How to copy a product's attributes value to another attribute in Magento?

问题

Is there a way in Magento where I can assign Attribute X's value to Attribute Y programmatically ?

So far I have tried this. I created the Y attribute with following settings:

$setup->addAttribute('catalog_product','myAttribute',array(
                   'group'=>'General',
                   'input'=>'label',
                   'type'=>'varchar',
                   'label'=>'Value of Attribute X',
                   'visible'=>1,
                   'backend'=>'beta/entity_attribute_backend_myattribute',
                   'global'=>Mage_Catalog_Model_Resource_Eav_Attribute::SCOPE_STORE
               ));

In my backend model, I have done this:

class Namespace_Module_Model_Entity_Attribute_Backend_Myattribute extends Mage_Eav_Model_Entity_Attribute_Backend_Abstract
{
    public function beforeSave($object){
        $attrCode = $this->getAttribute()->getAttributeCode();
        $object->setData($attrCode,'HAHAHA');
        parent::beforeSave($object);
        return $this;
    }
}

I am able to see "HAHAHA" as the attribute value in the Product Edit page. I want to change this to value of another attribute. How do I do it ? How do I access another attribute's value of the same product from this class ?

PS: What I am actually trying to achieve is this. The attribute X is of type multiselect with 100s of options. So the attribute Y must keep track of the options selected of X, and Y shows the value in product page in readonly format.

回答1:

I have solved this finally. I went by a different approach, I used Observer. This is what I did:

I created an Observer with following code:

class Namespace_Module_Model_Observer
{

private $_processFlag; //to prevent infinite loop of event-catch situation
public function  copyAttribute($observer){

    if(!$this->_processFlag):

    $this->_processFlag=true;
    $_store = $observer->getStoreId();
    $_product = $observer->getProduct();
    $_productid = $_product->getId();

    $attrA = $_product->getAttributeText('attributeA'); //get attribute A's value

    $action = Mage::getModel('catalog/resource_product_action');
    $action->updateAttributes(array($_productid), array('attributeB'=>$attrA),$_store); //assign attrA's value to attrB
    $_product->save();
    endif;
}

And my config.xml went like this:

<events>
            <catalog_product_save_after>
                <observers>
                    <namespace_module>
                        <type>singleton</type>
                        <class>Namespace_Module_Model_Observer</class>
                        <method>copyAttribute</method>
                    </namespace_module>
                </observers>
            </catalog_product_save_after>
        </events>

So basically, I am using the event catalog_product_save_after which is fired whenever a product is saved. In my observer, I catch the event, get attributeA's value and assign to attributeB, and finally save my product.

That's it! I don't know if this is the best method, but it does work!

来源：https://stackoverflow.com/questions/22102367/how-to-copy-a-products-attributes-value-to-another-attribute-in-magento

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