Calling load with attribute name - $product->load('attribute_name');

Question

Looking through one of the projects I've been working on, I keep coming across code that does $product->load('attribute_name'), where product is an instance of Mage_Catalog_Model_Product. Digging down through the code for a product model, I fail to see what this is supposed to do. Is this just a misunderstanding by whoever wrote this custom code, or am I missing something?

As far as I'm concerned this would attempt to load a product with the id of 'attribute_code', which doesn't exist. In this situation it would hit Mage_Eav_Model_Entity_Abstract::load with $product, 'attribute_code', array() as the arguments. This would actually mark the current model as new with isObjectNew(true) since it can't be loaded from the database, but since $attributes is empty it will trigger Mage_Eav_Model_Entity_Abstract::loadAllAttributes, which due to the fact the model was partly loaded and thus contains an entity_id already, fetches all attributes from the database for that entity_id. If this is the case, the string 'attribute_code' is somewhat irrelevant (so long as it isn't the entity_id of another product) and all attributes will be loaded for the entity_id contained in the model.

Is my understanding correct, or am I missing something?

Answer 1

In short, yes what you are suggesting is correct. The select statement built when calling the load in you question would be the following.

SELECT `catalog_product_entity`.* FROM `catalog_product_entity` WHERE (entity_id ='attribute_name')

You can find this out by adding some debug into the load method in Mage_Eav_Model_Entity_Abstract

If you are actually wanting to load a product via an attribute that is not entity_id the the following snippet would do it.

Mage::getModel('catalog/product')->loadByAttribute('sku', 'My Sku Value');

NOTE: with loadByAttribute if the attribute is not unique then the first object found will be returned

SECOND NOTE: this will return either an object or false (thanks Fabian)

Answer 2

In addition to David Manners ...

If you are actually wanting to load a product via an attribute that is not entity_id the the following snippet would do it.

Mage::getModel('catalog/product')->loadByAttribute('sku', 'My Sku Value');

To speed up loading you should take care of loadByAttribute 3rd parameter.

^{https://github.com/OpenMage/magento-lts/blob/1.9.3.x/app/code/core/Mage/Catalog/Model/Abstract.php#L216-L235}

/**
 * Load entity by attribute
 *
 * @param Mage_Eav_Model_Entity_Attribute_Interface|integer|string|array $attribute
 * @param null|string|array $value
 * @param string $additionalAttributes
 * @return bool|Mage_Catalog_Model_Abstract
 */
public function loadByAttribute($attribute, $value, $additionalAttributes = '*')
{
    $collection = $this->getResourceCollection()
        ->addAttributeToSelect($additionalAttributes)
        ->addAttributeToFilter($attribute, $value)
        ->setPage(1,1);

    foreach ($collection as $object) {
        return $object;
    }
    return false;
}

Set $additionalAttributes to null (just default attributes) or array('your', 'attributes', 'here') for your own.

$attributesToSelect = array('name');
Mage::getModel('catalog/product')->loadByAttribute('sku', 'My Sku Value', $attributesToSelect);