Getting error while Add to Cart programmatically with custom options - magento

Question

I am trying to Add Products to Cart with respect to customer (programmatically) but getting error "Invalid request for adding product to quote". I have both Simple products (with custom options) and configurable products. Below is my code. Please help. Many thanks in advance.
public function addtocartAction(){
try {
$cusId = $this->getRequest()->getParam('cusId');
$customer = Mage::getModel('customer/customer')->load($cusId);
$quote = Mage::getModel('sales/quote')->loadByCustomer($customer);
$quoteId = $quote->getId();
//$products = $this->getRequest()->getParam('products');
$products = json_decode('[{"proId": "906","proQty": "1", "options":{"17":"wq","16":"18"}}]');
foreach($products as $product) {
/*if (!$product->getId()) {
throw new Exception();
}*/
foreach ($product->options as $optKey => $optValue) {
$optAll[$optKey] = $optValue;
}
$mainProduct = Mage::getModel('catalog/product')->load($product->proId);
$params = array(
'product' => $product->proId,
'qty' => $product->proQty,
'options' => $optAll
);
echo "<pre />"; print_r($params);
$quote->addProduct($mainProduct, $params);
$quote->setIsActive(1);
$quote->collectTotals()->save();
}
$rslt['success'] = '1';
$rslt['message'] = 'Product has been succefully added to cart';
}
catch(Exception $e){
$rslt['success'] = '0';
$rslt['message'] = $e->getMessage();
}
print_r(json_encode($rslt));
}

Answer 1

Try using cart instead of quote.
This works for me:
$cart = Mage::getModel('checkout/cart');
$mainProduct = Mage::getModel('catalog/product')->load($product->proId);
$params = array(
'product' => $product->proId,
'qty' => $product->proQty,
'options' => $optAll
);
$cart->init();
$cart->addProduct($mainProduct, $params);
$cart->save();
Mage::getSingleton('checkout/session')->setCartWasUpdated(true);