Can you yield return into an IList<T>?

Question

In my service layer for my MVC application I am attempting to convert the linq to sql entity results into my business model entities. I am currently attempting the following code:

    public IList<Project> GetAllProjects()
    {
        var results = from p in _context.Repository<DBMappings.project>()
                      select p;

        foreach (DBMappings.project prj in results.ToList<DBMappings.project>())
            yield return CreateProjectEntityFromDBProject(prj);

    }

Unfortunately, this doesn't seem to work and the only thing I can guess is that yield only works with IEnumerable. Is there any other solution besides creating a new list, adding items in the foreach loop and returning the list? I need to use an IList because methods that use the returned list need to be able to do List Methods such as .Sort().

Answer 1

if you want to .Sort() you should definitely create a list in your method. using yield saves you some memory - because results are not stored as a single object. This is useful when you just want to walk over results. but if you want to Sort something you need it in memory as a single piece.