I managed to put up a EcomDev_PHPUnit_Test_Case with this:

public function testGetModelMemoryTrace() {
    $model = Mage::getModel('catalog/product');
    $product = $model->load(10);
    $this->assertEquals($product->getId(), 10);
    $parentProduct = $model->load(4);
    $this->assertEquals($product->getId(), 10); //here getId() is actually 4...

This test fails for me in the last assert. Is this an expected effect ? To clarify, the second load alters first reference to object id 10.

Thank you.

2 Answers 2


$model->load doesnt return a new instance. It returns itself. So $model, $product and $parentProduct is actually the same instance.

  • 1
    exactly, while Mage::getModel('catalog/product') is a factory and returns always a new instance, the ->load() is only a method which returns $this.
    – Flyingmana
    Commented Oct 25, 2014 at 11:21

Problem is here... When you load prroduct at second time the yoy took variable $parentProduct and you are passing variable $product.

$product contain reference of product id 10 and

$parentProduct contain reference of product id 4.

Thant's why you are getting 10 as product id at second time. So either need to change $product->getId() to $parentProduct->getId() or when you are loading product at second time for id 4 then re-assign it to variable $product.

Hope this will help you.

  • I intentionally did that to show collateral effect of model loadings. Please run the test and you will understand.
    – Niloct
    Commented Oct 25, 2014 at 8:42
  • I understand, you are correct that load doesn't return an instance but look variable $product have data of product id 10 and once its initialized, then even if you change the instance data by loading another product then still variable $product have data which was loaded for product id 10 because it have own memory space. So wherever you use that variable it will always return 10.
    – Kumar M
    Commented Oct 26, 2014 at 10:17
  • You missed the point that $model, $product, $parentProduct all point to the same object. So you said that once loading product id 10, that will always remain even with another load ? That is not true, because loading product id 4 after 10 changed these three references. Read the other answer and other comment please.
    – Niloct
    Commented Oct 26, 2014 at 15:45
  • I never said that they aren't pointing same object. They are pointing same object i know but i am talking about the variables($product and $parentProduct) that you are using to assign every time for different product data.
    – Kumar M
    Commented Oct 26, 2014 at 17:08

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