In JPA, having a many-to-one as primary key throws referential integrity constraint violation -

i have defined following entities:

@entity public class child implements serializable {     @id    @manytoone(cascade = cascadetype.all)    public parent parent;     @id    public int id; }  @entity public class parent {    @id    public int id; } 

when try persist child following code:

parent p = new parent(); p.id = 1;  child c1 = new child(); c1.id = 1; c1.parent = p;  em.persist(c1); 

hibernate throws 'referential integrity constraint violation' error:

caused by: org.h2.jdbc.jdbcsqlexception: referential integrity constraint violation: "fk3e104fc802aac0a: public.child foreign key(parent_id) references public.parent(id) (1)"; sql statement: insert child (parent_id, id) values (?, ?) [23506-171] 

i believe because first inserts child , parent, while expect insert parent first. idea how can change order of insertion, or how to solve in other way?

update: note approach not jpa compliant, uses hibernate specifics (see section 5.1.2.1. composite identifier in hibernate docs)

update: have persist child c1 , have persist cascade parent p automatically (this update in reaction @alf's answer below).

em.persist(p); em.persist(c1); 

update

i think problem code not jpa compliant. try embeddedid, works me.

@embeddable public class childpk implements serializable {     private int parentid;      private int childid;      // getters , setters }  @entity public class child implements serializable {     @embeddedid     public childpk id = new childpk();      @mapsid( "parentid" )     @manytoone     public parent parent;  }       parent p = new parent();     p.id = 1;      child c1 = new child();     c1.id.setchildid( 1 );      c1.parent = p;      em.persist( c1 ); 

i think works @idclass too, never used it.