Hello!

I am trying to fix the following problem for hours now, so maybe you can help me getting it work:

All I want to do is to load some data from two joined tables into objects. Searching the web lead me to the code below, but it does not work correctly! There

are no compilation errors, but the number af children is never correct.


The goal is to access the children objects by parent.children(number).

What happens is that NHibernate creates an outer join which leads to dublicated primary key entries in my parent object list and thus a wrong number of

childs of every parent entry.

Perhaps this is easier to understand the problem:
If I use a bag than the outer join deliveres one row per child, also including the parent-id. But NHibernate does not map this correctly to my objects.

If I use a set it returns the correct number of parents but a too small number of childs.

Another thing I have tried was to use an inverse end by defining a <key-to-many... in the children class which causes a stack overflow when using
fetch="join" and works while using fetch="select".


By the way: What is the main difference between bag and set?

Thanks for any advice.

Regards
Stefan

How are you actually loading the objects? Can you please post the code?

Hello Sergey,

thanks for having a look at our problem. Its bugging us really hard ;)

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This is the database structure:
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This is the object structure:
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These are the XML-Config-Files:
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Content of Person.hbm.xml:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0" default-access="property">
<class name="AppCore.Person, AppCore" table="T_PERSON">
<id name="ID" column="ID" access="nosetter.pascalcase-underscore">
<generator class="native" />
</id>
<property name="Name" column="Name" access="nosetter.pascalcase-underscore"/>
<property name="Alter" column="[Alter]" access="nosetter.pascalcase-underscore"/>

<bag fetch="join" name="Adressen" cascade="all" access="nosetter.pascalcase-underscore" lazy="true" inverse="true">
<key column="PersonID" />
<one-to-many class="AppCore.Adresse, AppCore" />
</bag>
</class>
</hibernate-mapping>

Content of Adresse.hbm.xml:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0" default-access="property">
<class name="AppCore.Adresse, AppCore" table="T_ADRESSE">
<id name="ID" column="ID" access="nosetter.pascalcase-underscore">
<generator class="native" />
</id>
<property name="StrasseHausnummer" column="StrHNr" access="nosetter.pascalcase-underscore"/>
<property name="PLZ" column="PLZ" access="nosetter.pascalcase-underscore"/>
<property name="Ort" column="Ort" access="nosetter.pascalcase-underscore"/>


<many-to-one name="Person" column="PersonID" class="AppCore.Person, AppCore" cascade="none" />

</class>
</hibernate-mapping>

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This is the code:
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Public Sub TestNHibernate()
Dim nhConfig As New NHibernate.Cfg.Configuration

nhConfig.AddClass(GetType(AppCore.Person))
nhConfig.AddClass(GetType(AppCore.Adresse))

Dim SessionFactory As ISessionFactory = nhConfig.BuildSessionFactory()
Dim NSession As ISession = SessionFactory.OpenSession()

' clear Person table
NSession.Delete("FROM Person")
NSession.Flush()

Dim Query As ICriteria = NSession.CreateCriteria(GetType(AppCore.Person)).Add(Expression.Like("Name", "John", NHibernate.Expression.MatchMode.Anywhere))

Dim Personen As IList = Query.List


'If no person exists (because it is deleted above) create some dummy data
If Personen.Count = 0 Then
Dim JWayne As New AppCore.Person
JWayne.Alter = 22
JWayne.Name = "John Wayne"

'Add a first child element
Dim HeimAdresse As New AppCore.Adresse()
HeimAdresse.Person = JWayne
HeimAdresse.StrasseHausnummer = "Burgstr. 4"
HeimAdresse.Ort = "Frankfurt"
HeimAdresse.PLZ = "52134"

JWayne.Adressen.Add(HeimAdresse)

'Add a second child element
Dim FirmenAdresse As New AppCore.Adresse()
FirmenAdresse.Person = JWayne
FirmenAdresse.StrasseHausnummer = "Karl-Friedrich-Str. 74"
FirmenAdresse.Ort = "Cologne"
FirmenAdresse.PLZ = "12345"

JWayne.Adressen.Add(FirmenAdresse)

NSession.Save(JWayne)
NSession.Flush()
End If


Query = NSession.CreateCriteria(GetType(AppCore.Person)).Add(Expression.Like("Name", "Frank", NHibernate.Expression.MatchMode.Start))

'Add a second person
If Query.List.Count = 0 Then
Dim Frank As New AppCore.Person
Frank.Alter = 22
Frank.Name = "Frank Warren"

'Add a first child element
Dim HeimAdresse As New AppCore.Adresse()
HeimAdresse.Person = Frank
HeimAdresse.StrasseHausnummer = "Mittelstra