c# - NHibernate Deleted object would be re-saved by cascade

Question

In my solution I have a branch of business objects with associations. So when I try save a root object after processing I get an exception with message "Deleted object would be re-saved by cascade". What means that after deleting of an object its still exists in collections, other association and so on. Does somebody knows how to get a list of references to the deleted object. Its very difficult to find references without debugger support.

Answer 1

The most common scenario (my experience) is having two root objects having collections of some pairing/middle object.

public class Employee 
{
    public virtual IList<Occupation> Occupations { get; set; }
}
public class Company
{
    public virtual IList<Occupation> Occupations { get; set; }
}

Now, we have the Occupation like this

public class Occupation
{
    public virtual Employee Employee { get; set; }
    public virtual Company  Company  { get; set; }
}

So, what could happen:

1. we remove an Occupation from employee.Occupations collection.
2. During that transaction, unit of work, we also tuch and therefore load the Company
3. Company gets initiated. Its collection of Occupations get loaded. So the reference to removed Occupation is kept there
4. NHibernate says: Deleted object would be re-saved by cascade

Solution(s):

• be sure that the Company is never loaded (stays as proxy)
• or Remove() the Occupation also from company.Occupations
• do not use mapping like this on Company side:

(do not use the cascade)

<bag name="Occupations" lazy="true" inverse="true" batch-size="25" 
     cascade="all-delete-orphan">
     // this above setting on Company side is making issues...
  <key column="Company_ID" />
  <one-to-many class="Occupation" />
</bag>