Question

I am using EF 4.1 Code First and I am having trouble initializing my data the way I think I should be able to. In my code below, you will see that I have a model that starts with Client and it contains a series of related objects. I load each object type and set it into its parent. After my data is loaded into my objects, i try to save the top level object Client to the database. When I do this I get a System.NullReferenceException.

Will EF not do deep loading?

Do I need to save each object set to the database first them relate them to eachother a resave them to the database? If I have to do this, it seem like it would be a lot of conections to load my data when it should be able to be performed in one query.

Any advice or answrs would be appreciated.

Below is my code, and below that is my exception:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.Entity;

namespace MyNameSpace
{
  class Program
  {
    static void Main(string[] args)
    {
        Database.SetInitializer(new TimeServiceContextInitializer());
        TimeServiceContext db = new TimeServiceContext();
        var clients = db.Clients.ToList();

        foreach (var client in clients)
        {
            Console.WriteLine("Client: {0}\r\nNumber of Sites: {1}\r\n", client.Name, client.Sites.Count);  
        }
    }
}

// Initialize Database
public class TimeServiceContextInitializer : DropCreateDatabaseIfModelChanges<TimeServiceContext>
{
    protected override void Seed(TimeServiceContext db)
    {
        List<Client> clients = new List<Client>();

        Client client = new Client();
        client.Name = "Achme Big Company";

        Site site = new Site();
        site.Name = "www.SampleSite.com";

        Project project = new Project();
        project.Name = "Schololarship Application Phase 1";
        project.Description = "Create an application that allows student to apply for scholarship in the www.SampleSite.com web site.";
        project.DateCreated = DateTime.Now.AddDays(-15);
        project.StartDate = DateTime.Now.AddDays(-5);
        project.DeadlineDate = DateTime.Now.AddDays(45);
        project.Status = Status.In_Progress;
        project.FixedFee = 40500.00m;
        project.SpecialNotes = "This project has a firm deadline due to the fact that marketing information is already set to go out to advertize applying for scholarships online through the web site";

        TimeEntry timeEntry = new TimeEntry();
        timeEntry.EmployeeName = "Brian Johns";
        timeEntry.TasksPerformed = "Started working on sceen mockups for the first page of the scholoarship application";
        timeEntry.TimeRecorded = DateTime.Now.AddDays(-4).AddHours(10);
        project.TimeEntries.Add(timeEntry); /// <---- --------------------------- GET System.NullReferenceException Exception Here -----------

        timeEntry = new TimeEntry();
        timeEntry.EmployeeName = "Brian Johns";
        timeEntry.TasksPerformed = "Completed first section of form fields and started on the second section for the first page of the scholoarship application";
        timeEntry.TimeRecorded = DateTime.Now.AddDays(-4).AddHours(11.5);
        project.TimeEntries.Add(timeEntry);

        timeEntry = new TimeEntry();
        timeEntry.EmployeeName = "Brian Johns";
        timeEntry.TasksPerformed = "Decided we needed to regroup fields so started modifying form layout to work better on the first page of the scholoarship application";
        timeEntry.TimeRecorded = DateTime.Now.AddDays(-4).AddHours(13.25);
        project.TimeEntries.Add(timeEntry);

        timeEntry = new TimeEntry();
        timeEntry.EmployeeName = "Brian Johns";
        timeEntry.TasksPerformed = "Completed first form of the scholarship application.  Started discussing the next form for step 2 of the scholarship application process";
        timeEntry.TimeRecorded = DateTime.Now.AddDays(-4).AddHours(14);
        project.TimeEntries.Add(timeEntry);

        site.Projects.Add(project);
        client.Sites.Add(site);

        db.Clients.Add(client);
        db.SaveChanges();

        base.Seed(db);
    }
}

// Context
public class TimeServiceContext : DbContext
{
    public DbSet<Client> Clients { get; set; }
    public DbSet<Site> Sites { get; set; }
    public DbSet<Project> Projects { get; set; }
    public DbSet<TimeEntry> TimeEntries { get; set; }
}

// Model Starts Here
public class Client
{
    public int Id { get; set; }
    public string Name { get; set; }
    public ICollection<Site> Sites { get; set; }
    public DateTime DateCreated { get; set; }
}

public class Site
{
    public int Id { get; set; }
    public string Name { get; set; }
    public ICollection<Project> Projects { get; set; }
    public int ClientId { get; set; }
    public DateTime DateCreated { get; set; }
}

public enum Status { Not_Started, In_Progress, Completed };

public class Project
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public DateTime StartDate { get; set; }
    public DateTime DeadlineDate { get; set; }
    public DateTime CompletionDate { get; set; }
    public decimal FixedFee { get; set; }
    public decimal HourlyRate { get; set; }
    public Status Status { get; set; }
    public string SpecialNotes { get; set; }

    public ICollection<TimeEntry> TimeEntries { get; set; }
    public int SiteId { get; set; }
    public DateTime DateCreated { get; set; }
}

public class TimeEntry
{
    public int id { get; set; }
    public string EmployeeName { get; set; }
    public string TasksPerformed { get; set; }
    public DateTime TimeRecorded { get; set; }
    public int InvoiceNumber { get; set; }
    public int ProjectId { get; set; }
}
}

Esception Details:
System.NullReferenceException was unhandled by user code
Message=Object reference not set to an instance of an object.
Source=Console
StackTrace:
at MyNameSpace.TimeServiceContextInitializer.Seed(TimeServiceContext db) in C:\Users\Justin\Source Control\CoutoTimeService\Console\Program.cs:line 51
at System.Data.Entity.DropCreateDatabaseIfModelChanges1.InitializeDatabase(TContext context)
at System.Data.Entity.Database.<>c__DisplayClass21.b_0(DbContext c)
at System.Data.Entity.Internal.InternalContext.<>c_DisplayClass5.b_3()
at System.Data.Entity.Internal.InternalContext.PerformInitializationAction(Action action)
at System.Data.Entity.Internal.InternalContext.PerformDatabaseInitialization()
at System.Data.Entity.Internal.LazyInternalContext.b_4(InternalContext c)
at System.Data.Entity.Internal.RetryAction`1.PerformAction(TInput input)
InnerException:

Answer 1

add a constructor to your project class

Project(){
TimeEntries = new HashSet<TimeEntry>();
}

you can also make your code a bit pretier with object initializers like this:

Project project = new Project(){
    Name = "Schololarship Application Phase 1",
    Description = "Create an application that allows student to apply for scholarship in the www.SampleSite.com web site.",
    DateCreated = DateTime.Now.AddDays(-15),
    StartDate = DateTime.Now.AddDays(-5),
    DeadlineDate = DateTime.Now.AddDays(45),
    Status = Status.In_Progress,
    FixedFee = 40500.00m,
    SpecialNotes = "This project has a firm deadline due to the fact that marketing information is already set to go out to advertize applying for scholarships online through the web site"
};