What is Magento EAV?

EAV stands for Entity, Attribute and Value.

Now what is this EAV means? We know that there are several table used in magento lets say we have a table Customer, this table would have several fields like first name, last name, email ID etc. and the values like Ashok, Sharma, ashok@somthing.com respectively. Now lets relate it with this EAV structure, here customer is an entity which has several attribute firstname, lastname and email ID and at last Ashok, sharma ect are values for the attributes.

Lets get into it deeply, in general scenario if we have an ecommerce application it will have several tables lets take an example of product table it will have all the information of a product and there will be another table for categories etc. So what we see is all the information of a product is in one table.

This is what magento doesn't follow. In magento product information is spread into several table. The core table for product is catalog_product_entity, if you see this table it doesn’t have any information of product which you have entered from admin panel except SKU. Now to get all details of product you have to join all attribute to the product entity table, to get product attribute go to the table eav_attribute. If you closely see this table there are lot of attributes so to distinguish product attribute see the field entity_type_id, since each entity has its unique entity_type_id, using this you can get load the attributes of product.

Now you have both entity and attribute its time to get values of the attributes, values are also separated across several table like all the string type values will be stored in catelog_product_varchar table, price will be stored in catelog_product_entity_decimal tables and so on.

So what we come to know from above is that EAV is much more scalable than normal database structure, this mean if we have to add any new field in product we don’t have to change the database table structure, what we do we create an attribute for that and insert values for it.

Hope this will be helpful.

Useful Codes in magento

Redirection in Magento Controllers.

Mage::app()->getResponse()->setRedirect(Mage::getUrl('customer/account/login')); 

How to run an custom query in magento?

$sql = "SELECT * FROM your_table"; 

$getData = Mage::getSingleton('core/resource') ->getConnection('core_read')->fetchAll($sql); 

foreach($getData as $row) { 

    echo $row['name'] . "\n"; 

} 

// fetch write database connection that is used in Mage_Core module 

$write = Mage::getSingleton('core/resource')->getConnection('core_write'); 

// now $write is an instance of Zend_Db_Adapter_Abstract 

$write->query("insert into yourtablename values ('val1','val2')");

//or you can do it like this 

$write = Mage::getSingleton('core/resource')->getConnection('core_write'); 

$sql  = "insert into yourtablename values (?, ?)"; 

$write->query($sql, array('val1','val2'));

Get Customer Data

$customerData = Mage::helper('customer')->getCustomer()->getData());

Some Code Samples In Magento

Get CMS Page ID
$pageId = Mage::getBlockSingleton('cms/page')->getPage()->getIdentifier();

How to get product attributes?
<?php echo $_product->getResource()->getAttribute('attribute name')->getFrontend()->getValue($_product) ?>

How to show breadcrumbs in magento?
<?php echo $this->getLayout()->getBlock("breadcrumbs")->toHtml(); ?>

How to show Static Blocks?
<?php /* $this->block_code2call, static block code name - the one added under CMS > Static Blocks */ $_block = Mage::getModel('cms/block') ->setStoreId(Mage::app()->getStore()->getId()) ->load($this->getLayout()->createBlock('cms/block')->setBlockId($this->block_code2call)->getBlockId()); ?>

Get current category
Mage::getModel('catalog/layer')->getCurrentCategory()->getName()

Magento Custom Category Listing Block

<?php
$cats = Mage::getModel('catalog/category')->load(2)->getChildren();
$catIds = explode(',',$cats);
?>
<ul>
<?php foreach($catIds as $catId): ?>
<li>
<?php
$category = Mage::getModel('catalog/category')->load($catId);
echo $category->getName();
$subCats = Mage::getModel('catalog/category')->load($category->getId())->getChildren();
$subCatIds = explode(',',$subCats);
?>
<?php if(count($subCatIds) > 1):?>
<ul>
<?php foreach($subCatIds as $subCat) :?>
<li>
<?php
$subCategory = Mage::getModel('catalog/category')->load($subCat);
echo $subCategory->getName();
?>
</li>
<?php endforeach;?>
</ul>
<?php endif; ?>
</li>
<?php endforeach; ?>
</ul>

The XML Block Code:

<block type="catalog/navigation" name="catalog.category" template="catalog/navigation/category.phtml" />

How to check current page is Homepage in magento

<?php if(Mage::getSingleton('cms/page')->getIdentifier() == 'home' && Mage::app()->getFrontController()->getRequest()->getRouteName() == 'cms') :
echo “Home Page”;
else:
echo “Not Home Page”;
endif;
?>

Adding Products To The Home Page Of Magento

You will need to add some code to your home page in order to display all products you have specified as new. Go to CMS->Manage Pages and select the home page to edit.

