Linq using Group by

I want to get the Category based total of the following

<?xml version="1.0" encoding="utf-8" ?> 
- <Data>
- <Products>
  <Product ProductId="1001" ProductName="p1" category="A1" 
  ProductPrice="123.45" /> 

  <Product ProductId="1002" ProductName="p2" category="B1"
   ProductPrice="100.45" /> 

  <Product ProductId="1003" ProductName="p3" category="A1"
   ProductPrice="223.45" /> 

  <Product ProductId="1004" ProductName="p4" category="B1"
   ProductPrice="200.45" /> 
  </Products>
....

What is the modification needed to achieve it in the following ?(nothing is returned in my query)

 XDocument doc = XDocument.Load("Product.xml");开发者_如何学编程

 var sum = from p in doc.Descendants("Product")
           group p by p.Attribute("Category") 
           into g
           select new { category = g.Key,
           total = g.Sum(p =>(double)p.Attribute("ProductPrice")) };

Your sample data shows an attribute of "category" but you're using "Category" in the query.

It looks like the query should nearly work other than that - although again I would strongly urge you to use decimal rather than double for the price.

EDIT: As Konamiman's now-deleted answer says, you need to group by the attribute value rather than the attribute itself. This code works (and uses decimal):

var sum = from p in doc.Descendants("Product")
          group p by p.Attribute("category").Value
          into g
          select new { category = g.Key,
                       total = g.Sum(p => (decimal) p.Attribute("ProductPrice"))
          };