left outer join in lambda/method syntax in Linq [duplicate]

Answer 1

from p in Parent
join c in Child on p.PID equals c.PID into g
from c in g.DefaultIfEmpty()
select new 
{
   p.PID,
   CID = c != null ? (int?)c.CID : null, // Could be null
   Text = c != null ? c.Text : "[[Empty]]"
}

With lambda:

class ChildResult
{
   public int PID { get; set; }
   public int? CID { get; set; }
   public string Text { get; set; }
}

lParent.SelectMany(p => p.Childs.Any() ?
  p.Childs.Select(c => new ChildResult() { PID = c.PID, CID = c.CID, Text = c.Text }) :
  new [] { new ChildResult() { PID = p.PID, CID = null, Text = "[[Empty]]" } } );