In this article, we are going to discuss about How to implement memcache in CodeIgniter (CI). Memcache is used to increase the performance of the websute (ie, speed-up the website) by using the memory space of our used domains and store the database query results in that cache and minimise the application-database interaction.

Step 1:

Before we implement Memcache in CodeIgniter (CI), we need to check whether the memcache is enabled in our web server or not. If it is not enabled, then enable it by uncomment the 'extension=php_memcache.dll' in php.ini file in the server. (Just remove the ";" symbol infront of the line).

Step 2:

Download the Memcache executable file to install the Memcache in the webserver. To download the Memacache executable file, Click on the below link

Download link - http://code.jellycan.com/files/memcached-1.2.6-win32-bin.zip

Step 3:

Once downloaed, Unzip the downloaded file, you will get a memcached executable file. Store that in a web server to install.

Step 4:

Then open the command prompt and run this command

c:/xampp/htdocs/memcached.exe -d install

then run the below command

'c:/xampp/htdocs/memcached.exe -d start'

Step 5:

Download the cache driver from the below URL

http://d45jz936mo8n8.cloudfront.net/wp-content/uploads/2010/01/Cache.php_1.zip

Once downloaded, Unzip and place the cache.php in system/libraries/cache folder.

Step 6:

Create an empty folder named "cache" on the location system folder.

Step 7:

Load the Cache driver in controller CodeIgniter (CI) application

$this->load->driver('cache');

Add the following lines of code where needed to cache the query result.

$cache = $this->cache->get('cache_data');
if($cache)
{
  $data = $this->cache->get('cache_data');
}
else
{
   $data = $this->sample_model->get_data();
   $this->cache->save('cache_data', $data, NULL, 3600);
}

While accessing the webpage, it will execute query on the database for the first time, then the result will be stored in cache upto the refreshing time given in the save() function above.

So until the time exceeds, whenever the user refreshes the page, the application will not interact with the database. instead it will retrieve from cache and display.

This caching is applicable only for the select queries and the static updates.

In this article we are going to discuss about, How to execute Cron Job in CodeIgniter (CI) using PHP. Codeigniter (CI) runs based on the front controller pattern where all the requests are routed using the index.php file. So we need to go through the routing procedures  to execute any code on CodeIgniter (CI) application. Basically if we need to run cron job, we need to create the code files and placed it in the server and call the files in the cron job using path to files.

But in CodeIgniter (CI) applications, it is not much easy to call the cron job files and use CodeIgniter models inside this scripts. You need to load all the required models and files manually. We cannot achieve this using normal php script calling procedure.

Curl:

PHP Curl extension is used to transfer data from server to another server using various methods. In this example we need to execute a remote url using normal http method in curl.

Steps to install Curl in Windows:

You have to allow the curl extension by removing ';' in the php.ini file and restart apache server.

Steps to install Curl in Fedora:

Type the following command in the terminal using the super user.

yum install php-curl

Steps to install Curl in Ubuntu:

Type the following command in the terminal using the super user.

apt-get install php-curl

Setting the Cronjob using Curl

You can set up the cronjob to call the CodeIgniter (CI) url using the following line of code.

/usr/bin/curl http://www.example.com/controller/cron_function


Open the crontab using the terminal and enter the above line of code and restart the cron. Use the path to the curl file according to your installed location. Call the cron function of your site remotely using http.

Normally we are all experienced with connecting the database with Magento. But in this article, we are going to discuss about How to create an external database connection in Magento. Hopefully, by presenting this code here, I can save you from the pain I endured :)

Creating a database Connection

To create a new connection, create a custom module and add the following codes to your config.xml. The code below is needed to get the external database connection working.

<?xml version="1.0"?>
<config>
    <modules>
        <PHPCmsframework_Externaldb>
            <version>0.1.0</version>
        </PHPCmsframework_Externaldb>
    </modules>
    <global>
        <resources>
            <externaldb_write>
                <connection>
                    <use>externaldb_database</use>
                </connection>
            </externaldb_write>
            <externaldb_read>
                <connection>
                    <use>externaldb_database</use>
                </connection>
            </externaldb_read>
            <externaldb_setup>
                <connection>
                    <use>core_setup</use>
                </connection>
            </externaldb_setup>
            <externaldb_database>
                <connection>
                    <host><![CDATA[localhost]]></host>
                    <username><![CDATA[db_username]]></username>
                    <password><![CDATA[db_password]]></password>
                    <dbname><![CDATA[db_name]]></dbname>
                    <model>mysql4</model>
                    <type>pdo_mysql</type>
                    <active>1</active>
                </connection>
            </externaldb_database>
        </resources>
    </global>
</config>

Clear the cache after creating your new module and from now on, each time you load Magento, a second database connection will be created.

