Magento getFirstItem and getLastItem not working on collection

Question

My code is as below but it won't work with loading first or last item.

    $shipidarr[0] = 100007536;

$shipModel = Mage::getModel('orderstatus/orderstatus')->getCollection();
    $shipModel->addFieldToFilter('shipment_incrementid', array(array('like' => $shipidarr[0].'%')))->getLastItem();

Answer 1

try this

$shipModelCollection = Mage::getModel('orderstatus/orderstatus')->getCollection();
$shipModelCollection->addFieldToFilter('shipment_incrementid', array(array('like' => $shipidarr[0].'%')));

if($shipModelCollection->getSize()){
$lastItem = $shipModelCollection->getLastItem();

}

Answer 2

The reason you are not getting result with getFirstItem or getLastItem on your collection is because they are function which return values. If a function returns data, then you must use a variable to store the returned value.
check Varien_Data_Collection::getFirstItem() in lib\Varien\Data\Collection.php

/**
 * Retrieve collection last item
 *
 * @return Varien_Object
 */
public function getLastItem()
{
    $this->load();

    if (count($this->_items)) {
        return end($this->_items);
    }

    return new $this->_itemObjectClass();
}

You can see in its details @return Varien_Object it returns Varian_Object.
As this function returns data, you have to use a variable to get returned data or it will give you full collection data with filter.
Thats why

$shipModel->addFieldToFilter('shipment_incrementid', array(array('like' => $shipidarr[0].'%')))->getLastItem();

will give you full collection with filtered data and

$lastItem = $shipModel->addFieldToFilter('shipment_incrementid', array(array('like' => $shipidarr[0].'%')))->getLastItem();

will give you last item by code end($this->_items);

Answer 3

Try this:

$shipModelCollection = Mage::getModel('orderstatus/orderstatus')->create()->addFieldToFilter('shipment_incrementid', array(array('like' => $shipidarr[0].'%')))->getLastItem();