how does the Image Gallery form get populated in Magento Admin

Question

I can see that Mage_Adminhtml_Block_Catalog_Product_Helper_Form_Gallery_Content::getImagesJson() and app\design\adminhtml\default\default\template\catalog\product\helper\gallery.phtml are responsible for putting the image data into the browser via the Product.Gallery prototype class.

However, I can't track down where the image collection gets set on the Mage_Adminhtml_Block_Catalog_Product_Helper_Form_Gallery_Content block. I'm assuming its via a magic setter somewhere in the controller or layout, but I can't track it down.

Mage_Adminhtml_Block_Catalog_Product_Helper_Form_Gallery_Content::getImagesJson() has

$value = $this->getElement()->getValue();
        if(count($value['images'])>0) {
            foreach ($value['images'] as &$image) {

so something is populating the element attribute of that block.

Mage_Adminhtml_Block_Catalog_Product_Helper_Form_Gallery_Content seems to be instantiated by Mage_Adminhtml_Block_Catalog_Product_Helper_Form_Gallery::getContentHtml() but that doesn't set any attributes on the block.

I can see that Mage_Catalog_Model_Product_Attribute_Backend_Media::afterLoad() populates the attribute with an array that matches the structure that the Product.Gallery Javascript is looking for, but I'm still a little mystified as to where the Attribute gets tied to the rendering Block.

I think I need a diagram to keep this tangled web straight in my head!

Thanks,
Jonathan

Answer 1

You say;

... seems to be instantiated by Mage_Adminhtml_Block_Catalog_Product_Helper_Form_Gallery::getContentHtml() but that doesn't set any attributes on the block.

But getContentHtml() looks like this:

/**
 * Prepares content block
 *
 * @return string
 */
public function getContentHtml()
{

    /* @var $content Mage_Adminhtml_Block_Catalog_Product_Helper_Form_Gallery_Content */
    $content = Mage::getSingleton('core/layout')
        ->createBlock('adminhtml/catalog_product_helper_form_gallery_content');

    $content->setId($this->getHtmlId() . '_content')
        ->setElement($this);
    return $content->toHtml();
}

It clearly sets the element for $content to $this, which is the Mage_Adminhtml_Block_Catalog_Product_Helper_Form_Gallery object.