EFCore BulkInsert with one to one relationship

Question

I'm trying to use bulkinsert from EFCore.BulkExtensions in .NET Core 2.1 with one to one relationships. I have 2 Database Entities

public partial class Entity1
{
    public int ID { get; set; }
    public virtual Entity2 Entity2Obj { get; set; }
}

public partial class Entity2 
{
    public int ID { get; set; }
    public int Entity1_ID{ get; set; }
    public virtual Entity1 Entity1Obj { get; set; }
}

Then I insert a list of Entity1 Items

 _context.BulkInsert(Entity1ItemsList);

This only works and inserts Entity1 objects in my database. The associated Entity2 items are not inserted. Is there a way to achieve that?

The navigation properties are automatically created during Scaffold-DbContext (database first)

entity.HasOne(d => d.Entity1 )
    .WithOne(p => p.Entity2)
    .HasForeignKey<Entity2>(d => d.Entity1_ID)
    .OnDelete(DeleteBehavior.ClientSetNull)
    .HasConstraintName("FK_Entity1_Entity2");

Answer 1

After searching around I think I found the solution. First of all set the following config

var bulkConfig = new BulkConfig()
{
    SetOutputIdentity = true,
    PreserveInsertOrder = true
};

Run the initial bulkconfig to insert the Entities1List and get the unique IDs from SQL Server

_context.BulkInsert(Entity1ItemsList, bulkConfig);

Now the unique primary keys are assigned so to set their values to their related entities use

foreach (var item in Entity1ItemsList)
{
    item.Entity2Obj.Entity1_ID = item.ID;
}

This will set the correct Foreign Key values. Then I BulkInsert the Entities2List

var Entities2List = Entity1ItemsList.Select(u => u.Entity2Obj).ToList();
 _context.BulkInsert(Entities2List);

I was hoping for something simpler by using only one BulkInsert which will automatically add all the navigation properties instead of 2. But this works and it's fast.

Answer 2

This is probably what you're looking for since you also want to insert child properties.

context.BulkInsert(Entity1ItemsList, options => options.IncludeGraph = true);

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