Magento - custom admin grid issue - php

Question

I've been writing a custom out of stock module for the magento backend, I have mass actions, export etc working. However when i do any sort of search function (like put something in the product name field) and indeed try to change to the next page (or input a specific page into the field) or how many products appear on a page. It immediately redirects me to the dashboard.
Can anyone point me in the right direction as to where the code is that handles this function? I'm going to assume its part of the controller, but i've been searching for the last hour and is now time to ask for help!!
Thanks for any help you can provide!
Prepare columns function:
protected function _prepareColumns()
{
$this->addColumn('sku',
array(
'header'=> Mage::helper('catalog')->__('SKU'),
'width' => '80px',
'index' => 'sku',
));
$sets = Mage::getResourceModel('eav/entity_attribute_set_collection')
->setEntityTypeFilter(Mage::getModel('catalog/product')->getResource()->getTypeId())
->load()
->toOptionHash();
$this->addColumn('set_name',
array(
'header'=> Mage::helper('catalog')->__('Attrib. Set Name'),
'width' => '60px',
'index' => 'attribute_set_id',
'type' => 'options',
'options' => $sets,
));
$store = $this->_getStore();
if ($store->getId()) {
$this->addColumn('custom_name',
array(
'header'=> Mage::helper('catalog')->__('Name in %s', $store->getName()),
'index' => 'custom_name',
));
}
$this->addColumn('name',
array(
'header'=> Mage::helper('catalog')->__('Name'),
'index' => 'name',
));
$this->addColumn('stock_status',
array(
'header'=> 'Availability',
'width' => '60px',
'index' => 'stock_status',
'type' => 'options',
'options' => array('1'=>'In stock','0'=>'Out of stock'),
));
$this->addColumn('custom_stock_status',
array(
'header' => 'Custom Stock Status',
'width' => '60px',
'index' => 'custom_stock_status',
'type' => 'options',
'editable' => 'true',));
$this->addColumn('eol',
array(
'header'=> Mage::helper('catalog')->__('EoL'),
'width' => '20px',
'type' => 'checkbox',
'index' => 'eol',
'onclick' => 'this.value = this.checked ? 1 : 0;',
'values' => array('1','2'),
'editable' => 'true',
));
$store = $this->_getStore();
$this->addColumn('qty',
array(
'header'=> Mage::helper('catalog')->__('Qty'),
'width' => '25px',
'type' => 'number',
'index' => 'qty',
));
$this->addColumn('status',
array(
'header'=> Mage::helper('catalog')->__('Status'),
'width' => '70px',
'index' => 'status',
'type' => 'options',
'options' => Mage::getSingleton('catalog/product_status')->getOptionArray(),
));
$this->addColumn('action',
array(
'header' => Mage::helper('catalog')->__('Action'),
'width' => '90px',
'type' => 'action',
'getter' => 'getId',
'actions' => array(
array(
'caption' => Mage::helper('catalog')->__('Edit Product'),
'url' => array(
'base'=>'store_admin/catalog_product/edit',
'params'=>array('store'=>$this->getRequest()->getParam('store'))
),
'field' => 'id'
)
),
'filter' => false,
'sortable' => false,
'index' => 'stores',
));
$this->addRssList('rss/catalog/notifystock', Mage::helper('catalog')->__('Notify Low Stock RSS'));
return parent::_prepareColumns();
}
Furthermore i'm trying to filter by an attribute, I need to filter the same attribute twice in order to output both null and no attributes, but not yes. Is there anyway to do this?
->addAttributeToFilter('eol', array('null' => true), 'left')
->addAttributeToFilter('eol', array('No' => true));
This is what i'm trying to do at the moment, however, it doesn't work in the slightest. Both work individually fine!

Answer 1

Mage_Adminhtml_Block_Widget_Grid
has a method
_addColumnFilterToCollection($column)
You can override it to implement filtering logic for your custom grid.

Answer 2

For CE 1.6.2, this worked for me:
1) Copy over app/code/core/Mage/Adminhtml/Block/Catalog/Product/Grid.php to app/code/local/Mage/Adminhtml/Block/Catalog/Product/Grid.php
2) add the code below from app/code/local/Mage/Adminhtml/Block/Catalog/Product/Grid.php inside/under _prepareCollection()
AFTER ->addAttributeToSelect('type_id'); and before if (Mage::helper('catalog')->isModuleEnabled('Mage_CatalogInventory')) {
CODE:
$collection->joinTable( 'cataloginventory/stock_item',
'product_id=entity_id', array("stock_status" => "is_in_stock") )
->addAttributeToSelect('stock_status');
3) Add the below around line 180 after
'index' => 'price', ));
CODE:
$this->addColumn('stock_status',
array(
'header'=> 'Stock Status', // this is the title of the column
'width' => '60px', // this is the width of the column
'index' => 'stock_status',
'type' => 'options',
'options' => array('1'=>'In Stock','0'=>'Out Of Stock'),
)
);