Issue¶
How do I connect to a database outside of Drupal?
Resolution¶
There are steps listed out in this Drupal.org page:
https://www.drupal.org/docs/7/creating-custom-modules/howtos/how-to-connect-to-multiple-databases-within-drupal
In short:¶
- Define the secondary Database in your "settings.php",
- Switch to the Database inside of your module,
- Query that database,
- Swap back to the default Database when finished.
Detailed example¶
The following is an example of changing between the default Drupal database and a second, additional, database in a custom module, to query the second one.
1. Define the secondary Database in your "settings.php"The file,
https://api.drupal.org/api/drupal/sites%21default%21default.settings.php/10 , under the "
View Source" section, defines the format for the
$databases variable.
Essentially, the first key is the database name and the second key is used as a replication database name, or a "target" name, if you wish to use primary/replica database replication for your site.
$databases['database_name']['database_target']
If you are wanting to access a different database, in addition to your Drupal database, then use the first key name for the
$databases variable.
For example, the following code snippet defines the configurations for the default Drupal database and an additional database, named "
second_db". Note the keys used for the
$databases variable.
// Default Drupal database configuration
$databases['default']['default'] = array (
'database' => 'drupal',
'username' => 'drupal',
'password' => 'drupal',
'prefix' => '',
'host' => 'localhost',
'port' => '3306',
'isolation_level' => 'READ COMMITTED',
'driver' => 'mysql',
'namespace' => 'Drupal\\mysql\\Driver\\Database\\mysql',
'autoload' => 'core/modules/mysql/src/Driver/Database/mysql/',
);
// Second database configuration
$databases['second']['default'] = array(
'database' => 'second_db',
'username' => 'drupal',
'password' => 'drupal',
'host' => 'localhost',
'port' => '3306',
'namespace' => 'Drupal\\Core\\Database\\Driver\\mysql',
'driver' => 'mysql',
'prefix' => '',
);
See further details, for the database configuration definitions, in the following Drupal documentation pages:
2. Switch to the Database inside of your moduleSwitch to the additional database by using the
Database::setActiveConnection() and
Database::getConnection() static methods.
For the example presented here, this would be a call such as:
// Change the active connection to the additional database
Database::setActiveConnection('second');
// Get the database connection for the additional database
$second_db_conn = Database::getConnection();
Perform the query to the database that is not the default Drupal database.
// Execute a query on tables in the additional database
$result = $second_db_conn->select('some_table', 't')
->fields('t', ['id', 'column_name'])
->range(0, 1)
->execute()
->fetchAll();
// Do something with the result
// ...
Change the connection back to the default Drupal database connection.
// Switch back to the default Drupal database.
Database::setActiveConnection();
That's it, you have successfully implemented a change between your default Drupal database and an additional one!