User input product dimensions, update price based on inputs now Working!

Hello!

This will be my first and probably the only contribution I will do on this forum, since my job doesn't allow me to distribute code\solutions provided by us, and since this is just a Patch, I will share it with you:

Zahid Hussain shared the code that worked:
"you want to edit this file: includes/classes/shopping_cart.php"

Find the following code (should be around line 1243):

        $products_array[] = array('id' => $products_id, 
                                  'category' => $products->fields['master_categories_id'], 
                                  'name' => $products->fields['products_name'], 
                                  'model' => $products->fields['products_model'], 
                                  'image' => $products->fields['products_image'], 
                                  'price' => ($products->fields['product_is_free'] =='1' ? 0 : $products_price), 
        //                                    'quantity' => $this->contents[$products_id]['qty'], 
                                  'quantity' => $new_qty, 
                                  'weight' => $products->fields['products_weight'] + $this->attributes_weight($products_id), 
                                  // fix here 
                                  'final_price' => ($products_price + $this->attributes_price($products_id)), 
                                  'onetime_charges' => ($this->attributes_price_onetime_charges($products_id, $new_qty)), 
                                  'tax_class_id' => $products->fields['products_tax_class_id'], 
                                  'attributes' => (isset($this->contents[$products_id]['attributes']) ? $this->contents[$products_id]['attributes'] : ''), 
                                  'attributes_values' => (isset($this->contents[$products_id]['attributes_values']) ? $this->contents[$products_id]['attributes_values'] : ''), 
                                  'products_priced_by_attribute' => $products->fields['products_priced_by_attribute'], 
                                  'product_is_free' => $products->fields['product_is_free'], 
                                  'products_discount_type' => $products->fields['products_discount_type'], 
                                  'products_discount_type_from' => $products->fields['products_discount_type_from']); 
      } 
    } 
    $this->notify('NOTIFIER_CART_GET_PRODUCTS_END'); 
    return $products_array; 
  }  

And REPLACE with this:

        //begin Attribute Calculator 1.0 
        //Zen Cart contribution by JT Website Design http://www.jtwebsitedesign.com     
        $description_sql = 'SELECT products_name FROM ' . TABLE_PRODUCTS_DESCRIPTION . ' where products_id = "' . (int) $products_id . '"'; 

        $pdescription = $db->Execute($description_sql); 
        $products_name = $pdescription->fields['products_name']; 

        switch($products->fields['products_name']) 
            { 
              case 'Product A': 
              $priceFactor = 1.00; 
              break; 
              case 'Product B': 
              $priceFactor = 0.50; 
              break; 
              case 'Product C': 
              $priceFactor = 1.25; 
              break; 
              default: 
            $priceFactor = 0;         
            } 
        if($priceFactor != 0) 
            { 
            $Length_ID_Query = "select products_options_id from " . TABLE_PRODUCTS_OPTIONS . " where products_options_name = 'Length'"; 
            $Length_ID = $db->Execute($Length_ID_Query); 
            $LengthID = (int)$Length_ID->fields['products_options_id']; 
     
            $Width_ID_Query = "select products_options_id from " . TABLE_PRODUCTS_OPTIONS . " where products_options_name = 'Width'"; 
            $Width_ID = $db->Execute($Width_ID_Query); 
            $WidthID = (int)$Width_ID->fields['products_options_id']; 
             
            if ($this->contents[$products_id]['attributes_values'][$WidthID] && $this->contents[$products_id]['attributes_values'][$LengthID]) 
            $areaFactor = $this->contents[$products_id]['attributes_values'][$WidthID]*$this->contents[$products_id]['attributes_values'][$LengthID]; 
             
            else 
            $areaFactor = 0; 
            $extraCharge = $areaFactor * $priceFactor; 
            } 
        else 
            $extraCharge = 0; 
        //end Attribute Calculator 1.0 

        $products_array[] = array('id' => $products_id, 
                                  'category' => $products->fields['master_categories_id'], 
                                  'name' => $products->fields['products_name'], 
                                  'model' => $products->fields['products_model'], 
                                  'image' => $products->fields['products_image'], 
                                  'price' => ($products->fields['product_is_free'] =='1' ? 0 : $products_price+$extraCharge), 
        //                                    'quantity' => $this->contents[$products_id]['qty'], 
                                  'quantity' => $new_qty, 
                                  'weight' => $products->fields['products_weight'] + $this->attributes_weight($products_id), 
                                  // fix here 
                                  'final_price' => ($products_price + $this->attributes_price($products_id) + $extraCharge), 
                                  'onetime_charges' => ($this->attributes_price_onetime_charges($products_id, $new_qty)), 
                                  'tax_class_id' => $products->fields['products_tax_class_id'], 
                                  'attributes' => (isset($this->contents[$products_id]['attributes']) ? $this->contents[$products_id]['attributes'] : ''), 
                                  'attributes_values' => (isset($this->contents[$products_id]['attributes_values']) ? $this->contents[$products_id]['attributes_values'] : ''), 
                                  'products_priced_by_attribute' => $products->fields['products_priced_by_attribute'], 
                                  'product_is_free' => $products->fields['product_is_free'], 
                                  'products_discount_type' => $products->fields['products_discount_type'], 
                                  'products_discount_type_from' => $products->fields['products_discount_type_from']); 
      } 
    } 
    $this->notify('NOTIFIER_CART_GET_PRODUCTS_END'); 
    return $products_array; 
  }  

The thing is that that code was delivering the base price + the price by Area;

All I had to do was to replace

$extraCharge = $areaFactor * $priceFactor

by

 $extraCharge = $areaFactor * $priceFactor-$products_price; 

Not that so far this is the only free sollution working on an open-source e-commerce platform, thanks a lot to the creator and have fun coding.