How to remove all items in a magento product collection?

Question

Seems doesn't works:

<?php
    $collection = Mage::getModel('catalog/product')->getCollection();
    foreach($collection->getItems() as $key => $_product){
        //product
        $collection->removeItemByKey($key);
    }

?>

$collection is still populated

Answer 1

There's also a possibility to remove all the items without "fake loading" (in opposite to Shay Acrich's answer):

class MyCollection extends SomeCollection {

    // ...

    public function setEmpty()
    {
        $this->clear();
        $this->_totalRecords = 0;
        $this->_setIsLoaded(true);
        return $this;
    }

    // ...

}

Setting _totalRecords to 0 is required in order not to allow getSize() method to reload the collection.

Nevertheless, one needs to extend / modify a collection's code, because both the field _totalRecords and the method _setIsLoaded() are protected.

There should be noted, that if a particular collection ignores flags like _totalRecords and _isCollectionLoaded the above solution may not work as expected.

Answer 2

There's clear() method in Varien_Data_Collection class which clears the collection.

I'm not sure if the method exists in the time the question was asked, but it exists in Magento 1.7