join() is not working

Question

I am trying to show data of order/sales by country into admin grid, so I am joining two tables sales_order_grid and sales_order_address in my Collection.php

Here is my code

 use Magento\Framework\Data\Collection\Db\FetchStrategyInterface as FetchStrategy;
 use Magento\Framework\Data\Collection\EntityFactoryInterface as EntityFactory;
 use Magento\Framework\Event\ManagerInterface as EventManager;
 use Magento\Eav\Model\Entity\Collection\AbstractCollection;
 use Psr\Log\LoggerInterface as Logger;
 use Magento\Framework\App\ResourceConnection;

 class Collection extends \Magento\Sales\Model\ResourceModel\Order\Grid\Collection 
{
protected $_resource;
/**
 * Initialize dependencies.
 *
 * @param EntityFactory $entityFactory
 * @param Logger $logger
 * @param FetchStrategy $fetchStrategy
 * @param EventManager $eventManager
 * @param string $mainTable
 * @param string $resourceModel
 */
public function __construct(
    EntityFactory $entityFactory,
    Logger $logger,
    AbstractCollection $_resource,
    FetchStrategy $fetchStrategy,
    EventManager $eventManager,
    $mainTable = 'sales_order_grid',
    $resourceModel = \Magento\Sales\Model\ResourceModel\Order::class
) {
    parent::__construct($entityFactory, $logger, $fetchStrategy, $eventManager, $mainTable, $resourceModel);
    $this->_resource = $_resource;
}

/**
 * @inheritdoc
 */
protected function _initSelect()
{
    parent::_initSelect();

    $tableDescription = $this->getConnection()->describeTable($this->getMainTable());
    $tableDescription->addAttributeToSelect('*');
    $joinConditions = 'e.customer_id = s.customer_id';
    $tableDescription->addAttributeToSelect('*');
    $tableDescription->getSelect()->join(
        ['s' => 'sales_order_address'],
        $joinConditions,
        []
    )->columns("s.country_id");
    foreach ($tableDescription as $columnInfo) {
        $this->addFilterToMap($columnInfo['COLUMN_NAME'], 'main_table.' . $columnInfo['COLUMN_NAME']);
    }
    return $this;
}

its still showing only sales_order_grid's column, country_id still blank in my admin grid.

Answer 1

<?php

namespace Krish\CustomAdmin\grid;

class Collection extends \Magento\Sales\Model\ResourceModel\Order\Grid\Collection
{
    protected function _initSelect()
    {
        parent::_initSelect();

        $this->getSelect()->joinInner(
            ['secondTable' => $this->getTable('sales_order_address')],
            "main_table.entity_id = secondTable.parent_id AND secondTable.address_type = 'shipping'"
        );
        $this->addFilterToMap('country_id', 'country_id');
        return $this;
    }
}