Js and Css For Static Block - MAGENTO EXTENSION

Static blocks are very useful tools in Magento. We can effectively use them in different situations. They provide us enough power on content management. However I felt it lacks with something. It can show its content only in boring text format. If we are planning to use multiple static blocks in a page, then we will definitely seek for adding css and js for static block contents. However if we are planning to do it in the most effective way, we can't achieve this functionality in one step. For this small (some time big) headache, I decided to make an end. It results in a tiny magento extension Rkt_JsCssforSb.

What it does

This extension functionality is simple. For every static block, you can see a section for put javascript and css. You need to put css and js in those text areas. Rest will do by the extension. You don't need to put script and style html tag enclosures inside text area. This job will effectively carry out by extension. Css that added for static blocks will get append to head section and scripts will go to bottom section in body part.

In deep

Static block are least considered section in magento code wise !. I am telling this because, during the development of this extension, I have found out that, there are no static block specific events available. However cms pages has lot of events available. Also model of static block is somewhat "weak" when compare with other entity models! For example, there is no event prefix available for static blocks. This made me in serious trouble and as a result, I have done a model rewrite during the development of the extension. I know its bad. But I forced to do it. Along with this, I am observing to three events in order to make the work done.

But I personally believe this extension is highly useful. Since it makes static block somewhat "dynamic". We can set css and make static block content look nice and by applying some js , we can make those contents dynamic etc.

I am waiting for your feedbacks about this extension. Currently the extension is available on GITHUB and soon it will available in Magento connect. Hope you will use it.

Useful Links

• http://stackoverflow.com/questions/17832914/how-do-i-extend-cms-block-on-save-event-of-magento
• http://magento.stackexchange.com/questions/32324/how-to-check-whether-a-block-exist-based-on-its-type

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The Way Magento Generates Helper Classes For Core Modules

Introduction
----------------------

When I started to do Module Development in Magento, a lot of time I got an error like this

 Fatal error: Class 'Mage_HelperReference_Helper_Data' not found

First time I wonder why Magento generates such an unwanted error, Since I really did't specify any helper anywhere in my code. But as time passes, I found out that, eventhough we don't use any helper assistance explicitly, Magento need its to be defined to do some of its operation. So in order to avoid this error, what we need to do is, define helper class for our Module and declare our helper class. Those two steps are as follows

Location : app/code/local/Namespace/Module/etc/config.xml

 
  
   
    
     Namespace_Module_Helper
    
   
  
 

Location: app/code/local/Namespace/Module/Helper/Data.php

class Namespace_Module_Helper_Data extends Mage_Core_Helper_Abstract{

}

The advantage of defining helper class is three according to my view

1. We can use this helper class almost everywhere in Magento, as helpers has a global view is provided by Magento

2. We can avoid un-necessary error popups as we discussed before

3. We can now call our helper with his alias name. In this case we can call this helper as

Mage::helper('my_helper_alias')

Why I wrote this blog
-----------------------

In recent past, I had a situation where I want to know the alias name for Mage_Sales_Helper_Data. So I looked in config.xml that is defined for Mage_Sales core module. Surprisingly, I couldn't find the helper definition of that class there !!!!

For curiosity I tried this code to know what would be the result

    print_r(get_class(my_helper_alias));

And it gave me this result

Mage_Sales_Helper_Data

So that means, somewhere Magento sets sales alias for Mage_Sales_Helper_Data. If that definition is not in config.xml, where would be it? So let us together find out where it is.

Jump into the situation
------------------------

Let us start with Mage::helper('sales'). We need to see what is inside the method helper() that is defined inside app/Mage.php in order find the mystery behind this. So helper() look like this.

public static function helper($name)

    {

        $registryKey = '_helper/' . $name;

        if (!self::registry($registryKey)) {

            $helperClass = self::getConfig()->getHelperClassName($name);

            self::register($registryKey, new $helperClass);

        }

        return self::registry($registryKey);

    }

In short, what this function does is, it creates an instances if a helper class as per the name that we passed to this function and register that instace global scope.Then it passes this helper instace to us.

Importance of the function :

Registration of our helper class is an important step. This is why all helper classes become globally available in Magento. In magento anything that present in Mage::registry() will be globally accessible for us.

I need your concentration at this point.

if (!self::registry($registryKey)) {

            $helperClass = self::getConfig()->getHelperClassName($name);

            self::register($registryKey, new $helperClass);

        }

Here it first check whether our helper is registered or not. If not it will call Mage_Core_Model_Config::getHelperClassName() method. Most probably it will return an instance of helper to us and then later it will registered in magento registry. So let us have a look on this method.

public function getHelperClassName($helperName)

    {

        if (strpos($helperName, '/') === false) {

            $helperName .= '/data';

        }

        return $this->getGroupedClassName('helper', $helperName);

    }

The purpose of this funciton is so simple, it actually checks whether passed value hold class name for helper. If not it will set helper class name as data. Then it invokes an another method getGroupedClassName() to return the proper class name.

