c# - Entity Framework Core: How to add a composite object? -

there following composite object, example:

public class parent {     [key]     public int id { get; set; }      [foreignkey("childrefid")]     public guid childid { get; set; }      public child child { get; set; } }  public class child {     [key]     public guid id { get; set; }      [foreignkey("parentrefid")]     public int parentid { get; set; }      public parent parent { get; set; } } 

parent , child has one-to-one relation:

modelbuilder.entity<parent>()     .hasone(parent => parent.child)     .withone(child => child.parent)     .willcascadeondelete(); 

i try create new parent child , save in db:

var parent = new parent { child = new child() }; dbcontext.parents.add(parent); dbcontext.savechanges(); //<-- exception! 

...and following exception:

system.data.sqlclient.sqlexception: insert statement conflicted foreign key constraint "fk_parent_child_childid". conflict occurred in database "mydatabase", table "dbo.child", column 'id'. 

if use db context create child works fine:

var child = dbcontext.childs.add(new child()); var parent = new parent { child = child }; dbcontext.parents.add(parent); dbcontext.savechanges(); //<-- works fine 

question #1: can add new entities nested collections without using context create it. not works one-to-one relation. example:

var parent = new parent(); parent.grandparents.add(new grandparent(); dbcontext.parents.add(parent); dbcontext.savechanges(); //<-- works fine , parent 1 new grandparent created! 

why?

question #2: please, describe me wrong , how can save new parent child without context create child (like nested collections)?

thank you!

this error occurring beta-8 version of ef. after updated ef rc1-final version error disappeared. may explained there no graph tracking on beta-8 version yet.

you can find more detailed information here.