Entity-Framework – EF Core 2.0 – Cyclic Dependence, both ends need FK

public class User
{ 
 public int Id {get; set; }
 public string Name {get; set; }
 public int CurrentLocationId {get; set; }

 public List< Location> Locations {get; set; }
 public Location CurrentLocation {get; set; }
}

public class Location
{
 public int Id {get; set; }
 [Required]
 public int UserId {get; set; }
 public string Address {get; set; }

 public User User {get; set; }
}

builder.Entity()
 .HasOne(x => x.User)
 .WithMany(x => x.Locations)
 .HasForeignKey(x => x.UserId);

var location = new Location
{< br /> Address = "Some address"
};

_context.Locations.Add(location);

var user = new User
{ 
 Name = "Stu"
};

_context.Users.Add(user);

user.Locations = new List< br />{
 location
};

user.CurrentLocation = location;

await _context.SaveChangesAsync();

var location = new Location
{
 Address = "Some address"
};

var user = new User
{
 Name = "Stu",
 Locations = new List
 {
 location
 },
 CurrentLocation = location
};

_context.Users.Add(user); 
await _context.SaveChangesAsync();

I have a fairly simple data model that contains two entities:

public class User 
{
 public int Id {get; set; }
 public string Name {get; set; }
 public int CurrentLocationId {get; set; }

 public List Locations {get; set; }
 public Location CurrentLocation {get; set; }
}

and

public class Location
{
 public int Id {get; set; }
 [Required]
 public int UserId {get; set; }
 public string Address {get; set; }

 public User User {get; set; }
}

Then, in order to successfully run the migration, I need the following model builder Code:

builder.Entity()
 .HasOne(x => x.User)
 .WithMany(x => x. Locations)
 .HasForeignKey(x => x.UserId);

This produces a database that I expect and the way I need it. However, due to the following circular dependency error, I cannot Save entity:

InvalidOperationException: Unable to save changes because a circular dependency was detected in the data to be saved:’ForeignKey: User {‘CurrentLocationId’} -> Location {‘Id’} ToPrincipal: CurrentLocation, ForeignKey: Lo cation {‘UserId’} – >User{‘Id’} ToDependent: Location ToPrincipal: User’.

Is there a solution in EF Core 2.0?

I have some options to surround it by changing my data model, but this is the preferred method because I can use database constraints to ensure that all locations are linked back to the user, and each user must set CurrentLocation. I know it can solve the problem, but I can’t really allow null values ​​on the CurrentLocation field!

The code I used to try and store users is as follows (simplified for demonstration purposes):

var location = new Location
{< br /> Address = "Some address"
};

_context.Locations.Add(location);

var user = new User
{ 
 Name = "Stu"
};

_context.Users.Add(user);

user.Locations = new List< br />{
 location
};

user.CurrentLocation = location;

await _context.SaveChangesAsync();

And I tried it too

var location = new Location
{
 Address = "Some address"
};

var user = new User
{
 Name = "Stu",
 Locations = new List
 {
 location
 },
 CurrentLocation = location
};

_context.Users.Add(user); 
await _context.SaveChangesAsync();

But the error is still the same. Can this be fixed by some kind of fancy model builder override? Or am I restricting changes to my data model/allowing null values ​​I shouldn’t really allow null values?

Thanks in advance!

Answer my own question-I just checked, SQL server does not support deferrable constraints, so EF can’t do it anyway! Change to data model.