What is the LINQ query to get a Cartesian Product even when one set is EMPTY?

Question

Imagine I have 2 list and one is empty:

List<string> foo = new List<string>(){ "Ali","wall-e","Ellie" };
List<string> bar = new List<string>();

And I obtain the Cartesian Product of 2:

var q = from f in foo
    from b in bar
    select new {f,b};

As bar is empty LINQ returns an empty result set.

Question: How can I write the above query so that I can receive this result set:

Ali,NULL

Wall-e,NULL

Ellie,NULL

Answer 1

Maybe this is what you want:

var q = from f in foo.DefaultIfEmpty()
    from b in bar.DefaultIfEmpty()
    select new {f,b};