Call to a member function getProductId() on a non-object?

Question

I have created custom module, In that I have just override the Mage_Catalog_Block_Product class to get the getPrice(). But it's returning an error Call to a member function getProductId() on a non-object?

my php code is:

//controller

<?php
class Course_Mca_IndexController extends Mage_Core_Controller_Front_Action
{
    public function indexAction()
    {
        $this->loadLayout();
        $this->renderLayout();
    }
}

//block file

<?php    

class Course_Mca_Block_Products extends Mage_Catalog_Block_Product
{
    public function getPrice()
    {
          return parent::getPrice();
    }
}

//web.phtml file

<?php echo $this->getPrice() ?>

//layout.xml file

<?xml version="1.0"?>
<layout version="0.1.0">
    <mca_index_index>
        <reference name="content">
            <block type="mca/products" name="mca_mca" template="mca/web.phtml"></block>
        </reference>
    </mca_index_index>
</layout>

//Course_mca.xml

<?xml version="1.0"?>
<config>
    <modules>
        <Course_Mca>
            <active>true</active>
            <codePool>local</codePool>
            <depends>
                <Mage_Catalog/>
            </depends>
        </Course_Mca>
    </modules>
</config>

//config.xml

<blocks>
<!-- it's not working -->
        <!-- <catalog>
              <rewrite>
                  <product>Course_Mca_Block_Products</product>
              </rewrite>
          </catalog>-->
<!-- it's working -->
            <mca>
               <class>Course_Mca_Block</class>
           </mca>
    </blocks>

Can anyone tell me where I went wrong?

Thanks in advance.

Answer 1

take a look at the original getPrice method.
It looks like this:

public function getPrice()
{
    return $this->getProduct()->getPrice();
}

Digging deeper you end up in Mage_Catalog_Block_Product::getProduct() that looks like this:

public function getProduct()
{
    if (!$this->getData('product') instanceof Mage_Catalog_Model_Product) {
        if ($this->getData('product')->getProductId()) {
            $productId = $this->getData('product')->getProductId();
        }
        if ($productId) {
            $product = Mage::getModel('catalog/product')->load($productId);
            if ($product) {
                $this->setProduct($product);
            }
        }
    }
    return $this->getData('product');
}

In your case $this->getData('product') return null, and since null is not an instance of Mage_Catalog_Model_Product you enter the first if statement and it crashes on this line: if ($this->getData('product')->getProductId()) { because you cannot call null->getProductId().

Any instance of Mage_Catalog_Block_Product makes sense if you attach a product to it. Considering your layout file, I can conclude that you are trying to use your block without any product.

Here is how your Mca_IndexController::indexAction() should look:

$this->loadLayout();
$block = $this->getLayout()->getBlock('mca_mca');
if ($block){
    $productId = 15;//for example
    $product = Mage::getModel('catalog/product')->setStoreId(Mage::app()->getStore()->getId())->load($productId);
    $block->setProduct($product);
}
$this->renderLayout();