What is alternative for cacheable="false"?

Question

If I used cacheable="false"in my custom module layout file then I get customer id by using when all type of cache is enabled.

public function _construct(
    \Magento\Customer\Model\Session $session
) {
    $this->customerSession = $session;
}
public function abc()
{
    if ($this->customerSession->isLoggedIn()) {
        echo $this->customerSession->getCustomerId();
    }
}

But when I upload module in the marketplace then it rejected because of cacheable="false" so what is alternative way of cacheable="false"to get customer id in the frontend.

Answer 1

Please use this code for your construct method.

public function _construct(
    \Magento\Customer\Model\Session $session
) {
    $this->_isScopePrivate = true;
    $this->customerSession = $session;
}
public function abc()
{
    if ($this->customerSession->isLoggedIn()) {
        echo $this->customerSession->getCustomerId();
    }
}

Answer 2

Use model factory instead of model class

public function _construct(
    \Magento\Customer\Model\SessionFactory $sessionFactory
    ){
         $this->customerSessionFactory = $sessionFactory;
    }
    public function abc(){
        $customerSession  = $this->customerSessionFactory->create();
        if($customerSession->getCustomer()->getId()){
            return $customerSession->getCustomer()->getId();
        }
    }

Answer 3

One needs to implement Private Content mechanism as described in magento official documentation here :

https://devdocs.magento.com/guides/v2.4/extension-dev-guide/cache/page-caching/private-content.html