Add a product to order with observer event before save (sales_order_save_before) magento?

Question

How can i add a default product to order with observer event before save the order? I want to do these while i am creating an order for costumer from admin panel. Thank you!

config.xml

<events>
    <sales_order_save_before>
        <observers>
            <library>
                <type>model</type>
                <class>library/observer</class>
                <method>AddProductSaveBefore</method>
            </library>
        </observers>
    </sales_order_save_before>
 </events>

observer.php

 <?php 
 class MyPackage_Library_Model_Observer 
 {
     public function AddProductSaveBefore($observer) 
     {
         $order = $observer->getEvent()->getOrder();
         $product = Mage::getModel('catalog/product')->load("3");
     }
 }
 ?>

Answer 1

Event above is close, but it's sales_order_before_save

Adding a custom entity value in Order table

Answer 2

in config.xml

<events>
    <sales_order_save_after>
        <observers>
            <specialitem>
                <type>singleton</type>
                <class>specialitem/observer</class>
                <method>attachSpecialItem</method>
            </specialitem>
        </observers>
    </sales_order_save_after>
</events>

in Observer.php

public function attachSpecialItem(Varien_Event_Observer $obs) {

    $order = $obs->getEvent()->getOrder();
    $sku = 'SKU OF PRODUCT TO ADD DYNAMICALLY';
    $product = Mage::getModel('catalog/product')->loadByAttribute('sku', $sku);
    $qty = 1;

    $rowTotal = $product->getPrice();
    $order_item = Mage::getModel('sales/order_item')
            ->setStoreId($order->getStore()->getStoreId())
            ->setQuoteItemId(NULL)
            ->setQuoteParentItemId(NULL)
            ->setProductId($product->getId())
            ->setProductType($product->getTypeId())
            ->setQtyBackordered(NULL)
            ->setTotalQtyOrdered($qty)
            ->setQtyOrdered($qty)
            ->setName($product->getName())
            ->setSku($product->getSku())
            ->setPrice($product->getPrice())
            ->setBasePrice($product->getPrice())
            ->setOriginalPrice($product->getPrice())
            ->setRowTotal($rowTotal)
            ->setBaseRowTotal($rowTotal)
            ->setOrder($order);
    $order_item->save();
}

Answer 3

We are on a sales_order_save_before event. So don't make an $order_item->save(), otherwise it's break the magento process, because magento wanna make some save after your code. Just take your $order and use the model method addItem($item)

public function attachSpecialItem(Varien_Event_Observer $obs) {

    /** @var Mage_Sales_Model_Order $order */
    $order = $obs->getEvent()->getOrder();
    $sku = 'SKU OF PRODUCT TO ADD DYNAMICALLY';
    $product = Mage::getModel('catalog/product')->loadByAttribute('sku', $sku);
    $qty = 1;

    $rowTotal = $product->getPrice();
    $orderItem = Mage::getModel('sales/order_item')
            ->setStoreId($order->getStore()->getStoreId())
            ->setQuoteItemId(NULL)
            ->setQuoteParentItemId(NULL)
            ->setProductId($product->getId())
            ->setProductType($product->getTypeId())
            ->setQtyBackordered(NULL)
            ->setTotalQtyOrdered($qty)
            ->setQtyOrdered($qty)
            ->setName($product->getName())
            ->setSku($product->getSku())
            ->setPrice($product->getPrice())
            ->setBasePrice($product->getPrice())
            ->setOriginalPrice($product->getPrice())
            ->setRowTotal($rowTotal)
            ->setBaseRowTotal($rowTotal)
            ->setOrder($order);

            $order->addItem($orderItem);

            return $this;

}