Delete an item from many-to-many relationship - nhibernate

Question

I've following mapping for two tables having a Many-to-Many relationship between them. How do I delete an entry from the mapping table, which is 'TB_EMAIL_GRUPO_ARQUIVO' in my case? I just need to delete the data from this "joining" table and I don´t need to delete it from the "parent tables".
GrupoModulo
public GrupoModuloMap()
{
Schema(Const.SCHEMA);
Table(Const.TB_EMAIL_GRUPO_MODULO);
CompositeId()
.KeyReference(x => x.Grupo, Const.ID_GRUPO)
.KeyReference(x => x.Modulo, Const.ID_MODULO);
Map(x => x.GrupoId).Column(Const.ID_GRUPO).ReadOnly();
Map(x => x.ModuloId).Column(Const.ID_MODULO).ReadOnly();
HasManyToMany(x => x.Arquivos)
.Table(Const.TB_EMAIL_GRUPO_ARQUIVO)
.ParentKeyColumns.Add(Const.ID_GRUPO, Const.ID_MODULO)
.ChildKeyColumn(Const.ID_ARQUIVO)
.Cascade.SaveUpdate()
.Not.LazyLoad();
}
ArquivoRetorno
public ArquivoRetornoMap()
{
Schema(Const.SCHEMA);
Table(Const.TB_EMAIL_ARQUIVO_RETORNO);
Id(x => x.Id)
.Column(Const.ID_ARQUIVO)
.GeneratedBy.Sequence("SEQ_TB_EMAIL_ARQUIVO_RETORNO")
.Length(7).CustomSqlType("number(7)")
.Not.Nullable();
Map(x => x.Nome)
.Column("NM_ARQUIVO_RETORNO")
.Length(50)
.Not.Nullable();
References(x => x.Modulo)
.Column(Const.ID_MODULO)
.Not.Nullable();
HasManyToMany(x => x.GrupoModulos)
.Table(Const.TB_EMAIL_GRUPO_ARQUIVO)
.ChildKeyColumns.Add(Const.ID_GRUPO, Const.ID_MODULO)
.ParentKeyColumn(Const.ID_ARQUIVO)
.Cascade.SaveUpdate()
.Not.LazyLoad();
}
Whenever I try to delete I'm getting the following error:
deleted object would be re-saved by cascade (remove deleted object from associations)[Domain.Entity.GrupoModulo#Domain.Entity.GrupoModulo]
Someone has any idea?

Answer 1

The answer is (I am really sure) here: NHibernate Deleted object would be re-saved by cascade
Let me re-phrase that for your case, what could happen:
we remove an GrupoArquivo from ArquivoRetorno.GrupoModulos collection.
During that transaction, unit of work, we also tuch and therefore load the GrupoModulo
GrupoModulo gets initiated - and NOW - collection of Arquivos is loaded. So the reference to removed GrupoArquivo is kept there
NHibernate MUST inform: Deleted object would be re-saved by cascade
Solution(s):
be sure that the GrupoModulo is never loaded (stays as proxy)
or (the way I use) Remove() the GrupoArquivo also from GrupoModulo.Arquivos
or do NOT use CASCADE mapping on GrupoArquivo side:
(do not use the cascade)
HasManyToMany(x => x.Arquivos)
.Table(Const.TB_EMAIL_GRUPO_ARQUIVO)
.ParentKeyColumns.Add(Const.ID_GRUPO, Const.ID_MODULO)
.ChildKeyColumn(Const.ID_ARQUIVO)
//.Cascade.SaveUpdate()
// here
.Cascade.None()
.Not.LazyLoad();