getting all products instead of getting the products from current category in Layer.php

Question

I looked around, and i found something similar but still can solved my problem. So i decided to ask here. sorry if there is a duplicate question already asked.

I want to override the getProductCollection() in Layer.php in magento, but here is my problem.

below is the original code with my own code:

public function getProductCollection()
{

    if (isset($this->_productCollections[$this->getCurrentCategory()->getId()])) {

        $collection = $this->_productCollections[$this->getCurrentCategory()->getId()];

    } else {

        //Original collection code
        //$collection = $this->getCurrentCategory()->getProductCollection();

        /* I want to do the below code*/
        $collection = Mage::getModel('catalog/product')->getCollection();
        $collection->addAttributeToSelect('customYesNoAttribute');
        $collection->addFieldToFilter('customYesNoAttribute', 1);
        /*custom code ends*/


        $this->prepareProductCollection($collection);
        $this->_productCollections[$this->getCurrentCategory()->getId()] = $collection;
    }

    return $collection;  
}

what this code does is that it will get all products for every category, then filter the products for a attribute carry with the Category.

For example:

Category: Cup
Custom Category Attribute: isCup

Product: Coffee Cup
Custom Attribute: isCup->Yes

Product: T-Shirt
Custom Attribute: isCup->No

when i open the "Cup" category, the above code gets the isCup attribute from the category, and filter all products with isCup=Yes, and show on the category.

The main reason why i want to do this is I don't want to manually add products to category because my client has over 5k products. It will be a nightmare to maintain them.

But my problem with the above code is now a blank white page with nothing. Any help will be greatly appreciated.