conversion of magento 1 into magento 2 - magento2

Question

I was using fetch_assoc() method in magento 1 .
I want to convert it into Magento 2 . there is no fetch_assoc() method in magento 2.
if(is_object($result))
{
while ($resultsArray =$result->fetch_assoc())
{
if(empty($data))
{
$data[] = array_keys($resultsArray);
}
$data[] = $resultsArray;
} var_dump($data);
}

Answer 1

I'm not sure my proposed solution is useful for you or not but the best approach to fetch data in Magento 2 is based on Models and Collections.
Step 1: Firstly, you have to create a Model file in your module
<?php
namespace <Vendor_Name>\<Module_Name>\Model;
use Magento\Framework\Model\AbstractModel;
class Data extends AbstractModel
{
protected function _construct()
{
$this->_init('<Vendor_Name>\<Module_Name>\Model\ResourceModel\Data');
}
}
Step 2: Create ResourceModel file in your custom module
<?php
namespace <Vendor_Name>\<Module_Name>\Model\ResourceModel;
use \Magento\Framework\Model\ResourceModel\Db\AbstractDb;
class Data extends AbstractDb
{
protected function _construct()
{
// Second parameter is a primary key of the table
$this->_init('Table_Name', 'id');
}
}
Step 3: Create Collection file to initialize Model and ResourceModel files.
namespace <Vendor_Name>\<Module_Name>\Model\ResourceModel\Data;
use Magento\Framework\Model\ResourceModel\Db\Collection\AbstractCollection;
class Collection extends AbstractCollection
{
protected function _construct()
{
$this->_init(
'<Vendor_Name>\<Module_Name>\Model\Data',
'<Vendor_Name>\<Module_Name>\Model\ResourceModel\Data'
);
}
}
Step 4: Last thing that you need to do is create a Block file in the same module and utilize collection, something like this:
namespace <Vendor_Name>\<Module_Name>\Block;
use Magento\Framework\View\Element\Template\Context;
use Magento\Framework\View\Element\Template;
use <Vendor_Name>\<Module_Name>\Model\Data as DataCollection;
class Custom_Module extends Template
{
protected $dataCollection;
public function __construct(Context $context, DataCollection $dataCollection)
{
$this->_dataCollection = $dataCollection;
parent::__construct($context);
}
public function getDataCollecton()
{
$collection = $this->_dataCollection->getCollection();
return $collection;
}
}
Another Solution
You can also use fetchAll instead of fetch_assoc() in Magento 2, if you don't want to implement models and collections based solution, something like this:
// Select Data from table
$sql = "Select * FROM " . $tableName;
$result = $connection->fetchAll($sql);
and for reference, you can also have a look into Magento2 – Write Custom Mysql Query (Without Using Model)

Answer 2

I think we can use something like below :
$adapter = $this->resourceConnection->getConnection($resource);
$stmt = $adapter->query($sql);
// Use FETCH_NUM so we are not dependent on the CASE attribute of the PDO connection
$results = $stmt->fetchAll(\Zend_Db::FETCH_ASSOC);
Or if we have $connection instanceof \Magento\Framework\DB\Adapter\AdapterInterface
$connection->fetchAll($sql, $binds, \PDO::FETCH_ASSOC);
By using those, i think you're gonna get the same result to magento 1 fetch_assoc

Answer 3

Alternative of the fetch_assoc() in magento 2 is fetchAssoc($SQL_QUERY)
Below is the example.
For get order where status is pending data using fetchAssoc(SQL_QUERY)
<?php
namespace Path\To\Class;
use Magento\Framework\App\ResourceConnection;
class fetchAssoc {
const ORDER_TABLE = 'sales_order';
/**
* #var ResourceConnection
*/
private $resourceConnection;
public function __construct(
ResourceConnection $resourceConnection
) {
$this->resourceConnection = $resourceConnection;
}
/**
* fetchAssoc Sql Query
*
* #return string[]
*/
public function fetchAssocQuery()
{
$connection = $this->resourceConnection->getConnection();
$tableName = $connection->getTableName(self::ORDER_TABLE);
$query = $connection->select()
->from($tableName,['entity_id','status','grand_total'])
->where('status = ?', 'pending');
$fetchData = $connection->fetchAssoc($query);
return $fetchData;
}
}

Answer 4

In magento 2 you can use same but for that you need to create database connection.
I suggest you to use resource or collection models to get the result and if you want to get the first row in object format then you should use
getFirstItem();

Answer 5

I think Magento 2 has support for this in class \Magento\Framework\DB\Adapter\AdapterInterface. You can create an instance for AdapterInterface by dependency injection or directly by object manager.
$objectManager = \Magento\Framework\App\ObjectManager::getInstance();
/** #var \Magento\Framework\App\ResourceConnection $resourceConnection */
$resourceConnection = $objectManager->get(\Magento\Framework\App\ResourceConnection::class);
/** #var \Magento\Framework\DB\Adapter\AdapterInterface $connection */
$connection = $resourceConnection->getConnection(\Magento\Framework\App\ResourceConnection::DEFAULT_CONNECTION);
$sql = "YOUR SELECT QUERY HERE";
$data = $connection->fetchAssoc($sql);