Entity Framework 6 Code One: How to seed data using "circular" relationships and store-generated columns?

I am new to EF Code First and I am trying to seed my database with some data using code first migrations. So far I've managed to solve a few errors, but now I'm stuck and couldn't find an answer. I have two problems while updating the database from my code.

I have several objects that have different many-to-many and one-to-one relationships, and some end up creating a circle. I'm not sure if this is the reason for the second problem or not when I try to seed the database.

• First error: A dependent property in a ReferentialConstraint is mapped to a store-generated column. Column: 'LicenseId'.
  
  

Is there a way to use the db generated id as a foreign key? Is it just the order in which I create / insert objects? (see seeding code below)

If I do not use [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]

in the License, I get an error that I am unable to implicitly insert an identifier that is not generated by the database.

public class License : Entity
{
    [Key, ForeignKey("Customer")]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int LicenseId { get; set; }

    [Required(ErrorMessage = "Date Created name is required")]
    public DateTime DateCreated { get; set; }

    public virtual ICollection<ProductLicense> ProductLicenses { get; set; } // one License has many ProductLicenses
    public virtual Customer Customer { get; set; } // one Customer has one License
}

public class Customer : Entity
{
    [Key]
    public int CustomerId { get; set;}

    [Required(ErrorMessage = "Username is required")]
    [Column(TypeName = "nvarchar")]
    [MaxLength(500)]
    public string Name { get; set; }

    public virtual ICollection<User> Users { get; set; } // one Customer has many users
    public virtual License License { get; set; } // one Customer has one License
    //public virtual ICollection<License> License { get; set; } // one Customer has many Licenses
}

      

        
        
        
      

    

2. If I change License-Customer to be a many-to-many relationship (which I don't want), I get the following error: Cannot insert duplicate key row in object 'dbo.Users' with unique index 'IX_Username'.
   
   

This is all my relationship:

Customer -many-> User -many-> Role -many-> Permission -one- ProductLicense <-many- License -one- Customer

      

        
        
        
      

    

Here is the code I used in protected override void Seed(DAL.Models.Context context)

creating objects in code and then using AddOrUpdate:

// Default Customers - create
var customers = new[]{
    new Customer { Name = "cust_a" },
    new Customer { Name = "cust_b" },
    new Customer { Name = "cust_c" }
};

// Default Licenses - create
var licenses = new[]{
    new License { DateCreated = DateTime.Now.AddDays(-3), Customer = customers[0] },
    new License { DateCreated = DateTime.Now.AddDays(-2), Customer = customers[1] },
    new License { DateCreated = DateTime.Now.AddDays(-1), Customer = customers[2] }
};

// Default ProductLicenses - create, and add default licenses
var productLicenses = new[]{
    new ProductLicense { LicenceType = LicenseType.Annual, StartDate = DateTime.Now, License = licenses[0] },
    new ProductLicense { LicenceType = LicenseType.Monthly, StartDate = DateTime.Now, License = licenses[1] },
    new ProductLicense { LicenceType = LicenseType.PAYG, StartDate = DateTime.Now, License = licenses[2] }
    };

// Default Permissions - create, and add default product licenses
var permissions = new[]{
    new Permission { Name = "Super_a", ProductLicense = productLicenses[0] },
    new Permission { Name = "Access_b", ProductLicense = productLicenses[1] },
    new Permission { Name = "Access_c", ProductLicense = productLicenses[2] }
};

// Default Roles - create, and add default permissions
var roles = new[]{
    new Role { Name = "Super_a", Permissions = permissions.Where(x => x.Name.Contains("_a")).ToList() },
    new Role { Name = "User_b", Permissions = permissions.Where(x => x.Name.Contains("_b")).ToList() },
    new Role { Name = "User_c", Permissions = permissions.Where(x => x.Name.Contains("_c")).ToList() }
};

// Default Users - create, and add default roles
var users = new[]{
    new User { Username = "user@_a.com", Password = GenerateDefaultPasswordHash(), Salt = _defaultSalt, Roles = roles.Where(x => x.Name.Contains("_a")).ToList() },
    new User { Username = "user@_b.co.uk", Password = GenerateDefaultPasswordHash(), Salt = _defaultSalt, Roles = roles.Where(x => x.Name.Contains("_b")).ToList() },
    new User { Username = "user@_c.com", Password = GenerateDefaultPasswordHash(), Salt = _defaultSalt, Roles = roles.Where(x => x.Name.Contains("_c")).ToList() }
        };

// Default Customers - insert, with default users

foreach (var c in customers)
{
    c.Users = users.Where(x => x.Username.Contains(c.Name.ToLower())).ToList();
    context.Customers.AddOrUpdate(c);
}

      

        
        
        
      

    

I also tried changing the first part after //Default Customers - create

to

// Default Customers - create and insert
context.Customers.AddOrUpdate(
    u => u.Name,
    new Customer { Name = "C6" },
    new Customer { Name = "RAC" },
    new Customer { Name = "HSBC" }
);

context.SaveChanges();

var customers = context.Customers.ToList();

      

        
        
        
      

    

I would really appreciate help on this so that I can seed my database with the appropriate data.

Thanks a lot for your help and sorry for the long post.

--- UPDATE ---

After following Chris Pratt's excellent answer below, I get the following error: Conflicting changes detected. This may happen when trying to insert multiple entities with the same key.

Here is my new code for seeding and all models used: https://gist.github.com/jacquibo/c19deb492ec3fff0b5a7

Can anyone help with this?