Magento Overrides – Extending Block Without Access to Private Functions

inheritanceoverrides

I've had to re-write a block of a third party module, I only want to re-write one function in the class but my re-write won't work unless I copy across the private functions from the class I extended.

I read this answer from Alan Storm on stack overflow and read that if your class extends another class, it will not have access to private properties of the base class/object.

That's ok, but what is the best practice for class re-writes if the base class had pricate functions? Should I just add them to my class. What about protected properties?

Here is my class if it helps.

class Creed_CustomMenu_Block_Navigation extends WP_CustomMenu_Block_Navigation
{
        const CUSTOM_BLOCK_TEMPLATE = "wp_custom_menu_%d";

    private $_productsCount = null;

    public function showHomeLink()
    {
        return Mage::getStoreConfig('custom_menu/general/show_home_link');
    }

    public function drawCustomMenuItem($category, $level = 0, $last = false)
    {
        if (!$category->getIsActive()) return '';
        $html = array();
        $id = $category->getId();
        // --- Static Block ---
        $blockId = sprintf(self::CUSTOM_BLOCK_TEMPLATE, $id); // --- static block key
        #Mage::log($blockId);
        $collection = Mage::getModel('cms/block')->getCollection()
            ->addFieldToFilter('identifier', array('like' => $blockId . '%'))
            ->addFieldToFilter('is_active', 1);
        $blockId = $collection->getFirstItem()->getIdentifier();
        #Mage::log($blockId);
        $blockHtml = $this->getLayout()->createBlock('cms/block')->setBlockId($blockId)->toHtml();
        // --- Sub Categories ---
        $activeChildren = $this->_getActiveChildren($category, $level);
        // --- class for active category ---
        $active = ''; if ($this->isCategoryActive($category)) $active = ' act';
        // --- Popup functions for show ---
        // $wideBlock; // = false;  // MC: added new condition for setting extra wide static blocks
        global $wideBlock;
        $wideBlock = false;
        if (strpos($blockId,'wide') !== false) {
            $wideBlock = true;
        }
        $drawPopup = ($blockHtml || count($activeChildren));
        if ($drawPopup) {
            $html[] = '<div id="menu' . $id . '" class="menu' . $active . '" onmouseover="wpShowMenuPopup(this, event, \'popup' . $id . '\');" onmouseout="wpHideMenuPopup(this, event, \'popup' . $id . '\', \'menu' . $id . '\')">';
        } else {
            $html[] = '<div id="menu' . $id . '" class="menu' . $active . '">';
        }
        // --- Top Menu Item ---
        $html[] = '<div class="parentMenu">';
        if ($level == 0 && $drawPopup) {
            $html[] = '<a href="javascript:void(0);" rel="'.$this->getCategoryUrl($category).'">';
        } else {
            $html[] = '<a href="'.$this->getCategoryUrl($category).'">';
        }
        $name = $this->escapeHtml($category->getName());
        if (Mage::getStoreConfig('custom_menu/general/non_breaking_space')) {
            $name = str_replace(' ', '&nbsp;', $name);
        }
        $html[] = '<span>' . $name . '</span>';
        $html[] = '</a>';
        $html[] = '</div>';
        $html[] = '</div>';
        // --- Add Popup block (hidden) ---
        if ($drawPopup) {
            // --- Popup function for hide ---
            $html[] = '<div id="popup' . $id . '" class="wp-custom-menu-popup" onmouseout="wpHideMenuPopup(this, event, \'popup' . $id . '\', \'menu' . $id . '\')" onmouseover="wpPopupOver(this, event, \'popup' . $id . '\', \'menu' . $id . '\')">';
            // --- draw Sub Categories ---
            if ($blockHtml)
            {
                if (count($activeChildren))
                {
                    if ($wideBlock) {
                        $html[] = '<div class="block1 grid12-2 mega-menu-list">';
                        $html[] = '<h3 class="title cat-browse">' . Mage::helper('catalog')->__('Browse by category') . '</h3>' ;
                        $html[] = $this->drawWithoutColumns($activeChildren);
                    } else{
                        $html[] = '<div class="block1 grid12-7">';
                        $html[] = $this->drawColumns($activeChildren);
                    }
                    $html[] = '<div class="clearBoth"></div>';
                    $html[] = '</div>';
                }

