Linq to SQL - grouping products by the total quantity ordered

I'm trying to get a list of 'popular products' on an ecommerce site using LINQ to SQL - products are ordered and become rows in a Redemption table, with a quantity column to indicate the quantity ordered.

Here are the relevant bits of the tables:

Product

    ProductId INT
    ProductTitle VARCHAR
    (other columns not shown)

Redemption

    RedemptionId INT
    ProductId INT
    Quantity INT
    (other columns not shown)

I'm having t开发者_开发知识库rouble grouping and then ordering by the sum of quantity ordered. Here's what I have so far:

(from product in Products
join redemption in Redemptions on product.ProductId equals redemption.ProductId
group product by new { product.ProductId, product.ProductTitle } into g
orderby g.Sum(r => r.Key.Quantity) // Quantity is not part of the key :(
select g.Key).Take(5)

While I can group the products in the join to redemptions, I cannot order by the sum of quantities ordered.

Ideally, I only want the product object to be returned, not an anonymous type including the quantity.

Doing a join into makes it much easier:

var x = (from p in products
join r in redemptions on p.ProductId equals r.ProductId into pr
orderby pr.Sum(r => r.Quantity) descending
select p).Take(5);