R – Fluent nhibernate table-per-hierarchy mapping

fluent-nhibernatenhibernate-mapping

I have a simple scenario where I have an entity Action (this is a workflow style application) that has a DueDate calculated property.

Now id like to introduce a SlidingAction, whose only difference (at this stage) is to override the DueDate calculation, as such has none of its own mapping.

Im having difficulty mapping this scenario since Fluent Nhibernate seems to be forcing me to map 'something' on the subclass.

Could someone shed some light?

Cheers,
Byron

public class ActionMap : ClassMap<Action>
{
    public ActionMap()
    {
        WithTable("Actions");
        Id(x => x.ID);
        Map(x => x.Description);
        Map(x => x.TimeLine);
        Map(x => x.Template);
        Map(x => x.StageOrder);
        Map(x => x.CorrespondenceType).CustomTypeIs(typeof (ActionCorrespondenceTypeEnumType));
        References(x => x.Matter).FetchType.Join();
        HasMany(x => x.FileNotes).Cascade.SaveUpdate();

        DiscriminateSubClassesOnColumn("Type")
            .SubClass<SlidingAction>(/*its forcing me to map something here*/);
    }
}

Best Answer

Just put an empty lambda in, c => {}.

.SubClass<SlidingAction>(c => {});

Related Solutions

C# – Fluent NHibernate, joined-subclass mapping

I think the API has changed since this question was asked, but this works for me:

public class SomeSubclassMap : SubclassMap<SomeSubclass> {
    public SomeSubclassMap()
    {
        KeyColumn("SomeKeyColumnID");
        Map(x => x.SomeSubClassProperty);
        ...
    }
}

I believe KeyColumn is only required if it's different than 'Baseclassname_id'

Note: There should also be a ClassMap<SomeBaseClass> for the base class that SomeSubClass extends.

C# – Fluent NHibernate table per hierarchy mapping problem

I figured it out in case of enums.

Considering this enum type:

public enum ActivityType
{
    [EnumKey("1")]
    [EnumDescription("ImportFromFile")]
    ImportFromFile,
}

where EnumKey and EnumDescription are (popular) extension methods, I redefine Activity like

public abstract class Activity
    {
        public virtual Guid Id { get; set; }
        public virtual ActivityExecutionResult ExecutionResult { get; private set; }

        public virtual ActivityExecutionStatus ExecutionStatus {get;private set;}

        public abstract ActivityExecutionStatus Execute();

        public virtual string ActivityName { get; private set; }

        public virtual IDictionary<string, string> ActivityParameters { get; private set; }

        public virtual ActivityType ActivityType { get; private set; }
    }

The mapping file looks like this:

public class ActivityMap : ClassMap<Activity>
    {
        public ActivityMap()
        {
            Table("Activities");
            Id(x => x.Id).Column("ID").GeneratedBy.Guid();
            Map(x => x.ActivityName).Not.Nullable().Length(50);
            Map(x => x.ActivityType).CustomType<int>().Column("ActivityType").Not.Nullable();
            HasMany(x => x.ActivityParameters)
                .KeyColumn("ActivityID")
                .AsMap<string>(idx => idx.Column("ParameterName"), elem => elem.Column("ParameterValue"))
                .Not.LazyLoad()
                .Cascade.Delete()
                .Table("ActivityParameters");

            DiscriminateSubClassesOnColumn("ActivityType");
        }
    }

    public class ImportActivityFromFileMap : SubclassMap<ImportActivityFromFile>
    {
        public ImportActivityFromFileMap()
        {
            DiscriminatorValue(ActivityType.ImportFromFile.GetKey());
        }
    }

The generated hbm file looks like:

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" default-access="property" auto-import="true" default-cascade="none" default-lazy="true">
  <class xmlns="urn:nhibernate-mapping-2.2" name="***.Activity, ***, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" table="Activities">
    <id name="Id" type="System.Guid, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
      <column name="ID" />
      <generator class="guid" />
    </id>
    <discriminator column="ActivityType" type="String" insert="true" not-null="true" />
    <property name="ActivityName" type="System.String, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
      <column name="ActivityName" length="50" not-null="true" />
    </property>
    <property name="ActivityType" type="Int32">
      <column name="ActivityType" not-null="true" />
    </property>
    <map cascade="delete" lazy="false" name="ActivityParameters" table="ActivityParameters">
      <key>
        <column name="ActivityID" />
      </key>
      <index type="System.String, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
        <column name="ParameterName" />
      </index>
      <element type="System.String, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
        <column name="ParameterValue" />
      </element>
    </map>
    <subclass name="***.ImportActivityFromFile, ***, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" discriminator-value="1" />
  </class>
</hibernate-mapping>

It works like a charm!

Best Answer

Related Solutions

C# – Fluent NHibernate, joined-subclass mapping

C# – Fluent NHibernate table per hierarchy mapping problem

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