Unable to limit product collection size in Magento 1.9.2.3 with custom module

Question

I am using a custom module developed by third party, and i have probem with limiting product collections on my home page by :

$collection->setPageSize(10); 

But the limit will work fine if switch the pager from

20 products per page to show all

The code is :

$collection = Mage::getResourceModel('catalog/product_collection')->addCategoryFilter($category);
    $collection->setVisibility(Mage::getSingleton('catalog/product_visibility')->getVisibleInCatalogIds());
    $collection->getSelect()->order(new Zend_Db_Expr('RAND()'));
    $collection = $this->_addProductAttributesAndPrices($collection)->addStoreFilter()
                        ->addAttributeToFilter('is_deal', 1)
                        ->addAttributeToFilter('deal_approved', 1)
                        ->addAttributeToFilter('deal_type',array(
                                array('attribute'=>'deal_type','neq'=>  AdolMedia_DailyDeals_Model_Product_Attribute_Source_Dealtype::FEATURED_DEAL )
                        ))
                        ->addFieldToFilter('deal_cities',array(
                                array('attribute'=>'deal_cities','finset'=> $current_city),
                                array('attribute'=>'deal_cities', 'eq'=> 0),
                                array('attribute'=>'deal_cities', 'eq'=>  new Zend_Db_Expr('null'))
                        ),'left')
                        ->addAttributeToFilter('deal_from_date', array('or'=> array(
                            0 => array('date' => true, 'to' => $dealTime),
                            1 => array('is' => new Zend_Db_Expr('null')))
                        ), 'left')
                        ->addAttributeToFilter('deal_to_date', array('or'=> array(
                            0 => array('date' => true, 'from' => $dealTime),
                            1 => array('is' => new Zend_Db_Expr('null')))
                        ), 'left')
                        ->addAttributeToSort('deal_from_date', 'desc');
    $collection->setPageSize(10); // not working  
    $this->setProductCollection($collection);

Answer 1

There are several ways to do this:

$collection = Mage::getModel('...')
            ->getCollection()
            ->setPageSize(20)
            ->setCurPage(1);

Will get first 20 records.

Here is the alternative and maybe more readable way:

$collection = Mage::getModel('...')->getCollection();
$collection->getSelect()->limit(20);

This will call Zend Db limit. You can set offset as second parameter.

Answer 2

I had this problem sometimes when I did not realize that the collection had already been loaded when I tried to set the page size.

So, you could try to change the order of your function calls: use $collection->getSelect()->limit(20); or $collection->setPageSize(10); directly after $collection->getSelect()->order(new Zend_Db_Expr('RAND()'));.

Another possibility is to call the clear() method on the collection; this will reset the $_isLoaded flag, and will force a new database request - be careful with performance issues here, though. So the code here would be:

$collection->clear(); $collection->setPageSize(10);

Answer 3

From your description, I assume that $this is a product list block that uses the pager toolbar. The toolbar block applies the page size limit to the collection based on default value and session variable or request parameter. It does not apply any limit if "show all" is selected, that's why your value is not overridden in this case.

You can set the limit directly on the toolbar block to bypass the normal calculation.

Replace

$collection->setPageSize(10);

with

$this->getToolbarBlock()->setData('_current_limit', 10);