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Hibernate version:1.0.2

Mapping documents:
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="Competition.Business2.Forums.Post, Competition.Business2" table="t_forum_posts">
<id name="ID" column="PostID" type="int" unsaved-value="0">
<generator class="native" />
</id>

<property name="AddedDate" not-null="false" />
<many-to-one name="AddedBy" column="AddedBy"/>
<property name="AddedByIP" not-null="false" />
<many-to-one name="Forum" column="ForumID" not-null="false"/>
<many-to-one name="ParentPost" column="ParentPostID" not-null="false"/>
<property name="Title" not-null="false" />
<property name="Body" not-null="false" />
<property name="Approved" not-null="false" />
<property name="Closed" not-null="false" />
<property name="ViewCount" not-null="false" />
<property name="ReplyCount" not-null="false" />
<many-to-one name="LastPostBy" column="LastPostBy" not-null="false"/>
<property name="LastPostDate" not-null="false" />

</class>
</hibernate-mapping>


Good day everyone,

I've been using NHib for a little while now and I've always played around an issue I've been having since the beginning for which I cannot find a solution in the documentation. It is probably in there somewhere and my apologies if it is obvious, but I'm writing to the forum as a last resort.

So, first problem: in the previous mapping I want to make the LastPostBy and ParentPost property optional (namely nullable). The database schema allow for nulls in those fields. How do I do that? I thought that not-null would do the trick, but not. When saving the object I get a 'Value cannot be null' error (and the only null parameter is LastPostBy).

Second question: can a many-to-one parameter can be made to load lazily?

Thanks in advance for enlighting me,
Alain-Daniel

The not-null attribute only affects the DDL generated by hbm2ddl, not any NH behavior. Something else seems to be going on here, since <many-to-one> should be able to handle null references automatically--it simply sets the FK to NULL, no problem. I've implemented a simple tree like that before, so I know the ParentPost should be working.

Maybe the issue is with LastPostBy. What is the mapping/class for that?

Thank you for your help marcal.

I made a mistake with the database schema and the problem was indeed with LastPostBy and I've fix the problem.

I would still like to know if I can make a many-to-one load lazily, if there are any taker to answer it :-)

Alain-Daniel

No, but the object itself should load lazily unless it is marked otherwise.

Which is to say: rather than hydrating an object when the many-to-one property is called, a proxy object will be referenced by the property, and the data will be retreived when a property on the proxy is called.