                // --- draw Custom User Block ---
                if ($wideBlock) {
                    $html[] = '<div id="' . $blockId . '" class="block2 grid12-10">';
                } else{
                    $html[] = '<div id="' . $blockId . '" class="block2 grid12-5">';
                }
                $html[] = $blockHtml;
                $html[] = '</div>';

            }
            else
                if (count($activeChildren)) {
                    $html[] = '<div class="block1 grid-full">';
                    $html[] = $this->drawColumns($activeChildren);
                    $html[] = '<div class="clearBoth"></div>';
                    $html[] = '</div>';
                }
            $html[] = '</div>';
        }
        $html = implode("\n", $html);
        return $html;
    }

    public function drawWithoutColumns($children)
    {
        $html = '';
        // --- explode by columns ---
        $columns = 0;
        if ($columns < 1) $columns = 1;
        $chunks = $this->_explodeByColumns($children, $columns);
        // --- draw columns ---
        $lastColumnNumber = count($chunks);
        $i = 1;
        foreach ($chunks as $key => $value)
        {
            if (!count($value)) continue;
            $class = '';
            if ($i == 1) $class.= ' first';
            if ($i == $lastColumnNumber) $class.= ' last';
            if ($i % 2) $class.= ' odd'; else $class.= ' even';
            $html.= '<div class="column' . $class . '">';
            $html.= $this->drawMenuItem($value, 1);
            $html.= '</div>';
            $i++;
        }
        return $html;
    }
    protected function _getActiveChildren($parent, $level)
    {
        $activeChildren = array();
        // --- check level ---
        $maxLevel = (int)Mage::getStoreConfig('custom_menu/general/max_level');
        if ($maxLevel > 0)
        {
            if ($level >= ($maxLevel - 1)) return $activeChildren;
        }
        // --- / check level ---
        if (Mage::helper('catalog/category_flat')->isEnabled())
        {
            $children = $parent->getChildrenNodes();
            $childrenCount = count($children);
        }
        else
        {
            $children = $parent->getChildren();
            $childrenCount = $children->count();
        }
        $hasChildren = $children && $childrenCount;
        if ($hasChildren)
        {
            foreach ($children as $child)
            {
                if ($this->_isCategoryDisplayed($child))
                {
                    array_push($activeChildren, $child);
                }
            }
        }
        return $activeChildren;
    }

    private function _isCategoryDisplayed(&$child)
    {
        if (!$child->getIsActive()) return false;
        // === check products count ===
        // --- get collection info ---
        if (!Mage::getStoreConfig('custom_menu/general/display_empty_categories'))
        {
            $data = $this->_getProductsCountData();
            // --- check by id ---
            $id = $child->getId();
            #Mage::log($id); Mage::log($data);
            if (!isset($data[$id]) || !$data[$id]['product_count']) return false;
        }
        // === / check products count ===
        return true;
    }

    private function _getProductsCountData()
    {
        if (is_null($this->_productsCount))
        {
            $collection = Mage::getModel('catalog/category')->getCollection();
            $storeId = Mage::app()->getStore()->getId();
            /* @var $collection Mage_Catalog_Model_Resource_Eav_Mysql4_Category_Collection */
            $collection->addAttributeToSelect('name')
                ->addAttributeToSelect('is_active')
                ->setProductStoreId($storeId)
                ->setLoadProductCount(true)
                ->setStoreId($storeId);
            $productsCount = array();
            foreach($collection as $cat)
            {
                $productsCount[$cat->getId()] = array(
                    'name' => $cat->getName(),
                    'product_count' => $cat->getProductCount(),
                );
            }
            #Mage::log($productsCount);
            $this->_productsCount = $productsCount;
        }
        return $this->_productsCount;
    }

    [REST OF CODE OMITTED FOR BREVITY]
}

Best Answer

Best practice in Magento is to not use private methods at all but now you have to deal with it so here we go.

The problem is, you cannot just override a private method in your class because there will be two different methods (your class does not know about the existence of the original private method):

WP_CustomMenu_Block_Navigation::_isCategoryDisplayed()
Creed_CustomMenu_Block_Navigation::_isCategoryDisplayed()

and dependent on the class from where _isCategoryDisplayed() is called, one or the other will be used.

So your best choice is usually to override all methods that call the private method you change and replace the call. To avoid confusion and make further extension easier I would choose a different name for the new method and make it protected. Yes, this means much more duplicated code than if the method was not private in the first place.

