Yii2 创建数据库连接

I want to create a database connection programmatically without using the config file. I have a form wherein the user enters the database details like the hostname, username, password and the database name. On the basis of these details a new test connection is made and if it passes it should generate the necessary files. This is what I have tried:

// Create Test DB Connection
Yii::$app->set('id', [
                    'class'    => 'yiidbConnection',
                    'dsn'      => $dsn,
                    'username' => $form->username,
                    'password' => $form->password,
                    'charset'  => 'utf8'
                ]);
try {
    // Check DB Connection
    if (Yii::$app->db->getIsActive()) {
       // Write Config
        $config['components']['db']['class']    = 'yiidbConnection';
        $config['components']['db']['dsn']      = $dsn;
        $config['components']['db']['username'] = $username;
        $config['components']['db']['password'] = $password;
        $config['components']['db']['charset']  = 'utf8';

        Configuration::setConfig($config);
        $success = TRUE;
        return $this->redirect(['init']);
    }else{
        $errorMsg = 'Incorrect Configurations';
    }
} catch (Exception $e) {
        $errorMsg = $e->getMessage();
}

我一次又一次地对此进行了测试，即使配置正确，它也会出现错误.感谢所有的帮助.提前致谢！