Ok,
I spent more hours with the problem and now I am quite sure it is a bug, or I am doing something totaly wrong. I realized that problem is not when managing asociation in constructor, but from anywhere. The problem occure after adding new child into parent, if the bidirectional many-to-one association is lazy and was not loaded from the database before saving the child. I im posting some clear code without any specific lines, classes code and mappings.
Here is the code just for preparing data, I need to create a parent with one child to test:
Code:
...CreateSession();
Parent par = new Parent();
Child chd = new Child();
chd.Name = "First one";
chd.Parent = par;
par.Childrens.Add(chd);
...CurrentSession.Save(par);
Debug.WriteLine(...CurrentSession.GetIdentifier(par)); // output is "5"
...CurrentSession.Transaction.Commit();
Now, here is the code that works fine, it is because I load lazy collection using "Debug.WriteLine(par.Childrens.Count);":
Code:
...CreateSession();
Parent par = (Parent)...CurrentSession.Load(typeof(Parent), 5);
Debug.WriteLine(par.Childrens.Count); // output is "1"
Child chd = new Child();
chd.Name = "Second one";
chd.Parent = par;
par.Childrens.Add(chd);
Debug.WriteLine(par.Childrens.Count); // output is "2"
...CurrentSession.Save(chd); // I need to know the identifier, so I must save object
int i = (int)...CurrentSession.GetIdentifier(chd); // I know the identifier
Debug.WriteLine(par.Childrens.Count); // output is "2"
...CurrentSession.Transaction.Rollback();
And finally, the code which works in a bad way. I rollbacked all changes made by previous code, my database contains only one parent with one child before running the code. After adding new child to existing parent and after saving the new child, it is existing twice in the bag collection. The output of the "par.Childrens.Count" should be "2", not "3".Code:
...CreateSession();
Parent par = (Parent)...CurrentSession.Load(typeof(Parent), 5);
Child chd = new Child();
chd.Name = "Second one";
chd.Parent = par;
par.Childrens.Add(chd);
...CurrentSession.Save(chd);
int i = (int)...CurrentSession.GetIdentifier(chd);
Debug.WriteLine(par.Childrens.Count); // output is "3"
...CurrentSession.Transaction.Rollback();
The last code just to show that everything works fine if the collection is loaded before save:
Code:
Parent par = (Parent)...CurrentSession.Load(typeof(Parent), 5);
Child chd = new Child();
chd.Name = "Second one";
chd.Parent = par;
par.Childrens.Add(chd);
Debug.WriteLine(par.Childrens.Count); // output is "2"
...CurrentSession.Save(chd);
int i = (int)...CurrentSession.GetIdentifier(chd);
Debug.WriteLine(par.Childrens.Count); // output is "2"
The code of the classes:
Code:
using System;
using System.Collections;
namespace TEST.Business.Subjects {
public class Parent {
private int m_Id;
private IList m_Childrens = new ArrayList();
public virtual int Id {
get { return m_Id; }
}
public virtual IList Childrens {
get { return m_Childrens; }
}
}
public class Child {
private int m_Id;
private string m_Name;
private Parent m_Parent;
public virtual int Id {
get { return m_Id; }
}
public virtual string Name {
get { return m_Name; }
set { m_Name = value; }
}
public virtual Parent Parent {
get { return m_Parent; }
set { m_Parent = value; }
}
}
}
And the mapping file:
Code:
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping
xmlns="urn:nhibernate-mapping-2.0"
default-access="field.pascalcase-m-underscore"
assembly="TEST.Business.Subjects"
namespace="TEST.Business.Subjects"
>
<class name="TEST.Business.Subjects.Parent" table="Parent" lazy="true">
<id name="Id" type="Int32" column="id_Parent" unsaved-value="0" access="nosetter.pascalcase-m-underscore">
<generator class="native" />
</id>
<bag name="Childrens" inverse="true" cascade="save-update" lazy="true">
<key column="id_Parent" />
<one-to-many class="TEST.Business.Subjects.Child" />
</bag>
</class>
<class name="TEST.Business.Subjects.Child" table="Child" lazy="true">
<id name="Id" type="Int32" column="id_Child" unsaved-value="0" access="nosetter.pascalcase-m-underscore">
<generator class="native" />
</id>
<many-to-one name="Parent" class="TEST.Business.Subjects.Parent" column="id_Parent" not-null="true" />
<property name="Name" type="String" not-null="true" />
</class>
</hibernate-mapping>
Please can someone help me?
Many thanks. David
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