It is also possible to change visibility with Reflection and have less duplication as a result but this is also an ugly hack so I don't recommend it if you don't know exactly what you are doing, so no details here. Don't try this at home, kids

Related Solutions

Magento – Toolbar not displaying with overridden Mage_Catalog_Block_Product_List

Without actually running your code, the reasons for this can be difficult to find.

This is not a solution for the actual issue, but a description on how to debug this type of issue. I hope it helps you towards solving the issue. I hope it also shows to others how important it is to use breakpoints with a debugger to solve a lot of magento 'why the f**ck is this not working' issues.

Are you using a debugger? This type of issue is easy to solve if you use a debugger, and step through the code, and check all the variables, values etc. Without this you are really just taking pot shots in the dark.

btw, I use netbeans with xdebug. (just in case you need a solution for that ;) )

Now, that all said, this is how I would start with the debug of this.

In list.phtml the toolbar is fetched via the code <?php echo $this->getToolbarHtml() ?>, thus I would start by whacking a breakpoint on that line, and then step into the routine to find why...

ok, so stepping in, I find this code:

/**
     * Retrieve list toolbar HTML
     *
     * @return string
     */
    public function getToolbarHtml()
    {
        return $this->getChildHtml('toolbar');
    }

thus, is the child block attached?

enter image description here

yes it is, so that is not the issue. Lets see what template is used for this block. Using the debugger, I can expand the toolbar child block, and view all its properties/values etc. The template is:

enter image description here

So, lets go do a break point in that file, and see code flow from there...

The first line of code in that template is <?php if($this->getCollection()->getSize()): ?>

Using the debugger, I can step over this line, and confirm it evaluates to true, if not ? why not....

And here my example ends, as the line in the tolbar could be your issue....

I hope this example helps, and show you how important it is to use a real debugger when coding with magento (or any application for that matter) :)

Using breakpoints, and stepping through the code, and actually have the ability to view all the classes/objects/values etc during a run, makes it pretty easy to solve this type of issue.

Have fun :)

Magento 1 – How to Override/Rewrite a Block Class

Every block, or group of blocks is declared in the config.xml file of a module like this (inside the <global> tag).
Here is an example from the catalog module

    <blocks><!-- marks definition of a block group -->
        <catalog><!-- unique alias for blocks in the module -->
            <class>Mage_Catalog_Block</class><!-- class prefix for all blocks -->
        </catalog>
    </blocks>

This means that a block can be instantiated using the alias catalog/class_name_here where class_name_here is the rest of the class path starting from the prefix.
This means catalog/class_name_here will be mapped by default to Mage_Catalog_Block_Class_Name_Here.

To rewrite a block you need to create a module that depends on the module you are trying to change (Magento_Catalog) in my example.
And you need to add this in the config.xml under the <global> tag.

<blocks>
    <catalog><!-- alias of the block group you are rewriting -->
        <rewrite><!-- reserved tag: specify that you are rewriting something -->
             <class_name_here>YourNamespace_YourModule_Block_Your_New_Class_Here</class_name_here> <!-- tag: the rest of the alias of the class you are rewriting. value: the name of your class that rewrites the core class -->
        </rewrite>
    </catalog>
</blocks>

Then create the class YourNamespace_YourModule_Block_Your_New_Class_Here (following the ZF folder structure) and make this class extend the original class.

class YourNamespace_YourModule_Block_Your_New_Class_Here extends Mage_Catalog_Block_Class_Name_Here
{
    //your awesome code here
}

When you are done, disable compilation and enable it again (if needed) and clear the cache.

This will not work for abstract blocks.
It only works for classes that get instantiated.

Example

Let's assume that you want to rewrite the file app\code\core\Mage\Catalog\Block\Product\View\Options\Type\Select.php which has the class Mage_Catalog_Block_Product_View_Options_Type_Select in your own module Marius_Test.

Then you would need this entry in your config.xml:

<blocks>
    <catalog>
        <rewrite>
            <product_view_options_type_select>Marius_Test_Block_Catalog_Block_Product_View_Options_Type_Select</product_view_options_type_select>
        </rewrite>
    </catalog>
</blocks>

app\code\local\Marius\Test\Block\Catalog\Product\View\Options\Type\Select.php:

class Marius_Test_Block_Catalog_Product_View_Options_Type_Select extends Mage_Catalog_Block_Product_View_Options_Type_Select
{
    //your awesome code here
}

Best Answer

Related Solutions

Magento – Toolbar not displaying with overridden Mage_Catalog_Block_Product_List

Magento 1 – How to Override/Rewrite a Block Class

Example

Related Topic