Entity Framework making incorrect PK-FK mapping on Code First migration - ef-code-first

Question

I have the following 3 classes set up to be created in a SQL Server database using Entity Framework Code First migrations. The Survey object is the main table.
public class Survey
{
public int SurveyId {get; set;} //Primary Key
public string Description {get; set;}
public bool HasDevice {get; set;}
public bool HasProcess {get; set;}
public virtual Process Process {get; set;}
public virtual ICollection<Device> Devices {get; set;}
}
Each Survey can have multiple Devices (1-to-many)
public class Device
{
public int DeviceId {get; set;} //Primary Key
public string DeviceType {get; set;}
public int SurveyId {get; set;} //Foreign Key
public virtual Survey Survey {get; set;}
}
Each Survey should have only one Process (1-to-0..1)
public class Process
{
public int ProcessId {get; set;} //Primary Key
public string ProcessInfo {get; set;}
public int SurveyId {get; set;} //Foreign Key
public virtual Survey Survey {get; set;}
}
The Fluent API mapping for these classes looks like this.
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.HasDefaultSchema("Survey");
modelBuilder.Entity<Survey>().HasOptional(x => x.Process).WithRequired(x => x.Survey);
modelBuilder.Entity<Survey>().HasMany(x => x.Devices).WithRequired(x => x.Survey);
}
The problem is that when I apply the code first migration, the ForeignKey property in the Process table (1-to-0..1) keeps getting set to the ProcessId field rather than the SurveyId. This means that every time I try to add a new Process record, I get the following error:
The INSERT statement conflicted with the FOREIGN KEY constraint "FK_Survey.Processes_Survey.Surveys_ProcessId". The conflict occurred in database "Backflow", table "Survey.Surveys", column 'SurveyId'.
The 1-to-many mapping for Device works just fine.
I thought initially that this was due to having all my PK fields just say Id, but even after adding in the additional label part, it still makes the incorrect PK-FK link. I have also tried avoiding the Fluent API by adding the DataAnnotation [Key, ForeignKey("xyz")] instead but it has the same result. Recompiling the project, restarting Visual Studio, and even creating a new project and a new database do not help.
Is there something in the Fluent API or DataAnnotations that I am missing to get this to join correctly? Also, manually fixing the FK in the database does make it work, but that kind of defeats the purpose of doing everything in Code First with migrations.

Answer 1

The fluent mapping of the 1-0..1 relationship is correct:
modelBuilder.Entity<Survey>()
.HasOptional(s => s.Process)
.WithRequired(p => p.Survey);
But Process shouldn't have a SurveyID property (and column). In EF6, the dependent part of a 1-0..1 relationship (here: Process) is supposed to have a primary key that also refers to its principal (here: Survey) as foreign key. So Process.ProcessID is both primary key and foreign key. Thus, one Process is uniquely tied to one Survey.
By the way, in the other mapping, I would also mention the foreign key: if configuration is chosen over convention, it better be complete.
modelBuilder.Entity<Survey>()
.HasMany(s => s.Devices)
.WithRequired(d => d.Survey)
.HasForeignKey(d => d.SurveyId);