Filter Products with layered navigation using AND condition

Question

i need to change the layered navigation feature a little bit, currently it filter product attributes on "OR" condition like Product 1 Red, blue, pink

Product 2 Red

Product 3 Blue

On selecting filter options “red” and “blue” in the layered nav, the product collection includes Product 1, Product 2 and Product 3. I just want it to return Product 1. I tried to it by modifying

->where($alias.'.value IN (?)', $ids);

to

foreach ($ids as $key => $value) {
     $collection->getSelect()->where($alias.'.value = ?', $value);
    }

but with this when i select two option, it doesn't return a value.

Answer 1

In order to manage to get my task done. I overridden the applyMultipleValuesFilter($ids) to something like this

protected function applyMultipleValuesFilter($ids)
{
    $attribute  = $this->getAttributeModel();
    $table = Mage::getSingleton('core/resource')->getTableName('catalogindex/eav'); 
    $alias = 'attr_index_'.$attribute->getId();
    $hvngquery = ' ';
    $i= count($ids)-1;
    foreach ($ids as $key => $value) 
    {
        $hvngquery .= '(SUM(`'.$alias.'`.`value`= "'.$value.'") > 0)';
        if ($i>0) 
        {
          $hvngquery .= ' AND ';
         } 
         $i = $i-1;
    }

    $collection = $this->getLayer()->getProductCollection();

    $collection->getSelect()->join(
        array($alias => $table),
        $alias.'.entity_id=e.entity_id',
        array()
    )         
    ->where($alias.'.store_id = ?', Mage::app()->getStore()->getId())
    ->where($alias.'.attribute_id = '. $attribute->getId()) 
     ->group('e.entity_id')
     ->having($hvngquery);

    return $this;
}   

This then generates an unknown field error in query (if you run the query directly in phpmyadmin it works but error occurs only in magento) for this i had to modify _getBaseCollectionSql() to add having clause to collection