Magento change quote currency programmatically

Question

I am sending my magento store data to mobile application through soap request. I am having issue with multi currency. To mange the multi currency in android manging conversion through javascript.

My store support GBP , USD and Euro. Base currency is USD. Now when i switch currency to GBP in mobile it will convert the price correctly and send response to magento with my currency code and quote id for cart.

in request i am getting Quote Id and Currency code.

How can i set the GBP instead of the USD in quote?

i did try to set the currency using following code BUT it gets overwritten to USD not processing with GBP.

   $code=isset($_REQUEST['code'])?$_REQUEST['code']:'GBP';  

   $write_connection = Mage::getSingleton('core/resource')->getConnection('core_write'); 

   $fields_arr = array();

   $fields_arr['quote_currency_code'] = $code;     

   $where = $write_connection ->quoteInto('entity_id =?', $shoppingcartid); 
  $write_connection->update('sales_flat_quote', $fields_arr, $where);

Above code will set quote_currency_code currency in db for that quote id.

Need help to set the currency for quote programmatically.

Answer 1

You should use quote Model

$quote = Mage::getModel('sales/quote')->load($shoppingcartid);

Then Set Currency

$quote->setCurrency('GBP');