Disable payment options-only cash on delivery for particular product-magento

Question

I am using Magento 1.4.1.1 and i want to disable payment option for some products.i want to show only Cash on Delivery method for some products and need to hide other.

Answer 1

First create a product attribute (name : 'magepal_payment_filter_by_product', type : yes/no) to identify these products.

E.g base of Magento v1.7 you could

1. Auto enable payment module programmatically see https://stackoverflow.com/a/14023210/1191288

2. Enable all applicable payment module and filter which module to show where

In /app/code/local/MagePal/PaymentFilterByProduct/etc/config.xml

<?xml version="1.0"?>
<config>
    <modules>
        <MagePal_PaymentFilterByProduct>
            <version>1.0.1</version>
        </MagePal_PaymentFilterByProduct>
    </modules>
    <global>
        <helpers>
            <paymentfilterbyproduct>
                <class>MagePal_PaymentFilterByProduct_Helper</class>
            </paymentfilterbyproduct>
            <payment>
                <rewrite>
                    <data>MagePal_PaymentFilterByProduct_Helper_Payment_Data</data>
                </rewrite>
            </payment>            
        </helpers>      
    </global>
</config>

In /app/code/local/MagePal/PaymentFilterByProduct/Helper/Payment/Data.php

<?php
class MagePal_PaymentFilterByProduct_Helper_Payment_Data extends Mage_Payment_Helper_Data
{

    public function getStoreMethods($store = null, $quote = null)
    {   
        $methods = parent::getStoreMethods($store, $quote);

        if(!Mage::getStoreConfig('paymentfilterbyproduct/general_option/paymentfilterbyproduct_enable', Mage::app()->getStore()) || !$quote){
            return $methods;
        }

        //get a list of product in cart
        $cart = Mage::getSingleton('checkout/session');

        $specialProductInCart = array();

        foreach ($cart->getQuote()->getAllItems() as $item) {
            $specialProductInCart[] = $item->getMagepalPaymentFilterByProduct();                 
        }

        // if special product in cart 
        // need to if check $item->getMagepalPaymentFilterByProduct() return 'yes/no' or '0/1)
        if(in_array('yes', $specialProductInCart)){
           $filter_csv = Mage::getStoreConfig('paymentfilterbyproduct/filter_option/paymentfilter_special_products', Mage::app()->getStore()); 
        }
        else{
            $filter_csv = Mage::getStoreConfig('paymentfilterbyproduct/filter_option/paymentfilter_all_product', Mage::app()->getStore());
        }

        $filter_array = explode(",", $filter_csv);

        foreach ($methods as $k => $method){
            if(!in_array($method->getCode(), $filter_array))
                unset($methods[$k]);       
        }//methods

