Declaration error during compile

Question

Just update to 2.3.0, use setup:di:compile and get following error:

Warning: Declaration of Iksanika\Productmanage\Model\ResourceModel\Search\Collection::_getSelectCountSql($select = NULL, $resetLeftJoins = true) should be compatible with Magento\Catalog\Model\ResourceModel\Product\Collection::_getSelectCountSql(?Magento\Framework\DB\Select $select = NULL, $resetLeftJoins = true) in /home/server/web/server.dev.vendor.com/public_html/app/c
ode/Iksanika/Productmanage/Model/ResourceModel/Search/Collection.php on line 40

    public function _getSelectCountSql($select = null, $resetLeftJoins = true)
{
    $this->_renderFilters();
    $countSelect = is_null($select) ? $this->_getClearSelect() : $this->_buildClearSelect($select);
    if(count($this->getSelect()->getPart(\Zend_Db_Select::GROUP)) > 0)
    {
        $countSelect->reset(\Zend_Db_Select::GROUP);
        $countSelect->distinct(true);
        $group = $this->getSelect()->getPart(\Zend_Db_Select::GROUP);
        $countSelect->columns("COUNT(DISTINCT ".implode(", ", $group).")");
    } else {
        $countSelect->columns('COUNT(*)');
    }
    return $countSelect;
}

This error appears only on dev server, on local - all ok. How to resolve this error?

Answer 1

Add top of your class:

use Magento\Framework\DB\Select;

Now replace following method:

public function _getSelectCountSql(?Select $select = null, $resetLeftJoins = true)
{
    $this->_renderFilters();
    $countSelect = is_null($select) ? $this->_getClearSelect() : $this->_buildClearSelect($select);
    if(count($this->getSelect()->getPart(\Zend_Db_Select::GROUP)) > 0)
    {
        $countSelect->reset(\Zend_Db_Select::GROUP);
        $countSelect->distinct(true);
        $group = $this->getSelect()->getPart(\Zend_Db_Select::GROUP);
        $countSelect->columns("COUNT(DISTINCT ".implode(", ", $group).")");
    } else {
        $countSelect->columns('COUNT(*)');
    }
    return $countSelect;
}