Magento 2 : Only dependency assignment operations are allowed in constructor. No other operations are allowed

Question

Magento 2 Coding standard provide me Warning

My Code is here

namespace Namespace\Modulename\Model;

use Magento\Framework\App\Request\DataPersistorInterface;
use Magento\Ui\DataProvider\AbstractDataProvider;
use Namespace\Modulename\Model\ResourceModel\Customoption\CollectionFactory;

class CustomoptionProvider extends AbstractDataProvider
{
    public $collection;
    public $dataPersistor;
    public $loadedData;

    public function __construct(
        $name,
        $primaryFieldName,
        $requestFieldName,
        CollectionFactory $pageCollectionFactory,
        DataPersistorInterface $dataPersistor,
        array $meta = [],
        array $data = []
    ) {
        $this->collection    = $pageCollectionFactory->create();
        $this->dataPersistor = $dataPersistor;
        parent::__construct($name, $primaryFieldName, $requestFieldName, $meta, $data);
    }

    public function getData()
    {
        if (isset($this->loadedData)) {
            return $this->loadedData;
        }
        $items = $this->collection->getItems();
        foreach ($items as $page) {
            ...
        }
        $data = $this->dataPersistor->get('module_messages');
        if (!empty($data)) {
            $page = $this->collection->getNewEmptyItem();
            $page->setData($data);
            $this->loadedData[$page->getId()] = $page->getData();
            $this->dataPersistor->clear('module_messages');
        }
        return $this->loadedData;
    }
}

I had use this

$this->collection = $pageCollectionFactory;

$this->collection = $this->collection->create();

but it provide me error

Fatal error: Method Magento\Ui\TemplateEngine\Xhtml\Result::__toString() must not throw an exception, caught Error: Call to undefined method Namespace\Modulename\Model\ResourceModel\Customoption\CollectionFactory::addFieldToFilter() in D:\xampp72\htdocs\mage231\vendor\magento\module-ui\Component\Wrapper\UiComponent.php on line 0

if have any solution then provide for this issue.

Answer 1

Add this member to your class

protected $collectionFactory;

In your constructor add this

$this->collectionFactory = $pageCollectionFactory;

and remove this

$this->collection    = $pageCollectionFactory->create();

then add this method

public function getCollection()
{
    if ($this->collection === null) {
        $this->collection = $this->collectionFactory->create();
    }
    return $this->collection;
}