Linq-to-Entities Left JOIN

Question

This is my query:

from forum in Forums
    join post in Posts on forum equals post.Forum into postGroup    

    from p in postGroup     
    where p.ParentP         


        

Answer 1

Try something like this:

from forum in Forums 
join post in Posts on forum equals post.Forum into postGroup     

// from p in postGroup      
// where p.ParentPostID==0 

select new  
{ 
    forum.Title, 
    forum.ForumID,   
    LastPostTitle = postGroup.FirstOrDefault(p => p.ParentPostID==0).Title, 
    LastPostAddedDate = (DateTime?)postGroup.FirstOrDefault(p => p.ParentPostID==0).AddedDate          
}).OrderBy(o=>o.ForumID)

properties that return empty from the left join must also be nullable. So int => int? and DateTime => DateTime? etc..