        return $methods;
    }
}

In /app/code/local/MagePal/PaymentFilterByProduct/etc/system.xml

<?xml version="1.0"?>
<config>
    <tabs>
        <magepal translate="label" module="paymentfilterbyproduct">
            <label>MagePal</label>
            <sort_order>900</sort_order>
        </magepal>
    </tabs>
    <sections>
        <paymentfilterbyproduct translate="label" module="paymentfilterbyproduct">
            <label>Payment Method Filter by Product</label>
            <tab>magepal</tab>
            <sort_order>1000</sort_order>
            <show_in_default>1</show_in_default>
            <show_in_website>1</show_in_website>
            <show_in_store>1</show_in_store>
            <groups>
                <general_option translate="label">
                    <label>General Options</label>
                    <frontend_type>text</frontend_type>
                    <sort_order>1</sort_order>
                    <show_in_default>1</show_in_default>
                    <show_in_website>1</show_in_website>
                    <show_in_store>1</show_in_store>
                    <fields>
                        <paymentfilter_enable translate="label">
                            <label>Enable Payment Filter</label>
                            <frontend_type>select</frontend_type>
                            <source_model>adminhtml/system_config_source_yesno</source_model>
                            <sort_order>50</sort_order>
                            <show_in_default>1</show_in_default>
                            <show_in_website>1</show_in_website>
                            <show_in_store>1</show_in_store>
                        </paymentfilter_enable>
                    </fields>
                </general_option>
                <filter_option translate="label">
                    <label>Payment Method Filter Configuration</label>
                    <frontend_type>text</frontend_type>
                    <sort_order>2</sort_order>
                    <show_in_default>1</show_in_default>
                    <show_in_website>1</show_in_website>
                    <show_in_store>1</show_in_store>
                    <comment>Please enable all applicable payment methods in system payment config</comment>
                    <fields>
                        <paymentfilter_all_products translate="label">
                            <label>Select Default Payment option for All Products</label>
                            <frontend_type>multiselect</frontend_type>
                            <source_model>MagePal_PaymentFilterByProduct_ActivePaymentMethod</source_model>
                            <sort_order>30</sort_order>
                            <show_in_default>1</show_in_default>
                            <show_in_website>1</show_in_website>
                            <show_in_store>1</show_in_store>
                        </paymentfilter_admin>
                        <paymentfilter_special_products translate="label">
                            <label>Select Payments for Cart with Special Products</label>
                            <frontend_type>multiselect</frontend_type>
                            <source_model>MagePal_PaymentFilterByProduct_ActivePaymentMethod</source_model>
                            <sort_order>40</sort_order>
                            <show_in_default>1</show_in_default>
                            <show_in_website>1</show_in_website>
                            <show_in_store>1</show_in_store>
                        </paymentfilter_store>
                    </fields>
                </filter_option>
            </groups>
        </paymentfilterbyproduct>
    </sections>
</config>

In /app/code/local/MagePal/PaymentFilterByProduct/Helper/Data.php

<?php 
class MagePal_PaymentFilterByProduct_Helper_Data extends Mage_Core_Block_Template
{
}

In /app/code/local/MagePal/PaymentFilterByProduct/ActivePaymentMethod.php

<?php
class MagePal_PaymentFilterByProduct_ActivePaymentMethod
{
    //get all active (enable) payment method
    public function toOptionArray()
    {
       $payments = Mage::getSingleton('payment/config')->getActiveMethods();

       foreach ($payments as $paymentCode=>$paymentModel) {
           if($paymentModel->canUseCheckout() == 1){
                $paymentTitle = Mage::getStoreConfig('payment/'.$paymentCode.'/title');
                $methods[$paymentCode] = array(
                    'label'   => $paymentTitle,
                    'value' => $paymentCode,
                );
           }
        }

        return $methods;
    }
}

In /app/etc/modules/MagePal_PaymentFilterByProduct.xml

<?xml version="1.0"?>
<config>
    <modules>
        <MagePal_PaymentFilterByProduct>
            <active>true</active>
            <codePool>local</codePool>
        </MagePal_PaymentFilterByProduct>
    </modules>
</config>

Answer 2

An unobtrusive way of filtering payment method is to implement observer for event called payment_method_is_active

Steps
1> Register the event: ‘payment_method_is_active’ in config.xml. Add the following xml code in app/code/local/MagePsycho/Paymentfilter/etc/config.xml:

...
<global>
    ...
    <events>
        <payment_method_is_active>
            <observers>
                <paymentfilter_payment_method_is_active>
                    <type>singleton</type>
                    <class>paymentfilter/observer</class>
                    <method>paymentMethodIsActive</method>
                </paymentfilter_payment_method_is_active>
            </observers>
        </payment_method_is_active>
    </events>
    ...
</global>
...

2> Implement the observer model Create observer file: app/code/local/MagePsycho/Paymentfilter/Model/Observer.php and paste the following code:

<?php
/**
 * @category   MagePsycho
 * @package    MagePsycho_Paymentfilter
 * @author     magepsycho@gmail.com
 * @website    http://www.magepsycho.com
 * @license    http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
    */
class MagePsycho_Paymentfilter_Model_Observer {

    public function paymentMethodIsActive(Varien_Event_Observer $observer) {
        $event           = $observer->getEvent();
        $method          = $event->getMethodInstance();
        $result          = $event->getResult();
        $currencyCode    = Mage::app()->getStore()->getCurrentCurrencyCode();


            if($someTrueConditionGoesHere){
                $result->isAvailable = true;
            }else{
                $result->isAvailable = false;
            }

    }

}