Question

Simply put, I’m getting this error in the Product Admin of Magento after adding a new edit tab.

Fatal error: Call to a member function createBlock() on a non-object in
/var/www/app/code/local/RedoxStudios/ErpTab/Block/Adminhtml/Catalog/Product/Tab.php
on line 11

I’m having this in my code:

<?php
class RedoxStudios_ErpTab_Block_Adminhtml_Catalog_Product_Tab
extends Mage_Adminhtml_Block_Template
implements Mage_Adminhtml_Block_Widget_Tab_Interface {

    /*
     * Set the template for the block
     */
    public function __construct() {
        parent::__construct();
        $this->getLayout()->createBlock('Purchase/Product_Widget_StockDetails_Summary');
        $this->setProduct($this->getProduct());
        $this->setTemplate('Purchase/Product/StockDetails/Summary.phtml');
    }

    /**
    * Return current product instance
    *
    * @return Mage_Catalog_Model_Product
    */

    public function getProduct()
    {
        return Mage::registry('product');
    }
}

Previously I was able to just call the createBlock function. I’m I overlooking something that makes it that I cannot call this function?

---

Summary.phtml:

<div class="stock-details-summary">

<table border="0">
    <tr>
        <td class="a-right"><?php echo $this->__('Waiting for delivery'); ?> : </td>
        <td class="a-right"><?php echo ($this->getWaitingForDeliveryQty() ? $this->getWaitingForDeliveryQty() : 0); ?></td>
    </tr>
    <tr>
        <td class="a-right">
            <?php echo $this->__('Manual supply need'); ?> : 
            <?php if ($this->getManualSupplyNeedQty() > 0): ?>
                <i><?php echo $this->getProduct()->getmanual_supply_need_comments(); ?></i>
            <?php endif; ?>
        </td>
        <td class="a-right">
            <?php echo $this->getManualSupplyNeedQty(); ?>
        </td>
    </tr>
    <tr>
        <td class="a-right"><?php echo $this->__('Min qty to purchase'); ?> : </td>
        <td class="a-right"><font color="red"><?php echo $this->getTotalNeededQtyForValidOrdersMinusWaitingForDelivery(); ?></font></td>
    </tr>
    <tr>
        <td class="a-right"><?php echo $this->__('Max qty to purchase'); ?> : </td>
        <td class="a-right" width="60"><font color="red"><?php echo $this->getTotalNeededQtyMinusWaitingForDelivery(); ?></font></td>
    </tr>
    <tr>
        <td class="a-right"><?php echo $this->__('Status'); ?> : </td>
        <td class="a-right"><?php echo $this->getGeneralStatus(); ?></td>
    </tr>
</table>

</div>

Answer 1

You are not correctly getting the layout object (Mage_Core_Model_Layout). In action controllers and blocks it’s $this->getLayout()->createBlock(), everywhere else it’s Mage::app()->getLayout()->createBlock()

EDIT: Sergy also pointed out that the layout object is not loaded, and this caused me to realize that you are using the php __construct(), rather than the typical Magento _construct(). Block instances do not have the layout object set on them until after they are instantiated (and their constructor has been called) in Mage_Core_Model_Layout::createBlock() – notice in that method how the block instance gets the layout set on it via its setLayout() method. This is the purpose behind the block method _prepareLayout() – it’s a constructor-like method which is fired after the block instance is created.

Corrections to your code below:

<?php
class RedoxStudios_ErpTab_Block_Adminhtml_Catalog_Product_Tab
extends Mage_Adminhtml_Block_Template
implements Mage_Adminhtml_Block_Widget_Tab_Interface {

    /*
     * Set the template for the block
     */
    protected function _construct()
    {
        $this->setTemplate('Purchase/Product/StockDetails/Summary.phtml');
    }

    public function _prepareLayout()
    {
        $this->getLayout()->createBlock('Purchase/Product_Widget_StockDetails_Summary');
        $this->setProduct($this->getProduct());
    }

    // ...
}