c# Linq Object subQuery / In

Question

Hello, I have 2 objects that contains generic list properties. IE :

public class User
{
    public string Sid { get; set; }
    public List<Group> Groups { get; set; }
}

public class Section
{
    public string Sid { get; set; }
    public List<Group> Groups { get; set; }
}

From my BLL I get a generic list of sections List mySections=SectionDB.getList();

and my User object contains the user Information User myUser=UserDB.getInfo(sid);

Using linq to objects, is it possible to make a query that retreives all the sections where there is at least one group within the groups user class?

Any help?

Answer 1

from section in mySections
from sectionGroup in section.Groups
where myUser.Groups.Any(userGroup => userGroup == sectionGroup)
select section

i'd rather go for any, as you use the iterator much more efficiently

Answer 2

var sections = mySections.Where(x => x.Groups.Intersect(myUser.Groups)
    .Any()).ToList();

(note that this relies on either referential equality of the Group instances, or a suitable Equals / GetHashCode implementation on the Group type)