Hi all

It's the first time I'm using nHibernate in an ASP.NET project. We've got a Parent-Child relationship between 3 tables, let's call them parent, child1, child2.

In the parent class, I defined two bags for the one-to-many relationship (lazy=true), and the corresponding many-to-one mapping in the children. one of the children class has some properties that don't come directly from the child table, but from another inner-joined table:

(SQL)
SELECT
c.id, c.create_date, c.type_code,
t.type_description
FROM child c
inner join types t on (c.type_code = t.type_code)


So, I had to defined a <sql-query> to get the child data since a simple query.list(of child) cannot get the property type_description.

But the problem is, when I query the parent, nHibernate gets the data fine, but when I try to access the child list, I get an error for "lazy load exception", because nHibernate cannot find the corresponding "type_descripcion" field in the child table.

How do I tell nHibernate to use named query by default in a lazy-load of children?

Have you specified the query in the collection mapping ? Like (from reference doc, chapter 13.4):

thanx for your reply.

I've been playing with that <loader> tag, finally found out that I have to use session.Load() instead of session.CreateQuery() in order to have nHibernate use the named query to load the entity.

However, I have to use explicitly the session.Load() method to load the entity, but when I lazy load the child, it is done automatically by nHibernate, so, how can I tell nHibernate to "load" the child using the named query?

thanx

thanx for your reply.

I've been playing with that <loader> tag, finally found out that I have to use session.Load() instead of session.CreateQuery() in order to have nHibernate use the named query to load the entity.

However, I have to use explicitly the session.Load() method to load the entity, but when I lazy load the child, it is done automatically by nHibernate, so, how can I tell nHibernate to "load" the child using the named query?

thanx

Can you post your named query ?

Hi

here's my code:



<class name="Entities.Parent, Entities" table="PARENT" >
<id name="ParentId" column="PARENT_ID" type="System.Int32">
<generator class="assigned"/>
</id>
<property name="Name" column="NAME" access="field.camelcase-underscore"
not-null="false" type="System.String" insert="true" update="true"/>
<property name="ParentTypeCode" column="TYPE_CODE" access="field.camelcase-underscore"
not-null="false" type="System.String" insert="true" update="true"/>
<property name="ParentTypeName"
not-null="false" type="System.String" insert="false" update="false"/>
<bag name="Children" table="CHILD" cascade="all" lazy="true" inverse="true">
<key column="ParentId" />
<one-to-many class="Entities.Child, Entities" />
<loader query-ref="LoaderChild"/>
</bag>

<loader query-ref="LoaderParent"/>
</class>



<class name="Entities.Child, Entities" table="CHILD" >
<id name="ChildId" column="CHILD_ID" type="System.Int32">
<generator class="assigned"/>
</id>
<many-to-one name="Father" column="PARENT_ID" access="field.camelcase-underscore"
not-null="true" outer-join="auto"></many-to-one>
<property name="Name" column="NAME" access="field.camelcase-underscore"
not-null="false" type="System.String" insert="true" update="true"/>
<property name="ChildTypeCode" column="TYPE_CODE" access="field.camelcase-underscore"
not-null="false" type="System.String" insert="true" update="true"/>
<property name="ChildTypeName"
not-null="false" type="System.String" insert="false" update="false"/>

<loader query-ref="LoaderChild"/>
</class>




<sql-query name="LoaderParent">
<return alias="Parent" class="Entities.Parent, Entities" />
<![CDATA[
SELECT
p.PARENT_ID as {Parent.ParentId},
p.TYPE_CODE as {Parent.ParentTypeCode},
t.TYPE_NAME as {Parent.ParentTypeName},
FROM PARENT e
LEFT OUTER JOIN ENTITY_TYPE t ON (p.TYPE_CODE = t.CODE)
WHERE p.PARENT_ID = ?
]]>
</sql-query>


<sql-query name="LoaderChild">
<return alias="Child" class="Entities.Child, Entities" />
<![CDATA[
SELECT
c.PARENT_ID as {Child.ChildId},
c.TYPE_CODE as {Child.ChildTypeCode},
t.TYPE_NAME as {Child.ChileTypeName},
FROM CHILD c
LEFT OUTER JOIN ENTITY_TYPE t ON (c.TYPE_CODE = t.CODE)
WHERE c.PARENT_ID = ?
]]>
</sql-query>



Dim p1 As New Parent
p1 = sess.Load(GetType(Entities.Parent), parent_id)


When I execute the line, it loads the parent correctly, but when I try to access the children (Paren.Children), it tells me that it has a null reference

What's wrong with my code?

thank you very much

Akaik, you can't use the same query for entity and collection loading. For a collection query you need something like this:

It works!!!!

Thank you very much!!!!

:)