Fatal eror in cart page and blank view page

Question

I need solution for this : Changing price is not reflecting for configurable products so as suggested by @Arjen Miedema,

I followed : Magento Configurable Product Price Overriding Simple Product Price

1)when i used only git hub extension referred by @Pronto= > worked fine in view page, but not in cart page.

2)when i used only @Alan answer = > worked fine in cart page, but not in view page.

than i override the price.php of an extension using @Alan answer, than in cart page i saw following error

Fatal error: Call to a member function getFinalPrice() on a non-object in 
app/code/core/Mage/Cata‌​log/Model/Product.php on line 717

this is line 717 : return $this->getPriceModel()->getFinalPrice($qty, $this);

and view page is showing blank now.

I am using following code in

Price.php

app/code/community/OrganicInternet/SimpleConfigurableProducts/Catalog/Model/Product/Type/Configurable/Price.php

<?php
/**
 * Magento
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Open Software License (OSL 3.0)
 * that is bundled with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://opensource.org/licenses/osl-3.0.php
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to [email protected] so we can send you a copy immediately.
 *
 * DISCLAIMER
 *
 * Do not edit or add to this file if you wish to upgrade Magento to newer
 * versions in the future. If you wish to customize Magento for your
 * needs please refer to http://www.magentocommerce.com for more information.
 *
 * @category    Mage
 * @package     Mage_Catalog
 * @copyright   Copyright (c) 2014 Magento Inc. (http://www.magentocommerce.com)
 * @license     http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
 */

/**
 * Product type price model
 *
 * @category    Mage
 * @package     Mage_Catalog
 * @author      Magento Core Team <[email protected]>
 */
class Mage_Catalog_Model_Product_Type_Configurable_Price extends Mage_Catalog_Model_Product_Type_Price
{
    /**
     * Get product final price
     *
     * @param   double $qty
     * @param   Mage_Catalog_Model_Product $product
     * @return  double
     */
    public function getFinalPrice($qty=null, $product)
    {
        if (is_null($qty) && !is_null($product->getCalculatedFinalPrice())) {
            return $product->getCalculatedFinalPrice();
        }

        $basePrice = $this->getBasePrice($product, $qty);
        $finalPrice = $basePrice;
        $product->setFinalPrice($finalPrice);
        Mage::dispatchEvent('catalog_product_get_final_price', array('product' => $product, 'qty' => $qty));
        $finalPrice = $product->getData('final_price');

        $finalPrice += $this->getTotalConfigurableItemsPrice($product, $finalPrice);
        $finalPrice += $this->_applyOptionsPrice($product, $qty, $basePrice) - $basePrice;
        $finalPrice = max(0, $finalPrice);

        $product->setFinalPrice($finalPrice);
        return $finalPrice;
    }

    /**
     * Get Total price for configurable items
     *
     * @param Mage_Catalog_Model_Product $product
     * @param float $finalPrice
     * @return float
     */
    public function getTotalConfigurableItemsPrice($product, $finalPrice)
    {
        $price = 0.0;

        $product->getTypeInstance(true)
                ->setStoreFilter($product->getStore(), $product);
        $attributes = $product->getTypeInstance(true)
                ->getConfigurableAttributes($product);

        $selectedAttributes = array();
        if ($product->getCustomOption('attributes')) {
            $selectedAttributes = unserialize($product->getCustomOption('attributes')->getValue());
        }

        foreach ($attributes as $attribute) {
            $attributeId = $attribute->getProductAttribute()->getId();
            $value = $this->_getValueByIndex(
                $attribute->getPrices() ? $attribute->getPrices() : array(),
                isset($selectedAttributes[$attributeId]) ? $selectedAttributes[$attributeId] : null
            );
            $product->setParentId(true);
            if ($value) {
                if ($value['pricing_value'] != 0) {
                    $product->setConfigurablePrice($this->_calcSelectionPrice($value, $finalPrice));
                    Mage::dispatchEvent(
                        'catalog_product_type_configurable_price',
                        array('product' => $product)
                    );
                    $price += $product->getConfigurablePrice();
                }
            }
        }
        return $price;
    }

    /**
     * Calculate configurable product selection price
     *
     * @param   array $priceInfo
     * @param   decimal $productPrice
     * @return  decimal
     */
    protected function _calcSelectionPrice($priceInfo, $productPrice)
    {
        if($priceInfo['is_percent']) {
            $ratio = $priceInfo['pricing_value']/100;
            $price = $productPrice * $ratio;
        } else {
            $price = $priceInfo['pricing_value'];
        }
        return $price;
    }

    protected function _getValueByIndex($values, $index) {
        foreach ($values as $value) {
            if($value['value_index'] == $index) {
                return $value;
            }
        }
        return false;
    }
}

please help me where i am missing now?

