I have the following object associations.

Project
ProjectClass (bi-directional many-to-many to Project)
WellProjectClass (subclass of ProjectClass)
GeologicalPrognosis (bidirectional association to WellProjectClass)

I want to develop an hql query that will return me the
GeologicalPrognosis instance based on the id of the Project class.

I have tried a few times, but I'm not sure how I can reference the subclass (WellProjectClass) through a join of the Project object.

Some examples here would be appreciated. Thanks..

Mapping files to follow:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0"
assembly="WellAccelerator.Domain" namespace="WellAccelerator.Domain"
>

<class name="Project" table="PROJECT">

<id name="ProjectId" column="PROJECT_ID" type="Int64" unsaved-value="0">
<generator class="native"/>
</id>
<property name="ProjectName" column="PROJECT_NAME"/>

<many-to-one name="ProjectType" column="PROJECT_TYPE_ID" class="ProjectType" />

<bag name="ProjectClasses" table="PROJECT_CLASS_XREF" cascade="all" outer-join="true">
<key column="PROJECT_ID" />
<many-to-many column="PROJECT_CLASS_ID"
class="WellAccelerator.Domain.ProjectClass, WellAccelerator.Domain" />
</bag>

<many-to-one name="Strike" column="Strike_Id" class="Strike"/>
<many-to-one name="Jurisdiction" column="Jurisdiction_Id"
class="Jurisdiction"/>

</class>

</hibernate-mapping>

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0"
assembly="WellAccelerator.Domain" namespace="WellAccelerator.Domain"
>

<class name="ProjectClass" table="PROJECT_CLASS" discriminator-value="PC">

<id name="ProjectClassId" column="PROJECT_CLASS_ID" type="Int64" unsaved-value="0">
<generator class="native"/>
</id>

<discriminator column="CLASS_CODE" type="String" length="4"/>

<bag name="Projects" table="PROJECT_CLASS_XREF" inverse="true" cascade="all" outer-join="true">
<key column="PROJECT_ID" />
<many-to-many column="PROJECT_CLASS_ID"
class="WellAccelerator.Domain.Project, WellAccelerator.Domain" />
</bag>

<bag name="Locations" table="PROJECT_CLASS_LOCATION" cascade="all" outer-join="true">
<key column="LOCATION_ID" />
<many-to-many column="PROJECT_CLASS_ID"
class="WellAccelerator.Domain.Location, WellAccelerator.Domain" />
</bag>

<property column="PROJECT_CLASS_TYPE"
type="WellAccelerator.Domain.ProjectClassCode, WellAccelerator.Domain"
name="ProjectClassCode" not-null="true"
/>

<many-to-one name="ProjectAfe" class="ProjectAfe" column="ProjectAfeId"/>
<property name="WorkingInterest" column="WorkingInterest"/>
<many-to-one name="Product" column="ProductId" class="Product"/>
<many-to-one name="OperatingTeam" column="OperatingTeamId" class="OperatingTeam"/>

</class>
</hibernate-mapping>


<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0"
assembly="WellAccelerator.Domain" namespace="WellAccelerator.Domain"
>

<subclass name="WellProjectClass" extends="ProjectClass" discriminator-value="WELL">
<one-to-one class="GeologicalPrognosis" name="GeologicalPrognosis" cascade="all"/>
</subclass>
</hibernate-mapping>


<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0"
assembly="WellAccelerator.Domain" namespace="WellAccelerator.Domain"
>

<class name="GeologicalPrognosis" table="PROGNOSIS" discriminator-value="0">

<id name="Id" column="PROGNOSIS_ID" type="Int64">
<generator class="foreign">
<param name="property">WellProjectClass</param>
</generator>
</id>

<one-to-one class="WellProjectClass" name="WellProjectClass" constrained="true"/>
<many-to-one class="PrognosisStatus" name="PrognosisStatus" />
<property column="Ground_Elevation" name="GroundElevation" not-null="false"/>
<property column="Kb_Elevation" name="KbElevation" not-null="false"/>
<property column="Metres_Penetrated" name="MetresPenetrated" not-null="false"/>
<property column="sample_requirements" name="SampleRequirements" not-null="false"/>
<property column="tight_hole" name="TightHole" not-null="false"/>
<property column="off_target" name="OffTarget" />
<property column="total_measured_depth" name="TotalMeasuredDepth"/>
<many-to-one class="ConfidentialStatus" name="ConfidentialStatus"/>
<property column="dpt_exploratory_depth" name="DptExploratoryDepth"/>
<property column="comments" name="PrognosisComments"/>

</class>
</hibernate-mapping>[/b]

try something like this:

HTH,
radu

Thanks Radu,

I did try this:



Thanks for the example.

I think the only difference is that I concatenated the value of the id instead of using a paramater as your example. Not sure if that would make a difference. I haven't seen an example of passing in a parameter such as you have done. I'll check the documentation.

My query returns no results. It should have returned a single instance of the GeologicalPrognosis class.

I think I missed sending one of my mapping files. This is the parent to WellProjectClass. Not sure if it would make a difference to how the hql is written.:

you should check what happens by doing tests with the generated SQL.

To use params:

IQuery query=session.CreateQuery(....
query.SetInt32("id",projectId);

the first param is the name of the param used in the query, the second one is the value assigned to it.

cheers,
Radu

Thanks for the tips. I'll use that approach in the future while I'm learning NHibernate. I did discover an error in my mapping files which accounted for not having returned the expected row. I have fixed it and it is now working properly.

Thanks for the helpful tips.