Filter in grid not working with Varien_Data_Collection

Question

I have created custom collection with Varien_Data_Collection in admin grid like below :

protected function _prepareCollection() {
    $collection = Mage::getModel("catalog/product")->getCollection()
                     ->addAttributeToFilter('entity_id', array('in' => $productIds))
                    ->addAttributeToSelect($attributes)
                    ->addAttributeToSelect("sku")
                    ->addWebsiteFilter($websiteID)
                    ->addAttributeToFilter("type_id", "simple");
    $dataArray = array();

    foreach($collection as $item)
    {
        $productID = $item->getData('product_id');
        $req_qty   = Mage::helper("purchasemanagement")->getRequiredQty($productID);
        $dataArray[$item->getId()] = $item->getData();
        $dataArray[$item->getId()]['req_qty'] = $req_qty;
    }
    usort($dataArray,array($this, '_sortItems'));

    $new_collection = new Varien_Data_Collection();
        foreach($dataArray as $row){
            $rowObj = new Varien_Object();
            $rowObj->setData($row);
            $new_collection->addItem($rowObj);
        }

        $this->setCollection($new_collection);
        return parent::_prepareCollection();
}

But now i am not able to filter in this custom collection. I get the below error :

Call to undefined method Varien_Data_Collection::addFieldToFilter() in app\code\core\Mage\Adminhtml\Block\Widget\Grid.php on line 472

I tried to follow these two links :

1) Filtering error when using custom Varien object collection in admin grid

2) Magento 1 : Filtering / Paging / Sorting with Varien_Data_Collection

but none of them worked. Can anyone tell me how to implement the solution ?

Thanks in advance.

Answer 1

You can try with below method, YOu can remove $rowObj = new Varien_Object(); and directly set inside collection,

    $new_collection = new Varien_Data_Collection();
    foreach($dataArray as $row){
        if (isset($row)) {
            $new_collection->addItem($row);
        }
    }
    $this->setCollection($new_collection);
    return parent::_prepareCollection();