How to remove shipping using observer for checkout in magento? - magento

Question

My Problem:
I want to use observer before checkout onepage page begins, in that, based on products in the cart, I want to disable shipping if it doesn't match certain conditions.
I am using [controller_action_predispatch_checkout_onepage_index] event observer, this basically call before checkout page starts loading...I am able to get all products and quote info but didn't found any method to disable shipping.
What I am looking for,
from the observer, is it possible to disable shipping by calling certain magento methods or any other solutions?
Overriding collectRates()
After getting few replies, I am trying to override collectRates() method using code given below
$method = Mage::getModel('shipping/rate_result_method');
$method->setCarrier('flatrate');
$method->setCarrierTitle($this->getConfigData('title'));
$method->setMethod('flatrate');
$method->setMethodTitle($this->getConfigData('name'));
if ($request->getFreeShipping() === true || $request->getPackageQty() == $this->getFreeBoxes()) {
$shippingPrice = '0.00';
}
$method->setPrice($shippingPrice);
$method->setCost($shippingPrice);
$result->append($method);
Although, I dont want to enable flatrate shipping method either. I just want to disable shipping, or optionally return with reply something like
Free shipping $0.00
User can select that to continue to next step. Please help me from here..
What should I use in $method->setCarrier('??????');
or what changes I do need to do in above code?

Answer 1

I think it might be better to either override or subclass the individual Carrier models.
All carriers implement a method "Mage_Shipping_Model_Carrier_Abstract::collectRates()" to return results.
It is possible to get information about the current quote to modify the returned rates/options from within this method.
That said, if there is a way to do it with an observer, it would probably be cleaner/easier.

Answer 2

Finally I have override shipping method, its a two step code but you can reduce it to one step if you wish. Here is my two step solution.
Before we start our shipping class needs to extend and implement
extends Mage_Shipping_Model_Carrier_Abstract
implements Mage_Shipping_Model_Carrier_Interface
Now, We create a protected method
protected function _createMethod($request, $method_code, $title, $price, $cost)
{
$method = Mage::getModel('shipping/rate_result_method');
$method->setCarrier('australiapost'); // in my case its australia post, it can be any other whatever you are using
$method->setCarrierTitle($this->getConfigData('title'));
$method->setMethod($method_code);
$method->setMethodTitle($title);
$method->setPrice($this->getFinalPriceWithHandlingFee($price));
$method->setCost($cost);
return $method;
}
Now just use code below to create new method with free shipping and bypass existing shipping calculator, this code will go inside collectRates(Mage_Shipping_Model_Rate_Request $request) method
// PROCESS WILL RETURN FREE SHIPPING
if ($request->getFreeShipping() === true || $request->getPackageQty() == $this->getFreeBoxes()) {
$shippingPrice = '0.00';
}
$shipping_method = 'Free Shipping';
$method = $this->_createMethod($request, $shipping_method, 'Shipping Disabled', '0.00', '0.00');
$result->append($method);
return $result;
By Doing this, you can get result like below in checkout and user can easily click continue to next step.
Shipping Disabled $0.00