Add this code to underneath your page title.

{{block type=”catalog/product_new” name=”home.catalog.product.new” alias=”product_homepage” template=”catalog/product/new.phtml”}}

Go check your homepage and your product will be displayed there.
For more please visit the below link.
How To - Display products on home page

Code to get store's skin to create a full url

$this->getSkinUrl('images/img_name.jpg')

OR

<img scr="{{skin url=images/img_name.jpg}}” width="220" height="180"/>

Magento Admin Login not working on Localhost.

Here is the simple fix to override this problem.
This is for Magento v1.3.2.4 :

Open this file,
app/code/core/Mage/Core/Model/Session/Abstract/Varien.php
and find the    session_set_cookie_params(line-78) and replace your code with this ;

session_set_cookie_params(
$this->getCookie()->getLifetime(),
$this->getCookie()->getPath()
//$this->getCookie()->getDomain(),
//$this->getCookie()->isSecure(),
//$this->getCookie()->getHttponly()  

also remove the comma from end of getPath().

This is for Magento v1.4.0.1 :Open up Varien.php at magentoappcodecoreMageCoreModelSessionAbstract and find the following snippet starting at line 77:

// session cookie params
$cookieParams = array(
'lifetime' => $cookie->getLifetime(),
'path' => $cookie->getPath(),
'domain' => $cookie->getConfigDomain(),
'secure' => $cookie->isSecure(),
'httponly' => $cookie->getHttponly()
);

if (!$cookieParams['httponly']) {
unset($cookieParams['httponly']);
if (!$cookieParams['secure']) {
unset($cookieParams['secure']);
if (!$cookieParams['domain']) {
unset($cookieParams['domain']);
}
}
}

if (isset($cookieParams['domain'])) {
$cookieParams['domain'] = $cookie->getDomain();
}
  Now comment out the relevant parts like so:// session cookie params
$cookieParams = array(
'lifetime' => $cookie->getLifetime(),
'path' => $cookie->getPath(),
'domain' => $cookie->getConfigDomain(),
'secure' => $cookie->isSecure(),
'httponly' => $cookie->getHttponly()
);

/* if (!$cookieParams['httponly']) {
unset($cookieParams['httponly']);
if (!$cookieParams['secure']) {
unset($cookieParams['secure']);
if (!$cookieParams['domain']) {
unset($cookieParams['domain']);
}
}
}

if (isset($cookieParams['domain'])) {
$cookieParams['domain'] = $cookie->getDomain();
}*/

How to show new products on home page?

There are many ways to show products on home page.

Go to "CMS - Manage Pages" and select "Home Page" from the list of pages.

Use this code to show products as "New Products" on your home page:

{{block type="catalog/product_new" name="home.catalog.product.new" alias="product_homepage" template="catalog/product/new.phtml"}}

(Note that you must have some new products in your catalogue for anything to show when you do this. In this context new doesn’t mean that you’ve recently added them; only products explicitly marked as new using ‘Set Product as New from Date’ and ‘Set Product as New to Date’ options in the ‘General’ product information page in the admin tool will be shown.)

Code to get the Categories list in magento.

Below code can be used to get the categories tree in magento

require_once $_SERVER[‘DOCUMENT_ROOT’]."/app/Mage.php";
Mage::app(’1’);

function nodeToArray(Varien_Data_Tree_Node $node)
{
$result = array();
$result[’category_id’] = $node->getId();
$result[’parent_id’] = $node->getParentId();
$result[’name’] = $node->getName();
$result[’is_active’] = $node->getIsActive();
$result[’position’] = $node->getPosition();
$result[’level’] = $node->getLevel();
$result[’children’] = array();

foreach ($node->getChildren() as $child) {
$result[’children’][] = nodeToArray($child);
}

return $result;
}
function load_tree() {

$tree = Mage::getResourceSingleton(’catalog/category_tree’)
->load();
$store = 1;
$parentId = 1;
$tree = Mage::getResourceSingleton(’catalog/category_tree’)
->load();

$root = $tree->getNodeById($parentId);

if($root && $root->getId() == 1) {
$root->setName(Mage::helper(’catalog’)->__(’Root’));
}

$collection = Mage::getModel(’catalog/category’)->getCollection()
->setStoreId($store)
->addAttributeToSelect(’name’)
->addAttributeToSelect(’is_active’);

$tree->addCollectionData($collection, true);
return nodeToArray($root);

}

function print_tree($tree,$level) {
$level ++;
foreach($tree as $item) {
echo str_repeat("    ", $level).$item[’name’]."<br>";
print_tree($item[’children’],$level);
}
}

$tree = load_tree();
print_tree($tree[’children’],0);