Random product collection, getPriceHTML gives wrong values

Question

I am creating a random list of products that refreshes every hour. I've got most of it done but there is one problem: getPriceHTML is returning NULL. This function is used in the normal category product lists and works perfectly there.

This code does give a correct getPriceHTML

$_productCollection = Mage::getModel('catalog/product')->getCollection();

But what I need is to get a random product, no matter what category it is in, so that is not an option.

The following code is the code I use to get random products:

$this->_productCollection = Mage::getResourceModel('catalog/product_collection');
Mage::getModel('catalog/layer')->prepareProductCollection($this->_productCollection);
$this->_productCollection->getSelect()->order('rand()');
$this->_productCollection->addStoreFilter();
$this->_productCollection->setPage(1, 3);

And later on:

foreach($this->_productCollection AS $_product)
{
    echo $this->getPriceHtml($_product, true);
}

For simple products this does give the correct price, but it returns NULL for grouped products. Yes, I am extending to Mage_Catalog_Block_Product.

Please keep in mind that I know that there are other functions to get the price, but I specifically want to know why this isn't working as it should.

Answer 1

Please take a look at the two implementations for getPriceHtml()

Mage_Catalog_Block_Product

public function getPriceHtml($product)
{
    $this->setTemplate('catalog/product/price.phtml');
    $this->setProduct($product);
    return $this->toHtml();
}

vs.

Mage_Catalog_Block_Product_Abstract

public function getPriceHtml($product, $displayMinimalPrice = false, $idSuffix = '')
{
    return $this->_preparePriceRenderer($product->getTypeId())
        ->setProduct($product)
        ->setDisplayMinimalPrice($displayMinimalPrice)
        ->setIdSuffix($idSuffix)
        ->toHtml();
}

extending from the Abstract block should help in getting the correct renderer.