Magento 2 model error after updating on 2.2 verison

Question

I have a CRUD module created on magento 2.1.6 version which was working ok untill i updated magento to version 2.2.1

Now when i compile my code i receive the following err:

namespace\module\Model\ResourceModel\Post\Grid\Collection
Incompatible argument type: Required type: \Magento\Framework\DB\Adapter\AdapterInterface. Actual type: \namespace\module\Model\ResourceModel\Post\Grid\connection; File:
/data/web/public/app/code/namespace/module/Model/ResourceModel/Post/Grid/Collection.php

so my constructor looks like this before i made any changes:

 public function __construct(
        \Magento\Framework\Data\Collection\EntityFactoryInterface $entityFactory,
        \Psr\Log\LoggerInterface $logger,
        \Magento\Framework\Data\Collection\Db\FetchStrategyInterface $fetchStrategy,
        \Magento\Framework\Event\ManagerInterface $eventManager,
        $mainTable,
        $eventPrefix,
        $eventObject,
        $resourceModel,
        $model = 'Magento\Framework\View\Element\UiComponent\DataProvider\Document',
        $connection = null,
        \Magento\Framework\Model\ResourceModel\Db\AbstractDb $resource = null
    )
    {
        parent::__construct($entityFactory, $logger, $fetchStrategy, $eventManager, $connection, $resource);
        $this->_eventPrefix = $eventPrefix;
        $this->_eventObject = $eventObject;
        $this->_init($model, $resourceModel);
        $this->setMainTable($mainTable);
    }

after i changed the constructor according to the compile error my constructor looks like this:

public function __construct(
        \Magento\Framework\Data\Collection\EntityFactoryInterface $entityFactory,
        \Psr\Log\LoggerInterface $logger,
        \Magento\Framework\Data\Collection\Db\FetchStrategyInterface $fetchStrategy,
        \Magento\Framework\Event\ManagerInterface $eventManager,
        \Magento\Framework\DB\Adapter\AdapterInterface  $connection = null,
        $mainTable,
        $eventPrefix,
        $eventObject,
        $resourceModel,
        $model = 'Magento\Framework\View\Element\UiComponent\DataProvider\Document',

        \Magento\Framework\Model\ResourceModel\Db\AbstractDb $resource = null
    )
    {
        parent::__construct($entityFactory, $logger, $fetchStrategy, $eventManager, $connection, $resource);
        $this->_eventPrefix = $eventPrefix;
        $this->_eventObject = $eventObject;
        $this->_init($model, $resourceModel);
        $this->setMainTable($mainTable);
    }

Now when i compile the code i don't have any err, but when i tried to access my "module menu" i receive this err:

PHP message: PHP Fatal error:  Method Magento\Ui\TemplateEngine\Xhtml\Result::__toString() must not throw an exception, caught Error: Cannot instantiate interface Magento\Framework\DB\Adapter\AdapterInterface

IT said that "Magento\Framework\DB\Adapter\AdapterInterface" can't be instantiate, even the compile was asking for this.

Does anyone have any idea how to solve this problem?

Answer 1

You need to use \Magento\Framework\DB\Adapter\AdapterInterface $connection = null instead of $connection = null

Now your final constructor look like below,

public function __construct(
    \Magento\Framework\Data\Collection\EntityFactoryInterface $entityFactory,
    \Psr\Log\LoggerInterface $logger,
    \Magento\Framework\Data\Collection\Db\FetchStrategyInterface $fetchStrategy,
    \Magento\Framework\Event\ManagerInterface $eventManager,
    $mainTable,
    $eventPrefix,
    $eventObject,
    $resourceModel,
    $model = 'Magento\Framework\View\Element\UiComponent\DataProvider\Document',
    \Magento\Framework\DB\Adapter\AdapterInterface $connection = null,
    \Magento\Framework\Model\ResourceModel\Db\AbstractDb $resource = null
)
{
    parent::__construct($entityFactory, $logger, $fetchStrategy, $eventManager, $connection, $resource);
    $this->_eventPrefix = $eventPrefix;
    $this->_eventObject = $eventObject;
    $this->_init($model, $resourceModel);
    $this->setMainTable($mainTable);
}

Now you can use php bin/magento setup:di:compile your error will gone.