How to do the server side validation for login form?

Question

I have done client-side validation but how to do the server side validation for the login form.

Answer 1

You can write your custom controller to post data and validate it in execute method when submit.

For example:

<?php
namespace [Vendor]\[Module]\Controller\Account;  

use Magento\Customer\Api\AccountManagementInterface;  

class customPost{
    ...
    protected $customerAccountManagement;
    ...
    public function __construct(
        AccountManagementInterface $customerAccountManagement
    ){
        $this->customerAccountManagement = $customerAccountManagement;
        .....
    }

    public function execute()
    { 
        if ($this->getRequest()->isPost()) {
            $login = $this->getRequest()->getPost('login');
            if (!empty($login['username']) && !empty($login['password'])) {
                try {
                        $customer = $this->customerAccountManagement->authenticate($login['username'], $login['password']);
                        ...
                    }
            }
        }
    }
}

For reference you can check core file:

/var/www/html/magento/vendor/magento/module-customer/Controller/Account/LoginPost.php

Answer 2

You can use plugin for that :

Write the following in your module's app/code/YourNamespace/YourModule/etc/di.xml file:

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\Customer\Controller\Account\LoginPost">
        <plugin name="yourModuleAccountLoginPost" type="YourNamespace\YourModule\Plugin\Customer\LoginPost" sortOrder="10" disabled="false"/>
    </type>
</config>

Create a new file app/code/YourNamespace/YourModule/Plugin/Customer/LoginPost.php and write the following code in it.

<?php

namespace YourNamespace\YourModule\Plugin\Customer;

class LoginPost
{
    public function aroundExecute(\Magento\Customer\Controller\Account\LoginPost $subject, \Closure $proceed)
    {
    // Add your custom code before the original execute function
        $this->doSomethingBeforeExecute(); // call the original execute function
        $returnValue = $proceed();
        // your custom code after the original execute function
        if ($returnValue) { 
            $this->doSomethingAfterExecute();
        }
        return $returnValue;
    }
}
?>