Answer 1

<?php

#The methods in there have become a bit convoluted, so it could benefit from a tidy,
#...though the logic is not that simple any more.

class OrganicInternet_SimpleConfigurableProducts_Catalog_Model_Product_Type_Configurable_Price
    extends Mage_Catalog_Model_Product_Type_Configurable_Price
{
    #We don't want to show a separate 'minimal' price for configurable products.
    public function getMinimalPrice($product)
    {
        return $this->getPrice($product);
    }

    public function getMaxPossibleFinalPrice($product) {
        #Indexer calculates max_price, so if this value's been loaded, use it
        $price = $product->getMaxPrice();
        if ($price !== null) {
            return $price;
        }

        $childProduct = $this->getChildProductWithHighestPrice($product, "finalPrice");
        #If there aren't any salable child products we return the highest price
        #of all child products, including any ones not currently salable.

        if (!$childProduct) {
            $childProduct = $this->getChildProductWithHighestPrice($product, "finalPrice", false);
        }

        if ($childProduct) {
            return $childProduct->getFinalPrice();
        }
        return false;
    }

    #If there aren't any salable child products we return the lowest price
    #of all child products, including any ones not currently salable.
   public function getFinalPrice($qty=null, $product)
{
    //Start edit
    $selectedAttributes = array();
    if ($product->getCustomOption('attributes')) {
        $selectedAttributes = unserialize($product->getCustomOption('attributes')->getValue());
    }
    //End edit
    if (sizeof($selectedAttributes)) return $this->getSimpleProductPrice($qty, $product);

    if (is_null($qty) && !is_null($product->getCalculatedFinalPrice())) {
        return $product->getCalculatedFinalPrice();
    }

    $basePrice = $this->getBasePrice($product, $qty);
    $finalPrice = $basePrice;
    $product->setFinalPrice($finalPrice);
    Mage::dispatchEvent('catalog_product_get_final_price', array('product' => $product, 'qty' => $qty));
    $finalPrice = $product->getData('final_price');

    $finalPrice += $this->getTotalConfigurableItemsPrice($product, $finalPrice);
    $finalPrice += $this->_applyOptionsPrice($product, $qty, $basePrice) - $basePrice;
    $finalPrice = max(0, $finalPrice);

    $product->setFinalPrice($finalPrice);
    return $finalPrice;
}



    public function getPrice($product)
    {
        #Just return indexed_price, if it's been fetched already
        #(which it will have been for collections, but not on product page)
        $price = $product->getIndexedPrice();
        if ($price !== null) {
            return $price;
        }

        $childProduct = $this->getChildProductWithLowestPrice($product, "finalPrice");
        #If there aren't any salable child products we return the lowest price
        #of all child products, including any ones not currently salable.
        if (!$childProduct) {
            $childProduct = $this->getChildProductWithLowestPrice($product, "finalPrice", false);
        }

        if ($childProduct) {
            return $childProduct->getPrice();
        }

        return false;
    }

    public function getChildProducts($product, $checkSalable=true)
    {
        static $childrenCache = array();
        $cacheKey = $product->getId() . ':' . $checkSalable;

        if (isset($childrenCache[$cacheKey])) {
            return $childrenCache[$cacheKey];
        }

        $childProducts = $product->getTypeInstance(true)->getUsedProductCollection($product);
        $childProducts->addAttributeToSelect(array('price', 'special_price', 'status', 'special_from_date', 'special_to_date'));

        if ($checkSalable) {
            $salableChildProducts = array();
            foreach($childProducts as $childProduct) {
                if($childProduct->isSalable()) {
                    $salableChildProducts[] = $childProduct;
                }
            }
            $childProducts = $salableChildProducts;
        }

        $childrenCache[$cacheKey] = $childProducts;
        return $childProducts;
    }

/*
    public function getLowestChildPrice($product, $priceType, $checkSalable=true)
    {
        $childProduct = $this->getChildProductWithLowestPrice($product, $priceType, $checkSalable);
        if ($childProduct) {
            if ($priceType == "finalPrice") {
                $childPrice = $childProduct->getFinalPrice();
            } else {
                $childPrice = $childProduct->getPrice();
            }
        } else {
            $childPrice = false;
        }
        return $childPrice;
    }
*/
    #Could no doubt add highest/lowest as param to save 2 near-identical functions
    public function getChildProductWithHighestPrice($product, $priceType, $checkSalable=true)
    {
        $childProducts = $this->getChildProducts($product, $checkSalable);
        if (count($childProducts) == 0) { #If config product has no children
            return false;
        }
        $maxPrice = 0;
        $maxProd = false;
        foreach($childProducts as $childProduct) {
            if ($priceType == "finalPrice") {
                $thisPrice = $childProduct->getFinalPrice();
            } else {
                $thisPrice = $childProduct->getPrice();
            }
            if($thisPrice > $maxPrice) {
                $maxPrice = $thisPrice;
                $maxProd = $childProduct;
            }
        }
        return $maxProd;
    }

    public function getChildProductWithLowestPrice($product, $priceType, $checkSalable=true)
    {
        $childProducts = $this->getChildProducts($product, $checkSalable);
        if (count($childProducts) == 0) { #If config product has no children
            return false;
        }
        $minPrice = PHP_INT_MAX;
        $minProd = false;
        foreach($childProducts as $childProduct) {
            if ($priceType == "finalPrice") {
                $thisPrice = $childProduct->getFinalPrice();
            } else {
                $thisPrice = $childProduct->getPrice();
            }
            if($thisPrice < $minPrice) {
                $minPrice = $thisPrice;
                $minProd = $childProduct;
            }
        }
        return $minProd;
    }

    //Force tier pricing to be empty for configurable products:
    public function getTierPrice($qty=null, $product)
    {
        return array();
    }
}

Answer 2

/home/outthinking/public_html/upload/em0113-full-package/app/code/core/Mage/Cata‌​log/Model/Product.php

Please check which line you have fatal error, this fatal error means that you call a method of a null object.