Switch database dynamically in Codeigniter 3.x - codeigniter

Question

In a required scenario, I want to switch to OTHER database dynamically depending on the domain name. I have database-1 in which there is table-1 which stores the hostname, dbname, username and password of the other databases that I need to select and connect dynamically.
I have enabled the 'database' library in autoload.php with the credentials of database-1 in database.php so that when the controller is called, it will check if the OTHER database credentials are already available (in session or some other safezone). If yes, then models will use the already available OTHER database credentials, otherwise SELECT query should be fired on database-1 to fetch the OTHER database credentials and then the models should use the OTHER database credentials.
I have two issues in my implementation:
I don't know the condition where to store and check OTHER database credentials availability. If I save it in a session, OTHER db credentials might be hacked by session hijacking. Also the credentials will be fetched again and again for every visitor of a domain.
CI does not reconfigure the 'database' library or 'models' to work on fetched OTHER database credentials, it still uses the autoloaded database-1 credentials from database.php.
$this->load->model('otherdb');
$otherconfig=$this->otherdb->getotherdb(base_url());
$config=array();
if(isset($otherconfig) && !empty($otherconfig)){
$config['hostname'] = $otherconfig->host;
$config['username'] = $otherconfig->user;
$config['password'] = $otherconfig->pass;
$config['database'] = $otherconfig->nameofdb;
$config['dbdriver'] = 'mysqli';
$config['dbprefix'] = '';
$config['pconnect'] = FALSE;
$config['db_debug'] = TRUE;
}
$this->load->database($config); //doesnt work, still uses old DB
$this->load->model('model1','',$config); //doesnt work, still uses old DB
$this->load->model("model2",'',$config); //doesnt work, still uses old DB
$this->load->model('model3','',$config); //doesnt work, still uses old DB

Answer 1

Connect to the database in your Model rather than in the controller, below approach allows you to use 2 database at the same time. It also helps to keep the database stuff in the model and the controller clear of it.
in your controller, remove the config settings and just load the model like:
$this->load->model('Model1');
$this->Model1->getdata(); // call a function in your model
then in your model you do the db configuration
class Model1 extends CI_Model {
function __construct()
{
parent::__construct();
$otherconfig=$this->getotherdb(base_url());
$config=array();
if(isset($otherconfig) && !empty($otherconfig)){
$config['hostname'] = $otherconfig->host;
$config['username'] = $otherconfig->user;
$config['password'] = $otherconfig->pass;
$config['database'] = $otherconfig->nameofdb;
$config['dbdriver'] = 'mysqli';
$config['dbprefix'] = '';
$config['pconnect'] = FALSE;
$config['db_debug'] = TRUE;
$this->db2=$this->load->database($config, true);
$this->db=$this->load->database('', true); //load the 'default' database as defined in your config/database.php
}
function getdata()
{
$db2->query();
$db2->result();
}
function getotherdb($base_url)
{
// get your database credentials
// you can still use the autoloaded db
$db->query();
$db->result();
}
}
from the docs: Connecting to Multiple Databases

Answer 2

Depending on what you want to do the application of the logic may be different but with that being said you can configure multiple Database connections in CI in your database.php file.
$db['default'] = array(
'dsn' => '',
'hostname' => 'localhost',
'username' => 'root',
'password' => '',
'database' => 'mydatabase',
'dbdriver' => 'mysqli',
'dbprefix' => '',
'pconnect' => TRUE,
'db_debug' => (ENVIRONMENT !== 'production'),
'cache_on' => FALSE,
'cachedir' => '',
'char_set' => 'utf8',
'dbcollat' => 'utf8_general_ci',
'swap_pre' => '',
'encrypt' => FALSE,
'compress' => FALSE,
'stricton' => FALSE,
'failover' => array(),
'save_queries' => TRUE
);
$db['second'] = array(
'dsn' => '',
'hostname' => 'localhost',
'username' => 'root',
'password' => '',
'database' => 'mydatabase',
'dbdriver' => 'mysqli',
'dbprefix' => '',
'pconnect' => TRUE,
'db_debug' => (ENVIRONMENT !== 'production'),
'cache_on' => FALSE,
'cachedir' => '',
'char_set' => 'utf8',
'dbcollat' => 'utf8_general_ci',
'swap_pre' => '',
'encrypt' => FALSE,
'compress' => FALSE,
'stricton' => FALSE,
'failover' => array(),
'save_queries' => TRUE
);
To use the second database connection in your controllers you can simply select it using this:
private $db2;
function __construct(){
parent::__construct();
$db2 = $this->load->database('second', TRUE);
// YOU NEED TO ADD TRUE AS THE SECOND PARAMETER TO LOAD THE DB OBJECT
}
public function Users(){
$query = $this->db2->get('TABLE_NAME');
return $query->result_array();
}
If you are loading the database configuration from an initial DB this can still be done, don't forget that codeigniter is still PHP.
The $db[] array can be created dynamically using logic, you could create a json file that stores such information and populate the db array with it.