Need help with NHibernate / Fluent NHibernate mapping?

Many-to-any If the table structure is fixed, and you want to use the identity id generator, I would map the Source tables as 3 separate classes and map to the common interface as an any reference class Case { public virtual IReferral Referral { get; set; } } class SourceA : IReferral { public virtual int Id { get; set; } public virtual string Name { get; set; } public virtual string Type { get { return "SourceA"; } } } interface IReferral { int Id { get; set; } string Name { get; set; } string Type { get; } } public class CaseMap : ClassMap { public CaseMap() { ReferencesAny(m => m. Referral) . EntityTypeColumn("ReferralType") .

EntityIdentifierColumn("ReferralId") . AddMetaValue("SourceA") . AddMetaValue("SourceB") .

AddMetaValue("SourceC") .IdentityType(); } } union-subclass Another option is union-subclass with an abstract base class mapping. This allows eager fetching, but you cannot use the identity generator on the subclass tables class name="IReferral" abstract="true" table="Referral".

Many-to-any If the table structure is fixed, and you want to use the identity id generator, I would map the Source tables as 3 separate classes and map to the common interface as an any reference. Class Case { public virtual IReferral Referral { get; set; } } class SourceA : IReferral { public virtual int Id { get; set; } public virtual string Name { get; set; } public virtual string Type { get { return "SourceA"; } } } interface IReferral { int Id { get; set; } string Name { get; set; } string Type { get; } } public class CaseMap : ClassMap { public CaseMap() { ReferencesAny(m => m. Referral) .

EntityTypeColumn("ReferralType") . EntityIdentifierColumn("ReferralId") . AddMetaValue("SourceA") .

AddMetaValue("SourceB") . AddMetaValue("SourceC") .IdentityType(); } } union-subclass Another option is union-subclass with an abstract base class mapping. This allows eager fetching, but you cannot use the identity generator on the subclass tables.

Subclass If you can change the tables, you can map all 3 Referral classes to the same table using subclass.

I can't seem to get your sample working. I'm getting a "Not a member access Parameter name: expression" error – Mark Boltuc Mar 17 '10 at 3:03 I managed to get it working (see my answer). Thanks for the help Lachlan.

– Mark Boltuc Mar 17 '10 at 16:19.

ReferralId { get; protected set; } public virtual string Name { get { return null; } //NOTE: We need this for mapping reasons protected virtual int CaseId { get; set; } protected CaseReferral() { } } public class CaseSourceAReferral : CaseReferral { private SourceA _sourceA; public virtual SourceA Source { get { return _sourceA; } protected set { _sourceA = value; Type = "SourceA"; ReferralId = ( _sourceA! = null? _sourceA.

Id : null ); } } public override string Name { get { return Source.Name; } } //NOTE: Default constructor for mapping reasons protected CaseSourceAReferral() { } public CaseSourceAReferral( int caseId, SourceA source ) { CaseId = caseId; Source = source; } } public class CaseMap : ClassMap { public CaseMap() { Id( c => c. Id ); References( c => c. Referral ).

Column( "Id" ); } } public class CaseReferralMap : ClassMap { public CaseReferralMap() { Id( Reveal. Property( "CaseId") ). Column( "Id" ); Map( r => r.

Type ). Column( "ReferralType" ); Map( r => r. ReferralId ).

Column( "ReferralId" ); DiscriminateSubClassesOnColumn( "ReferralType" ); } } public class CaseSourceAReferralMap : SubclassMap { public CaseSourceAReferralMap() { DiscriminatorValue( "SourceA" ); References( r => r. Source ). Column( "ReferralId" ); } }.

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