OR operator in XDocument.Descendants LINQ query

Question

I have a collection of XML files with two possible root node values but with the same structure and child elements. I loop through each of the files and build an object r of type Object that I then add to a new objects collection:

foreach (var file in files)
{
    var r = from x in file.Descendants("RootNode")
        select new Object
        {
            Field = ((string) x.Element("Field"))
        };
    objects.AddRange(r);
}

I want to do something like:

var r = from x in file.Descendants("RootNode") || file.Descendants("OtherRootNote") 

but can't figure out a logical way of doing this other than having two loops. Is that the only way?

Answer 1

You can use Descendants() to enumerate through all descendants, then add a standard where clause to filter those with the desired names:

            var r = from x in file.Descendants()
                    where x.Name == "RootNode" || x.Name == "OtherRootNode"
                    select new Object
                    {
                        Field = ((string)x.Element("Field"))
                    };

From the reference source, both overloads of Descendants() just do a linear walk through the element tree, so doing the name check yourself isn't computationally more complex.