Seeding tables with one to many relationship EF code first - entity-framework

Question

I'm trying to seed some database tables that have a one to many relationship. Using the code first approach with the Entity Framework. Somehow the foreign keys remain empty in the database table activities, column UserId.
Why isn't this working?
context.Users.AddOrUpdate(
u => u.FirstName,
new User { Id = 1, FirstName = "Trees", Preposition = "de", LastName = "Vries", EmailAddress = "trees#test.com", PhoneNumber = 0684637485, Password = "test123", RoleId = 1 }
);
context.SaveChanges();
context.Activities.AddOrUpdate(
a => a.Name,
new Activity
{
Name = "Metselen van de binnenplaats",
Comment = "Voorbeeld commentaar regel 1.",
Start = DateTime.Now,
End = DateTime.Now.AddHours(5),
},//etc.
);
context.SaveChanges();
var randomActivities = (from s in context.Activities select s).OrderBy(x => Guid.NewGuid()).Take(6).ToList();
context.Users.AddOrUpdate(
u => u.Id,
new User { Id = 1, Activities = randomActivities }
);
context.SaveChanges();
Edit: Solution
After a few hours of wrestling with the code I finally managed to get it all working (without having to add foreign keys to the model classes).
I will share the code and some discoveries so others might benefit from it.
A few things to keep in mind.
Code directly to the context!
This does not work:
List<Activity> randomActivities = (from s in context.Activities select s).OrderBy(x => Guid.NewGuid()).Take(2).ToList(); //Does not work
Works:
List<Activity> randomActivities = context.Activities.OrderBy(x => Guid.NewGuid()).Take(2).ToList();
Only call SaveChanges() when you need to link objects that already need to be in the tables.
context.SaveChanges();
And Finally, you can create the data with a relationship to other tables, simple by adding a new List into it (see code below for details).
The seed method looks like this now:
var users = new List<User>
{
new User
{
FirstName = "Trees",
Preposition = "de",
LastName = "Vries",
EmailAddress = "trees#test.com",
PhoneNumber = 0684637485,
Password = "test123",
Activities =
new List<Activity> { // <-- Like this!
new Activity { Name = "Boren muren in de grote hal 1", Start = DateTime.Now, End = DateTime.Now.AddHours(5) },
new Activity { Name = "Vloer schuren 1", Start = DateTime.Now, End = DateTime.Now.AddHours(1) },
new Activity { Name = "Boren muren in de grote hal 2", Start = DateTime.Now, End = DateTime.Now.AddHours(5) },
new Activity { Name = "Vloer schuren 2", Start = DateTime.Now, End = DateTime.Now.AddHours(1) }
},
Messages =
new List<Message>
{
new Message { Subject = "Test onderwerp van bericht 1", Body = "Tekst van het bericht 1", AuthorId = 3 },
new Message { Subject = "Test onderwerp van bericht 2", Body = "Tekst van het bericht 2", AuthorId = 3 },
new Message { Subject = "Test onderwerp van bericht 3", Body = "Tekst van het bericht 3", AuthorId = 3 }
}
},
new User { FirstName = "Jaap", LastName = "Winter", EmailAddress = "jaap#test.com", PhoneNumber = 0628305643, Password = "test123" },
new User { FirstName = "Klaas", LastName = "Janssen", EmailAddress = "klaas#test.com", PhoneNumber = 0639453321, Password = "test123" }
};
users.ForEach(s => context.Users.AddOrUpdate(r => r.FirstName, s));
context.SaveChanges();
List<Activity> randomActivities = context.Activities.OrderBy(x => Guid.NewGuid()).Take(2).ToList();
var projects = new List<Project>
{
new Project { Name = "Test project", Description = "Omschrijving van test project 1.", Start = DateTime.Now, End = DateTime.Now.AddDays(10), User = context.Users.Single(s => s.FirstName == "Trees"), Activities = randomActivities }
};
projects.ForEach(s => context.Projects.AddOrUpdate(r => r.Name, s));
Activity model class:
public class Activity
{
public int Id { get; set; }
public string Name { get; set; }
public DateTime Start { get; set; }
public DateTime End { get; set; }
public Skill Skill { get; set; }
public string Comment { get; set; }
}
User model class:
public int Id { get; set; }
public string FirstName { get; set; }
public string Preposition { get; set; }
public string LastName { get; set; }
public string EmailAddress { get; set; }
public int PhoneNumber { get; set; }
public string Password { get; set; }
public bool Active { get; set; }
public Role Role { get; set; }
public ICollection<Skill> Skills { get; set; }
public ICollection<Message> Messages { get; set; }
public ICollection<Activity> Activities { get; set; }
}