Left join using LINQ

Question

Could someone give me an example of how to perform a left join operation using LINQ/lambda expressions?

Answer 1

well i tried to reproduce the famous left join where b key is null and the result i got is this extension method (with a little imagination you can modify it to just make a left join):

    public static class extends
{
    public static IEnumerable LefJoinBNull(this IEnumerable source, IEnumerable Target, Func key)
    {
        if (source == null)
            throw new ArgumentException("source is null");

        return from s in source
               join j in Target on key.Invoke(s) equals key.Invoke(j) into gg
               from i in gg.DefaultIfEmpty()
               where i == null
               select s;
    }
}