How to restrict the number of products in a collection and modify search filters accordingly?

Question

UPDATE: this is partially answered(for someone who comes here lately).The answers does not updated the search filters.

I want to limit my product collection in any category/subcategory landing page with the help of a url parameter say itemlimit=10

I tried to do this in my phtml with setPageSize(3) but this is setting the number of product in a page so the filters wont get modified accordingly.

Then i tried to do it with

$collection->getSelect()->limit(10);

and getting an error like this

Unrecognized method 'setCurPage()'

Am I doing the wrong thing? Should I override the catalog resource model collection for this?

EDIT:

This is my custom block class

class Ziva_Customcatalog_Block_Product_List extends Mage_Catalog_Block_Product_List {
    public function __construct() {
        parent::__construct();
    }

    protected function _getProductCollection() {
        $collection = Mage::getModel('catalog/product')->getCollection();
        return $collection->getSelect()->limit(10); // This will first 10 results    
    }
}

EDIT as asked: the entire trace

#0 C:\wamp\www\magento2\app\code\core\Mage\Catalog\Block\Product\List\Toolbar.php(225): Zend_Db_Select->__call('setCurPage', Array)
#1 C:\wamp\www\magento2\app\code\core\Mage\Catalog\Block\Product\List\Toolbar.php(225): Varien_Db_Select->setCurPage(1)
#2 C:\wamp\www\magento2\app\code\core\Mage\Catalog\Block\Product\List.php(158): Mage_Catalog_Block_Product_List_Toolbar->setCollection(Object(Varien_Db_Select))
#3 C:\wamp\www\magento2\app\code\core\Mage\Core\Block\Abstract.php(862): Mage_Catalog_Block_Product_List->_beforeToHtml()
#4 C:\wamp\www\magento2\app\code\core\Mage\Core\Block\Abstract.php(582): Mage_Core_Block_Abstract->toHtml()

.................................................. #27 C:\wamp\www\magento2\app\code\core\Mage\Core\Model\App.php(354): Mage_Core_Controller_Varien_Front->dispatch() #28 C:\wamp\www\magento2\app\Mage.php(683): Mage_Core_Model_App->run(Array) #29 C:\wamp\www\magento2\index.php(87): Mage::run('', 'store') #30 {main}

Answer 1

Try this : Updated answer

config.xml

<config>
 . . . . . 
<global>  
        <blocks>
            <home>
                <class>Test_Home_Block</class>
            </home>
            <catalog>
                <rewrite>
                    <product_list>Test_Home_Block_Product_List</product_list>
                </rewrite>
            </catalog>
        </blocks> 
 . . . . . .
</global>
 . . . . . 
</config>

~\app\code\local\Test\Home\Block\Product\List.php

<?php
class Test_Home_Block_Product_List extends Mage_Catalog_Block_Product_List
{
     protected function _getProductCollection()
    {
        $collection = parent::_getProductCollection(); 
        $noOfItems = 5; // The number of items which you want to show.
        $count = 0;
        $myProductCollection = new Varien_Data_Collection();
        foreach($collection as $product)
        {
            if($count < $noOfItems) {
                $myProductCollection->addItem($product);
                $count++;
            } else {
                break;
            }
        }

        return $myProductCollection;
    }
}

Answer 2

If you only want to filter category_view you could listen to the event which is triggered just before the collection gets loaded. In your config.xmls global section:

<events>
    <catalog_block_product_list_collection>
        <observers>
            <ziva_customcatalog_catalog_block_product_list_collection>
                <class>ziva_customcatalog/observer</class>
                <method>catalogBlockProductListCollection</method>
            </ziva_customcatalog_catalog_block_product_list_collection>
        </observers>
    </catalog_block_product_list_collection>
</events>

In your Observer model you can alter the collection:

/**
 * @param Varien_Event_Observer $observer
 * @return Ziva_Customcatalog_Model_Observer
 */
public function catalogBlockProductListCollection(Varien_Event_Observer $observer)
{
    $collection = $observer->getCollection();
    if($collection) {
        //todo: get params from request
        $collection->getSelect()->limit(10);
    }
    return $this;
}

The event gets dispatched in app/code/core/Mage/Catalog/Block/Product/List.php:161.