How to format weight to display 2 decimal places in Orders Grid?

Question

Currently my Orders Grid is set up to add a Weight column with the total order weight, but it is displaying with 4 decimal places and I would like to only display 2 decimal places.

_prepareCollection

$collection = Mage::getResourceModel($this->_getCollectionClass());
$collection->getSelect()->joinInner(array('order_address' => Mage::getSingleton('core/resource')->getTableName('sales_flat_order_address')),'order_address.parent_id = main_table.entity_id',array('company','telephone'))->group('order_address.parent_id');
$collection->getSelect()->join(array('sfo'=>'sales_flat_order'),'sfo.entity_id=main_table.entity_id',array('sfo.customer_email','sfo.weight')); 
$this->setCollection($collection);

_prepareColumns

...
$this->addColumn('weight', array(
        'header' => Mage::helper('sales')->__('Weight'),
        'index' => 'weight',
        'filter_index' => 'sfo.weight',
        'width' => '50px',
));
...

What is the proper way to format the data in the grid?

Answer 1

There are a couple of ways to do it.

SQL-level

$collection->getSelect()
    ->columns(array('weight' => new Zend_Db_Expr("DECIMAL(weight, 2)")));

Here we re-define the weight column in the selection object to select weight as a float rounded to the nearest hundredth.

Application-level

# Your block, _prepareColumns method
$this->addColumn('weight', array(
        'header' => Mage::helper('sales')->__('Weight'),
        'index' => 'weight',
        'filter_index' => 'sfo.weight',
        'width' => '50px',
        'renderer' => 'yourmodule/adminhtml_grid_renderer_yourblock',
                         |
));                      |
                         |
# Your renderer block <--|
class Namespace_Yourmodule_Block_Adminhtml_Grid_Renderer_Yourblock
    extends Mage_Adminhtml_Block_Widget_Grid_Column_Renderer_Abstract
{

    // Where $row is an order model
    public function render(Varien_Object $row)
    {
        return number_format($row->getWeight(), 2);
    }

}

Here we leverage Magento's column renderer feature to pass each row of the grid (order model in this case) through a custom block to manipulate and return the display value.

Answer 2

try adding 'type' => 'number',

...
$this->addColumn('weight', array(
        'header'    => Mage::helper('sales')->__('Weight'),
        'index'     => 'weight',
        'type'      => 'number', //This Line
        'filter_index' => 'sfo.weight',
        'width' => '50px',
));
...

Answer 3

In database, weight attribute have backend_type set to decimal.

To change the decimal precision of attributes that have a backend_type set to decimal,

You have to change the type of value in this table :

catalog_product_entity_decimal

If you have not change yet, you should see :

decimal(12,4)

In your case, you have to replace with

decimal(12,2)