Importance of the function :

The specularity of this function is very important to understand. This is where the mystery term Data came for helper classes. I will explain it little bit. Suppose we are calling our helper class somewhere in magento as like this

Mage::helper('my_helper_alias/helpername');

So magento looks for this alias name in the config tree. Magento generates a huge xml node tree by grabing content in all config.xml files that are available through all available Magento modules. This is what known as config tree. In that config tree, it will look for this helper_alias_name and find out that class that is defined for this alias is Namespace_Module_Helper. So magento got the location. It decides which file to grab from that location according to the second parameter passed. In this case it is helpername. So it will look for this file app/code/Namespace/Module/Helper/Helpername.php. What would be if we didn't specify the helper name via our method?

Mage::helper('my_helper_alias'); 

If the calss is not specified it will assume that class name is Data and hence look for that file. This

*ASSUMPTION

takes place actually in this place.

Now let us have a look on what would getGroupedClassName('helper', 'sales/data') return.

public function getGroupedClassName($groupType, $classId, $groupRootNode=null)

    {

        if (empty($groupRootNode)) {

            $groupRootNode = 'global/'.$groupType.'s';

        }

        $classArr = explode('/', trim($classId));

        $group = $classArr[0];

        $class = !empty($classArr[1]) ? $classArr[1] : null;

        if (isset($this->_classNameCache[$groupRootNode][$group][$class])) {

            return $this->_classNameCache[$groupRootNode][$group][$class];

        }

        $config = $this->_xml->global->{$groupType.'s'}->{$group};

        // First - check maybe the entity class was rewritten

        $className = null;

        if (isset($config->rewrite->$class)) {

            $className = (string)$config->rewrite->$class;

        } else {

            /**

             * Backwards compatibility for pre-MMDB extensions.

             * In MMDB release resource nodes <..._mysql4> were renamed to <..._resource>. So is left

             * to keep name of previously used nodes, that still may be used by non-updated extensions.

             */

            if (isset($config->deprecatedNode)) {

                $deprecatedNode = $config->deprecatedNode;

                $configOld = $this->_xml->global->{$groupType.'s'}->$deprecatedNode;

                if (isset($configOld->rewrite->$class)) {

                    $className = (string) $configOld->rewrite->$class;

                }

            }

        }

        // Second - if entity is not rewritten then use class prefix to form class name

        if (empty($className)) {

            if (!empty($config)) {

                $className = $config->getClassName();

            }

            if (empty($className)) {

                $className = 'mage_'.$group.'_'.$groupType;

            }

            if (!empty($class)) {

                $className .= '_'.$class;

            }

            $className = uc_words($className);

        }

        $this->_classNameCache[$groupRootNode][$group][$class] = $className;

        return $className;

    }

First this function generates 3 values depend upon the values provided. They are group root node, groupname and class name.

group root node :-

This will be the reference to a child node that comes under global node in configuration tree. For helper value will be global/helpers. For models it will be globals/models and so on

Group name :-

This will be a reference to a node that comes under a group root node in configuratio tree.

class name :-

this would be reference to the class name that comes under group in configuratio tree
So after generating those values, this function mainly do 3 things

1. Check whether an entry exist based on group root, group, class in cache of the system. If yes it will retrieve data from there and returns it. This is what happens here

    if (isset($this->_classNameCache[$groupRootNode][$group][$class])) {

            return $this->_classNameCache[$groupRootNode][$group][$class];

        }

2. Check whether any rewrite exist for the class and if it is there, then return that class. In our case, this is not relevant. So I skip this step. < br /> 3. If both of above step fails, now function tries to genearate a class name and then return that class name. This is the important section for us. Because in this section where magento generates helper class name for core modules. So let us look on that portion of code.

    if (empty($className)) {

            if (!empty($config)) {

                $className = $config->getClassName();

            }

            if (empty($className)) {

                $className = 'mage_'.$group.'_'.$groupType;

            }

            if (!empty($class)) {

                $className .= '_'.$class;

            }

            $className = uc_words($className);

        }

        $this->_classNameCache[$groupRootNode][$group][$class] = $className;

        return $className;

Here first it checks is there any class name defintion for the helper requested in configuration tree. For core modules, this condtion fails. That is because core modules do not possess helper class definition in config gile. Now you can see magento generates our class name. ie

            if (empty($className)) {

                $className = 'mage_'.$group.'_'.$groupType; //mage_sales_helper

            }

            if (!empty($class)) {

                $className .= '_'.$class; //mage_sales_helper_data

            }

            $className = uc_words($className); //Mage_Sales_Helper_Data

Now this value passes to helper() in Mage.php. Then it will create an instane of this class and also register this class in registry. Hence on the other side, we will get a helper instace Mage_Sales_Helper_Data.

RESULT
----------

So remember the

helper alias for a core module in Magento will be its module name itself.

For Mage_Sales => sales
For Mage_Catalog => catalog
For Mage_Customer => customer

and so on.

Hope you enjoy this !

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