HQL: Querying dynamic-component property

Question

If I have a mapping like this:

<class name="Library" table="Libraries">
  ...
  <dynamic-component name="Annotations">
    <property name="LibraryResolver.AlgorithmVersion" column="`LibraryResolver.AlgorithmVersion`" type="Int32" />
  </dynamic-component>
</class>

How should I write HQL or Linq-to-NHibernate query for all libraries where LibraryResolver.AlgorithmVersion is greater than a given value?

Answer 1

I don't know whether this helps but when I use the Criteria API (in Java) it just works. Haven't tried with HQL though.

<dynamic-component name="values">
        <property name="dynamicNameValue" column="ATTRIBUTE_1" type="string"/>
        <property name="dynamicNumber" column="ATTRIBUTE_4" type="integer"/>
</dynamic-component>

Criteria criteria = session.createCriteria(DynamicAttributes.class)
                .add(Expression.eq("values.dynamicNumber", 2));

Just some thought: could it be that the problem is that the name ('LibraryResolver.AlgorithmVersion') you're passing contains a dot? Maybe post some code you already attempted?

Answer 2

The HQL query below maybe along the lines you are looking for

from Library as lib
where lib.Annotations.LibraryResolver.AlgorithmVersion > 2

If you're using nhibernate, have you tried out the NHibernate LambdaExtensions? This library provides a set of extensions methods over the Criteria and DetachedCriteria apis which removes the need of magic strings when querying using the above two api.

Below is an example of how one might use NHibernate Detached Criteria query with the mentioned LambdaExtensions library

Answer answerAlias = null;
var actual = DetachedCriteria.For<Survey>()
.Add<Survey>( s => s.Status == SurveyStatus.Complete )
.Add<Questionnaire>( q => q.Id == questionnaireId )
.CreateAlias<Survey>( s => s.Answers, () => answerAlias )
.SetProjection( LambdaProjection.Property( () => answerAlias.Id ) );