Magento: Mage::getResourceModel, Mage::getModel 和 Mage::getSingleton() 的差別 when

Perfect differece with example for getsingleton and getmodel.

Mage::getSingleton()

Mage::getSingleton() will first check if the same class instance exists or not in the memory. If the instance exists then it will return the same object from the memory. So Mage::getSingleton() is faster than Mage::getModel().

Example

$product1 = Mage::getSingleton('catalog/product');
$product2 = Mage::getSingleton('catalog/product');
           

$product1 and $product2 both will share same memory of OS and return only one instance each time.

Mage::getModel()

Mage::getModel() will create a new instance of an object each time even such object exists in configuration.

Example

$product1 = Mage::getModel('catalog/product');
$product2 = Mage::getModel('catalog/product');
           

$product1 and $product2 both have different instant of same object and also occupy different memory

Mage::getResourceModel()

As far as I know, all collections in Magento are resource models. They are instantiated by

Mage::getResourceModel()
           

or

Mage::getModel()->getCollection()
           

（說白了就是：

Mage::getResourceModel('module/model_collection')

相當于

Mage::getModel('module/model')->getCollection()）

It doesn't really matter which function you use; the latter one simply calls the first one. The Magento team simply chose to make collections part of the resource, probably because collections need to query the database a lot. Usually, you will not have to call

Mage::getResourceModel()

for anything else than collections.

參考：http://stackoverflow.com/a/21154019/602382

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轉自：Magento: Mage::getResourceModel, Mage::getModel 和 Mage::getSingleton() 的差別 when to use Mage::getResourceModel, Mage::getModel and Mage::getSingleton()