EF7 一对多映射

Question

I'm trying to map two classes using Entity Framework 7.0.0-rc1-final. Here's my classes:

    public class ParentClass
    {
            public ParentClass() { }

            [Key]
            public Int32 Id { get; set; }

            [Required]
            public String Field { get; set; }

            public List<ChildClass> Children { get; set; }

    }

    public class ChildClass
    {
        [Key]
        public Int32 Id { get; set; }

        public Int32 ParentID { get; set; }

        public ParentClass Parent { get; set; }
    }

and I have a mapping code in my context class with Fluent API:

    builder.Entity<ChildClass>().HasOne(x => x.Parent)
           .WithMany(x => x.Children).HasForeignKey(x => x.ParentID);

Then I add couple of ParentClass instances with children and save them to DB. They are saved to DB and look good in the DB, but when I'm trying to get list of ParentClass children I always have null list:

var data = _context.ParentInstances.ToList();
data[any].Children == null

Answer 1

You need to declare the fact that you want to include the children in query Try:

var data = _context.ParentInstances.Include(p => p.Children).ToList();

Edit:

For make sure to add a reference to Microsoft.Data.Entity