How to Create Controller in Magento 2?

Controllers in Magento 2, like on other PHP MVC frameworks, are important part of MVC flow. In Magento 2 controllers have only one method (execute) that will be called by front controller. It functionality is that received request, process and render page. In Magento 2 Controller has one or more files in Controller folder of module, it includes actions of class which contain execute() method.

There are 2 different controllers, they are frontend controller and backend controller.

Difference between admin and front controller : Main difference between these two controllers is in additional check and additional methods in admin controller. Both controllers eventually extend \Magento\Framework\App\Action\Action class, but admin controller extend \Magento\Backend\App\Action class, which extends \Magento\Framework\App\Action\Action. Both are generally similar of workflow, but admin controller is a little different. There is a checking permission method in admin controller, it calls form key.

How controller work? www.example.com/route_name/controller/action

route_name is a unique name which is set in routes.xml.
controller is the folder inside Controller folder.
action is a class with execute method to process request.

Step 1 : Create routes.xml file.

File Path : app/code/V4U/Helloworld/etc/frontend/routes.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../../lib/internal/Magento/Framework/App/etc/routes.xsd">
    <router id="standard">
        <route id="helloworld" frontName="helloworld">
            <module name="V4U_Helloworld"/>
        </route>
    </router>
</config>

<?xml version="1.0"?>

</route>

</router>

</config>

Step 2: Create controller file

File Path : app/code/V4U/Helloworld/Controller/Index/Index.php

<?php

namespace V4U\Helloworld\Controller\Index;

use Magento\Framework\App\Action\Action;
use Magento\Framework\App\Action\Context;
use Magento\Framework\App\RequestInterface;
use Magento\Framework\View\Result\PageFactory;

class Index extends Action
{
    /**
     * The PageFactory to render with.
     *
     * @var PageFactory
     */
    protected $_resultsPageFactory;

    /**
     * Set the Context and Result Page Factory from DI.
     * @param Context     $context
     * @param PageFactory $resultPageFactory
     */
    public function __construct(
        Context $context,
        PageFactory $resultPageFactory
    ) {
        $this->_resultsPageFactory = $resultPageFactory;
        parent::__construct($context);
    }

    /**
     * Show the Hello World Index Page.
     *
     * @return \Magento\Framework\View\Result\Page
     */
    public function execute() {
        return $this->_resultsPageFactory->create();
    }
}

<?php

namespace V4U\Helloworld\Controller\Index;

use Magento\Framework\App\Action\Action;

use Magento\Framework\App\Action\Context;

use Magento\Framework\App\RequestInterface;

use Magento\Framework\View\Result\PageFactory;

class Index extends Action

{

/**

* The PageFactory to render with.

* @var PageFactory

protected $_resultsPageFactory;

/**

* Set the Context and Result Page Factory from DI.

* @param Context $context

* @param PageFactory $resultPageFactory

public function __construct(

Context $context,

PageFactory $resultPageFactory

) {

$this->_resultsPageFactory = $resultPageFactory;

parent::__construct($context);

}

/**

* Show the Hello World Index Page.

* @return \Magento\Framework\View\Result\Page

public function execute() {

return $this->_resultsPageFactory->create();

}

Step 3: Create Layout file

File Path : app/code/V4U/Helloworld/view/frontend/layout/helloworld_index_index.xml