Accessing an external Database

When I initially checked out how to create an external database connection, I was using Zend_Db to retrieve all of my information. You can use the following to test your database connection is working:

<?php
    $resource   = Mage::getSingleton('core/resource');
    $conn       = $resource->getConnection('externaldb_read');
    $results    = $conn->query('SELECT * FROM tblName');
     
    print_r($results);

The above code is working fine, however kind of takes the point away from having this connection available in Magento.

Accessing an External Database Using Models

Using models to access the database keeps our code style uniform throughout Magento. Also, it means we can integrate any other CMS or database driven application without learning it's coding practices. To achieve this, simply add models to your custom module like you would for any other module.


I will attempt to demonstrate how to set up the models and config.xml files now.

Creating The Model Class Files

Create the following files:

code/local/PHPCmsframework/Externaldb/Model/Book.php

<?php
class PHPCmsframework_Externaldb_Model_Book extends Mage_Core_Model_Abstract
{
    public function _construct()
    {
        $this->_init('externaldb/book');
    }
}

code/local/PHPCmsframework/Externaldb/Model/Mysql4/Book.php


<?php
class PHPCmsframework_Externaldb_Model_Mysql4_Book extends Mage_Core_Model_Mysql4_Abstract
{
    public function _construct()
    {
        $this->_init('externaldb/book', 'book_id'); // book_id refers to the primary key of the book table
    }

} 

code/local/PHPCmsframework/Externaldb/Model/Mysql4/Book/Collection.php

<?php
class PHPCmsframework_Externaldb_Model_Mysql4_Book_Collection extends Mage_Core_Model_Mysq4_Collection_Abstract
{
    public function _construct()
    {
        $this->_init('externaldb/book');
    }

}

That's the minimum needed for your models to be able to access an external database!

Adding the Models to The Config


To inform Magento about our models, we need to register them in config.xml. Below is an updated version of config.xml with the models for Book registered.

<?xml version="1.0"?>
<config>
    <modules>
        <PHPCmsframework_Externaldb>
            <version>0.1.0</version>
        </PHPCmsframework_Externaldb>
    </modules>
    <global>
        <models>
            <externaldb>
                <class>PHPCmsframework_Externaldb_Model</class>
                <resourceModel>externaldb_mysql4</resourceModel>
            </externaldb>
            <externaldb_mysql4>
                <class>PHPCmsframework_Externaldb_Model_Mysql4</class>
                <entities>
                    <book>
                        <table>library_book</table>
                    </book>
                </entities>
            </externaldb_mysql4>
        </models>
        <resources>
            <externaldb_write>
                <connection>
                    <use>externaldb_database</use>
                </connection>
            </externaldb_write>
            <externaldb_read>
                <connection>
                    <use>externaldb_database</use>
                </connection>
            </externaldb_read>
            <externaldb_setup>
                <connection>
                    <use>core_setup</use>
                </connection>
            </externaldb_setup>
            <externaldb_database>
                <connection>
                    <host><![CDATA[localhost]]></host>
                    <username><![CDATA[db_username]]></username>
                    <password><![CDATA[db_password]]></password>
                    <dbname><![CDATA[db_name]]></dbname>
                    <model>mysql4</model>
                    <type>pdo_mysql</type>
                    <active>1</active>
                </connection>
            </externaldb_database>
        </resources>
    </global>
</config>

That's it, the models should now be registered in Magento!

Testing The Models


Testing them is easy enough, just treat them like normal Magento models.

<?php
    // Load the book with a primary key value of 4
    $_book = Mage::getModel('externaldb/book')->load(4);

    // This would print out the value in the field isbn in the external database
    echo $_book->getIsbn();

    //You can even update records!
    $_book->setName('1984');
    $_book->setAuthor('George Orwell');

    try {
      $_book->save();
    } catch (Exception $e) {
      exit($e->getMessage());
    } 

This is one of my favaourite article. So I probably haven't written this up as well as I could have, however, I think that using a second database in Magento can be extremely useful. 

In this article, we are going to discuss about How to load a categort or a product by an attribute. Most of the developers are often searching for how to load a product by a particular attribute. This article is quite easy to achieve this in Magento and can be done using Magento collections.

Load a Product By SKU

In magento, we have lot of pre defined product attributes. SKU is a static attribute. This means that instead of being stored in one of the products EAV tables, it is stored in the main product entity table (catalog_product_entity). This makes loading a product based on it's SKU much easier and efficient.

<?php
    $sku = 'my-product-sku';
    $product = Mage::getModel('catalog/product')->load($sku, 'sku');
    if ($product->getId()) {
        echo $product->getName();
    }
    else {
        echo 'Product not found with SKU of ' . $sku;
    }

The above code is used to makes the use of load method, which is available for all EAV entities in Magento. By default this method takes two parameters:

1. A value that is used to match the product and the field that the values is checked against.
2. If the second parameter is empty, Magento will use the primary key, which is usually the model ID. By passing a static attribute (SKU is the only useful static attribute for this context), it is possible to load a product model on a different value.