Interacting with the database

Active records and magic getters

The OXID eShop architecture is based on an MVC design pattern. To implement models, the Active Record pattern is used. In general, each model class is linked to a database table. For example, the Article model is linked to the oxarticles table, Order to the oxorders table etc. All models are stored in the Application/Models directory. Let’s take one of them, for example the Article model, and try to fetch the product (with the ID demoId) data from database:

$product = oxNew(\OxidEsales\Eshop\Application\Model\Article::class); // creating model's object
$product->load( 'demoId' ); // loading data
//getting some information
echo $product->oxarticles__oxtitle->value;
echo $product->oxarticles__oxshortdesc->value;

Magic getters are used to get models attributes; they are constructed in this approach:

$model->tablename__columnname->value;
'tablename' is the name of the database table where the model data is stored
'columnname' is the name of the column of this table containing the data you want to fetch

To set data to a model and store it, database magic setters (with the same approach as magic getters) are used:

$product = oxNew(\OxidEsales\Eshop\Application\Model\Article::class);
$product->oxarticles__oxtitle = new \OxidEsales\Eshop\Core\Field ( 'productTitle' );
$product->oxarticles__oxshortdesc = new \OxidEsales\Eshop\Core\Field( 'shortdescription' );
$product->save();

In this example the new record will be inserted into the table. To update information, we load the model, set the new data and call the save() method:

$product = oxNew(\OxidEsales\Eshop\Application\Model\Article::class);
$product->load( 'demoId' );
$product->oxarticles__oxtitle = new \OxidEsales\Eshop\Core\Field ( 'productTitle' );
$product->oxarticles__oxshortdesc = new \OxidEsales\Eshop\Core\Field( 'shortdescription' );
$product->save();

There are other ways to do the same - without loading the data - just by simply setting the ID with the setId()-method:

$product = oxNew(\OxidEsales\Eshop\Application\Model\Article::class);
$product->setId( 'demoId' );
$product->oxarticles__oxtitle = new \OxidEsales\Eshop\Core\Field( 'productTitle' );
$product->oxarticles__oxshortdesc = new \OxidEsales\Eshop\Core\Field( 'shortdescription' );
$product->save();

In this example there is a check to determine if this ID exists and if so, the record in the database will be updated with the new record.

Making a query

In order to execute a query, an instance of QueryBuilderFactoryInterface is required to create the Query Builder.

Since it is a service, you can use the same methods as with every other service. Simply inject it into your class:

public function __constructor(QueryBuilderFactoryInterface $queryBuilderFactory)
{
    $this->queryBuilderFactory = $queryBuilderFactory;
}

If you want to access it outside of the services where injecting is not possible, make use of the ContainerFactory (more information):

$container = ContainerFactory::getInstance()->getContainer();
$queryBuilderFactory = $container->get(QueryBuilderFactoryInterface::class);

At this point the database connection is ready and the create method must be called to create a queryBuilder.

$queryBuilder = $queryBuilderFactory->create();

Now all types of SQL queries can be generated, based on the Doctrine DBAL Documentation.

Sample:
$queryBuilder
      ->select('*')
      ->from('oxtplblocks')
      ->where('oxshopid = :shopId')
      ->andWhere('oxblockname = :name')
      ->setParameters([
          'shopId'    => $shopId,
          'name'      => $name,
      ]);

$blocksData = $queryBuilder->execute();
$blocksData = $blocksData->fetchAll();

Note

The application’s data access layer should always be accessed through the DBAL. The use of direct SQL queries is considered a bad practice and should be avoided.

Transactions

If one transaction fails, the whole chain of nested transactions is rolled back completely. In some cases it might not be evident that your transaction is already running within an other transaction.

An example how to catch exceptions inside a database transaction:

// Start transaction outside try/catch block
$database->startTransaction();
try {
    $database->commitTransaction();
} catch (\Exception $exception) {
    $database->rollbackTransaction();
    if (!$exception instanceof DatabaseException) {
        throw $exception;
    }
}

MySQL master slave

Doctrine DBAL handles the master slave replication for the OXID eShop on each request. OXID eShop 6 follows these rules:

  • once the request is routed to the master, it stays on the master.
  • writes and transactions go to master.

Care must be taken when using the OXID eShop database API as this can cause the execution of more requests than necessary against the MySQL master server and underutilize the MySQL slave server.

Different API methods for read and write

There is a difference between the methods DatabaseInterface::select() and DatabaseInterface::execute() The method DatabaseInterface::select() can only be used for read methods (SELECT, SHOW) that return a result set. The method DatabaseInterface::execute() must be used for write methods (INSERT, UPDATE, DELETE) in OXID eShop 6.