => 'mysql',
);

I then have a file named BusinessListingDbLogic.php where I make queries to the database :

<?php

namespace Drupal\business_listing;

use Drupal\Core\Database\Connection;
use Drupal\Core\Database\Database;

/**
* Defines a storage handler class that handles the node grants system.
*
* This is used to build node query access.
* 
* This class contains all the logic for interacting with our database 
* 
* @ingroup business_listing
*/
class BusinessListingDbLogic {

 /**
  * @var \Drupal\Core\Database\Connection
  */   
 protected $database;

     /**
     * @param \Drupal\Core\Database\Connection $connection
     */
 public function __construct(Connection $connection) {

   $this->database = $connection;
   //Database::setActiveConnection('external');

 }

 /**
  * Add new record in table business_listing.
  */
 public function add($title, $body, $imageName, $location, $email) {
   if (empty($title) || empty($body) || empty($imageName) || empty($location) || empty($email)) {
    return FALSE;
   }
   // add record to business_listing table in database.
   $query = $this->database->insert('business_listing');
   $query->fields(array(
    'title' => $title,
    'body' => $body,
    'image' => $imageName,
    'location' => $location,
    'email' => $email
   ));
   return $query->execute();
 }

I believe my BusinessListingDbLogic class is registered as a service, my business_listing.services.yml looks as follows:

 services:
 # Service Name.
 business_listing.database.external:
   class: Drupal\Core\Database\Connection
   factory: 'Drupal\Core\Database\Database::getConnection'
   arguments: ['external']

 # external database dependent serivce.
 business_listing.db_logic:
   # Class that renders the service.
   # BusinessListingDbLogic contains all the functions we use to interact with the business_listings table
   class: Drupal\business_listing\BusinessListingDbLogic
   # Arguments that will come to the class constructor.
   arguments: ['@business_listing.database.external']
   # A more detailed explanation: https://www.drupal.org/node/2239393.
#   tags:
#    - { name: backend_overridable }

This code works until I try uncomment Database::setActiveConnection('external'); I then get the following error:

The website encountered an unexpected error. Please try again later.Drupal\\Core\\Database\\DatabaseExceptionWrapper: SQLSTATE[42S02]: Base table or view not found: 1146 Table 'uconomy_external.shortcut_set_users' doesn't exist: SELECT ssu.set_name AS set_name FROM {shortcut_set_users} ssu WHERE ssu.uid = :db_condition_placeholder_0; Array ( [:db_condition_placeholder_0] => 1 )

it looks like the switch is working, but Drupal might be trying to use the external database for its native functionality? I know I also have to switch back to the default database at some point, but I am not sure where to do this?

Any help or advice would be GREATLY appreciate. Kind Regards, Matt

Answer 1

Seems that instead of calling your current connection to set, you need to use the static method Database::setActiveConnection() directly.

Eg. $this->database->setActiveConnection('external') becomes Database::setActiveConnection('external')