Question

I was trying to do a join and then a group by, My grouped information that is returned is great! works like a charm, but i still need access to values outside the grouping, if that makes sense..

I found an example on stackoverflow, which probably explains it better

var query = from c in context.Contacts
            join o in context.Orders on c.Id equals o.CustomerId
            select new 
            { 
                Contact = c, 
                Order = o 
            } into ContactAndOrder
            group ContactAndOrder by ContactAndOrder.Order.Id into g
            select new 
            { 
                g.Key, 
                ContactWhatever = g.Sum(co => co.Contact.Whatever), 
                OrderWhatever = g.Sum(co => co.Order.Whatever) 
            };

Now this seems to work great, problem is in my situation the co.Order.Whatever is a string so i get an error saying can’t convert string to int, this i understand as the aggregate function Sum expects a int….

My question really is, is there an aggregate function or something similar to i can get the value of co.Order.Whatever (a string in my case )

The problem being is once the group by has been done i lose “c” and “o”

I hope someone can help.

thanks in advance

Answer 1

if it’s always the same in the group, the First will be enough…

ContactWhatever = g.First().Contact.Whatever

else use @Andrei Answer
or

ContactWhatever = g.Select(o => o.Contact.Whatever).Aggregate((a,b) => a + "," + b)