How to use Mage::getModel() on Magento 2?

Question

I need to convert my following Mage::getModel() from Magento1 to Magento2

$cart_api = Mage::getModel('checkout/cart_api');
$quoteId = $cart_api->create($storeObject->getStoreId());
$quote = Mage::getModel('sales/quote')->loadByIdWithoutStore($quoteId);

$product = Mage::getModel('catalog/product');

$customer = Mage::getModel('customer/customer');
$customerAddress = Mage::getModel('customer/address');

$convertQuoteObj = Mage::getModel('sales/convert_quote');

$storeObject = Mage::getModel('core/store')->load(1);

So anyone let me know the correct method for Magento2.

Answer 1

For Mage::getModel magento1 you need to use the below code for Magento 2:

$objectManager = \Magento\Framework\App\ObjectManager::getInstance();
$model = $objectManager->create('\Namespace\Modulename\Model\Modulename');

For Mage::getSingleton you need to use:

$objectManager = \Magento\Framework\App\ObjectManager::getInstance();
$model = $objectManager->get('\Namespace\Modulename\Model\Modulename');

Answer 2

Override constructor in your Model class and add your model class as dependency.

protected $_modelObj;
public function __construct(
    ...
    \Vendor\Example\Model\Model $modelObj,
    ...
) {
      ...
      $this->modelObj = $modelObj;
      ...
}

function someMetod() {
    $model =  $this->modelObj->create();
}

There are thousands of examples you can find in google for same. Also you can check core files how it is implemented.

Adding here one specific answer for your question:

protected $_quoteFactory;

public function __construct(
    ...
    \Magento\Quote\Model\QuoteFactory $quoteFactory
) {
    $this->_quoteFactory = $quoteFactory;
    parent::__construct(...);
}

Then in your class you can do:

$this->_quoteFactory->create()->loadByIdWithoutStore($quoteId);

For using it in your custom class, check this link!

Hope this helps!

<?php

namespace Yourcompany\<yourmodule>\Helper {

/**
 * Customer data helper
 */
class Data extends \Magento\Framework\App\Helper\AbstractHelper
{
    protected $customerRepository;

    public function __construct(
        \Magento\Customer\Api\CustomerRepositoryInterfaceFactory $customerRepositoryFactory) {
        $this->customerRepository = $customerRepositoryFactory->create();
    }

    public LoadCustomerById($customerId) {
         $customer = $this->customerRepository->getById($customerId);
         return $customer;
    } 

}

Same way you can add functions for getting product detail and use these in your module controller. Hope this helps!