I'm accustomed to seeing "No persister for:" errors when I don't have a
class map defined for one of my classes, but not for an internal NHibernate
class.
I'm the getting this exception when I attempt to access the Tasks collection
defined in the following relationship. It doesn't make a difference if the
collection is eager or lazy loaded, except that if it is lazy loaded, the
exception isn't thrown until I try to access the collection, so it seems
that the exception is the result of NHibernate trying to query for the
collection.
I'm using the Fluent API for the mappings, but I've included the resulting
hbm.xml file below.
*TaskContainer* (base class)
public abstract class TaskContainer : DomainObject{
public virtual IList<Task> Tasks { get; set; }}
*Task*
public class Task : TaskContainer{
public virtual TaskContainer TaskContainer { get; set; }
public virtual string Description { get; set; }
public virtual void AddChildTask(Task childTask)
{
if (Tasks == null)
{
Tasks = new List<Task>();
}
childTask.TaskContainer = this;
Tasks.Add(childTask);
}
public static Task Get(int id)
{
return Get<Task>(id);
}}
*TaskMap*
public class TaskMap : ClassMap<Task>{
public TaskMap()
{
Id(x => x.Id);
Map(x => x.Description);
ReferencesAny(x => x.TaskContainer)
.EntityIdentifierColumn("TaskContainer_Id")
.EntityTypeColumn("TaskContainerDiscriminator")
.IdentityType<int>()
.AddMetaValue<Task>("Task");
HasMany(x => x.Tasks)
.KeyColumns.Add("TaskContainer_Id", "TaskContainerDiscriminator")
.PropertyRef("TaskContainer")
.Not.LazyLoad();
}}
*Exported hbm.xml map*
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" default-cascade="all">
<class xmlns="urn:nhibernate-mapping-2.2" lazy="false"
name="CubeNet.Service.DomainObjects.Task, CubeNet.Service, Version=1.0.0.0,
Culture=neutral, PublicKeyToken=null" table="`Task`">
<id name="Id" type="System.Int32, mscorlib, Version=4.0.0.0,
Culture=neutral, PublicKeyToken=b77a5c561934e089">
<column name="Id" />
<generator class="identity" />
</id>
<bag name="Tasks">
<key property-ref="TaskContainer">
<column name="TaskContainer_Id" />
<column name="TaskContainerDiscriminator" />
</key>
<one-to-many class="CubeNet.Service.DomainObjects.Task, CubeNet.Service,
Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
</bag>
<property name="Description" type="System.String, mscorlib,
Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
<column name="Description" />
</property>
<any id-type="System.Int32, mscorlib, Version=4.0.0.0, Culture=neutral,
PublicKeyToken=b77a5c561934e089" meta-type="System.String, mscorlib,
Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"
name="TaskContainer">
<meta-value value="Task" class="CubeNet.Service.DomainObjects.Task,
CubeNet.Service, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
<column name="TaskContainerDiscriminator" />
<column name="TaskContainer_Id" />
</any>
</class></hibernate-mapping>
Saving records with this configuration works as expected and produces the
following table with these records
Id Description TaskContainerDiscriminator TaskContainer_Id-- -----------
-------------------------- ----------------1 Parent task NULL
NULL2 Child Task Task 1
Retrieving the either record works, but the exception is thrown when
attempting to access the collection of child records.
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