Perform Inner Join on 2 Files of type IEnumerable<XElement>

Question

Lets say I have 2 files of type IEnumerable<XElement>. How would I perform an inner join and/or a group join on them? I have tried the following but the .Join method does not work on IEnumerable's. Any help would be appreciated.

var innerjoin = file1.Join(file2, c => file1.Elements("OrderID"), o => file2.Elements("OrderID"), (c, o) => new { Customer = c, Order = o });

Answer 1

Assuming that file1 and file2 contains IEnumerable<XElement> where each XElement has a child element OrderID, you can do join by OrderID value like this :

var innerjoin = file1.Join(file2, 
                            c => (string)c.Element("OrderID"), 
                            o => (string)o.Element("OrderID"),
                            (c, o) => new {Customer = c, Order = o});

Or using the equivalent query syntax :

var innerjoin = from c in file1
                join o in file2 
                   on (string)c.Element("OrderID") equals (string)o.Element("OrderID")
                select new {Customer = c, Order = o};