Php how to implement database multi-tenancy (YII2)

yii2_database_tenancy

<?php

/*
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 */

namespace app\assets;

define("TENANT_SESSION_KEY", "tenant_session_key");

/**
 * Description of TenancyAsset
 *
 * @author uchep
 */
class TenancyAsset {

    /*
     * How to enable tenancy
     * Replace getDb() in the \yii\base\Application with the code below
     * 
     * public function getDb() {
        $b = $this->get('db');
        $dbName = \app\assets\TenancyAsset::getDatabaseName();
        $b->dsn = str_replace('db_name', $dbName, $b->dsn);
        return $b;
    }
     */
    
    /**
     * this function should get data of the merchant from the whatever service is provided
     * @return type
     */
    private static function getTenantLiveDetails() {
        return['database_name' => 'cuorma'];
    }

    /**
     * this set the merchant detail in the sesssion
     * @param type $tenantDetails
     */
    private static function setTenantSession($tenantDetails) {
        \Yii::$app->session->set(TENANT_SESSION_KEY, $tenantDetails);
    }

    /**
     * get merchant details from session
     * 
     * @return type
     */
    private static function getTenantSession() {
        return \Yii::$app->session->get(TENANT_SESSION_KEY);
    }

    /**
     * 
     * this functions gets the merchant data by returning the merchant detail from session of available
     * if not, it will try to get the data from the service, if also not available, it throws  NotFoundHttpException 
     * 
     * this function was created as a test of the DB tenancy architecture
     * 
     * @return type
     * @throws NotFoundHttpException
     */
    public static function accessTenantData() {
        $st = TenancyAsset::getTenantSession();
        if (isset($st)) {
            TenancyAsset::setTenantSession($st);
        } else {
            $st = TenancyAsset::getTenantLiveDetails();
            if (isset($st)) {
                TenancyAsset::setTenantSession($st);
            } else {
                throw new NotFoundHttpException('UNKNOWN MERCHANT');
            }
        }
        return $st;
    }

    public static function getDatabaseName() {
        $st = TenancyAsset::accessTenantData();
        if (isset($st)) {
            return $st['database_name'];
        }
        return null;
    }

}