Question

I have two tables, for Users and Songs. I need to JOIN them both on the UserID column and return a list to the view. I tried writing an anonymous type but I’m getting an error about:

‘Only parameterless constructors and initializers are supported in LINQ to Entities.’

How can I JOIN and return to list?

 public class User
    {
        [Key]
        public virtual Guid UserId { get; set; }

        [Required]
        public virtual String Username { get; set; }

        [Required]
        public virtual String Email { get; set; }

        [Required, DataType(DataType.Password)]
        public virtual String Password { get; set; }

}





 public class Song
    {
        public int SongId { get; set; }

        public virtual Guid UserId { get; set; }

        public string SongTitle { get; set; }

    }

I tried implementing a method like this one here:

What is the return type of my linq query?

The query I ended up with was:

var query = from u in db.Users
                        join s in db.Songs
                        on u.UserId equals s.UserId
                        select new HomeSongList(s.SongId, s.UserId, u.Username);


            return View(query.ToList());

Answer 1

You can’t use parameterized constructors but you can use initializers, if you change your select to the following it should work.

select new HomeSongList{SongId=s.SongId, UserId=s.UserId, Username=u.Username};

Note that this will require that HomeSongList has a parameterless constructor and writable properties.