Class 'yii\app\models\DB' not found in yii2 - database

Question

I am trying to use database connection inside my model but it was not getting connected throwing error as "Class 'app\models\DB' not found". I have created a common model to be extended by all my models inside modules that means all models extends the CommonModel, I am getting this error inside the CommonModel. I have read yii documentation regards database connection & googled for the same but I din't find any solution. My code is:
models\CommonModel.php
namespace app\models;
use Yii;
use yii\base\NotSupportedException;
use yii\db\ActiveRecord;
use yii\helpers\Security;
use yii\web\IdentityInterface;
use yii\db\Query;
use app\models\Mailsettings;
use \PDO as PDO;
class CommonModel extends \yii\db\ActiveRecord{
protected $_db;
protected $_sql;
public function __construct()
{
$this->_db = DB::init(); // This line causing the error
$pdo = Timetrackdb::getPdoConnection();
}
----
----
}
config/db.php & config/db2.php
return [
'class' => 'yii\db\Connection',
'dsn' => 'mysql:host=localhost;dbname=my_db_name',
'username' => 'db_username',
'password' => 'db_password',
'charset' => 'utf8',
];
config/web.php
$db = require __DIR__ . '/db.php';
$db2 = require __DIR__ . '/db2.php';
$config = [
'id' => 'basic',
'basePath' => dirname(__DIR__),
'bootstrap' => ['log'],
'modules' => [
'my_module1' => [
'class' => 'app\modules\my_module1'
],
'my_module2' => [
'class' => 'app\modules\my_module2'
],
],
------
------
'db' => $db,
'db2' => $db2,
------
------
];
I have created 2 modules in which one module is working fine with the same type of database connection but the other module's db connection is not working properly. Can anyone please tell whats wrong with this code? Thanks.

Answer 1

Yii deals with connecting to databases for you, you don't need PDO. Just access Yii::$app->db2 if you want to have CommonModel or derived ActiveRecord classes to use the second database as their data store:
class CommonModel extends ActiveRecord {
public static function getDb()
{
// this will cause Yii to use the database configured as 'db2' in config/web.php
return Yii::$app->db2;
}
}
class Car extends CommonModel { }
// will try to insert a new row in `db2`.`car`
(new Car)->save();
You may also need to do the following if you're going to perform cross-schema queries (config/db2.php):
return [
// ...
// add and adjust the keys below
'tablePrefix' => '',
'schemaMap' => [
'mysql' => [
'class' => 'yii\db\mysql\Schema',
'defaultSchema' => 'my_db_name',
],
],
];