The simplest way to follow this explanation is a NServiceBus Pub/Sub sample which contains example of "polymorphic subscriptions" (Subscriber2).
Messages: (without changes)
public class EventMessage : IEvent
{
public Guid EventId { get; set; }
public DateTime? Time { get; set; }
public TimeSpan Duration { get; set; }
}
public interface IEvent : IMessage
{
Guid EventId { get; set; }
DateTime? Time { get; set; }
TimeSpan Duration { get; set; }
}
Handler: (without changes)
public class EventMessageHandler : IHandleMessages<IEvent>
{
public void Handle(IEvent message)
{
// ...
}
}
This handler will receive both IEvent and EventMessage messages. But if I will make IEvent a class...
public class IEvent : IMessage
{
Guid EventId { get; set; }
DateTime? Time { get; set; }
TimeSpan Duration { get; set; }
}
...then i will not be able to receive EventMessage but will receive IEvent as before
So i found such simple rule: if you use interface in IHandleMessages<> - it will work, if class - it will not work. Currently i have all messages as classes and i would like to subscribe to parent class message in order to receive all child class messages.
Is it intended behavior?
This is all by design in order to enable multiple inheritance. The reasons to do so are detailed here. Publicly available events between Business Components are recommended to be modeled as interfaces, commands within a business component are recommended to be modeled as classes. Sounds like you want this behaviour, I would switch over to interfaces.
Related
Currently, I want to pass an object type to the message to avoid reading the DB twice.
But my solution which has the RabbitMQ is not a reference to the domain entities, it only has the abstract class and the interface of the entities.
So, Is there any way to pass an abstract class or interface to the message of the RabbitMQ?
Thank you for your advices!
public interface IDomainEntity
{
// The rest of the code
}
public abstract class Person
{
// The rest of the code
}
public class Employee
{
// The rest of the code
}
public class Employee: IDomainEntity, Person
{
// The rest of the code
}
public class RefreshEmployeeCache : CorrelatedBy<Guid>
{
public Guid EmployeeId { get; set; }
public Person Employee { get; set; } // or public IDomainEntity Employee { get; set; } Can we use this or an althernative way?
public bool IsDeleted { get; set; }
public Guid CorrelationId { get; set; } = Guid.NewGuid();
}
You should be able to cast the message to an object, which should use the Publish(object message) overload (or the Send(object message) overload), allows whatever concrete type is present to be published.
Consumers can implement IConsumer<Person>, providing access to the properties of Person. The subclass type would only be available if it is known to the consumer and requested specifically.
I currently have a working one-to-many relationship between the entities 'Conversation' and 'Message', where a conversation can have multiple messages.
This works fine:
public class Conversation
{
public long ID { get; set; }
}
public class Message : IEntity
{
public virtual Conversation Conversation { get; set; }
public long ConversationID { get; set; }
public long ID { get; set; }
}
However, I am trying to add a navigation property to the 'Conversation' class called 'LastMessage' which will keep track of the last message record that was created:
public class Conversation
{
public long ID { get; set; }
public virtual Message LastMessage { get; set; }
public long LastMessageID { get; set; }
}
When I try to apply the above, I get the error
System.InvalidOperationException: The child/dependent side could not
be determined for the one-to-one relationship between
'Conversation.LastMessage' and 'Message.Conversation'.
How do I maintain a one-to-many relationship between 'Conversation' and 'Message', but ALSO add a navigation property in the 'Conversation' class that navigates to a single 'Message' record?
If conversation can have several messages it is called one-to-many relations.
You have to fix the tables:
public class Conversation
{
[Key]
public long ID { get; set; }
[InverseProperty(nameof(Message.Conversation))]
public virtual ICollection<Message> Messages { get; set; }
}
public class Message
{
[Key]
public long ID { get; set; }
public long ConversationID { get; set; }
[ForeignKey(nameof(ConversionId))]
[InverseProperty("Messages")]
public virtual Conversation Conversation { get; set; }
}
After trying all sorts of Data Annotations and Fluent API nonsense, the cleanest solution I could come up with turned out to be very simple which requires neither. It only requires adding a 'private' constructor to the Conversation class (or a 'protected' one if you're using Lazy Loading) into which your 'DbContext' object is injected. Just set up your 'Conversation' and 'Message' classes as a normal one-to-many relationship, and with your database context now available from within the 'Conversation' entity, you can make 'LastMessage' simply return a query from the database using the Find() method. The Find() method also makes use of caching, so if you call the getter more than once, it will only make one trip to the database.
Here is the documentation on this ability: https://learn.microsoft.com/en-us/ef/core/modeling/constructors#injecting-services
Note: the 'LastMessage' property is read-only. To modify it, set the 'LastMessageID' property.
class Conversation
{
public Conversation() { }
private MyDbContext Context { get; set; }
// make the following constructor 'protected' if you're using Lazy Loading
// if not, make it 'private'
protected Conversation(MyDbContext Context) { this.Context = Context; }
public int ID { get; set; }
public int LastMessageID { get; set; }
public Message LastMessage { get { return Context.Messages.Find(LastMessageID); } }
}
class Message
{
public int ID { get; set; }
public int ConversationID { get; set; }
public virtual Conversation Conversation { get; set; }
}
I get this webservice error sometimes on a SL5 + EF + WCF app.
"Parameter 'role' of domain operation entry 'AddUserPresentationModelToRole' must be one of the predefined serializable types."
here is a similar error, however his solution doesn't work for me.
I have the codegenned DomainService which surfaces the database entities to my client:
[EnableClientAccess()]
public partial class ClientAppDomainService : LinqToEntitiesDomainService<ClientAppUserEntitlementReviewEntities>
{
public IQueryable<Account> GetAccounts()
{
return this.ObjectContext.Accounts;
}
//..etc...
and my custom service which is surfacing a Presentation model, and db entities.
[EnableClientAccess]
[LinqToEntitiesDomainServiceDescriptionProvider(typeof(ClientAppUserEntitlementReviewEntities))]
public class UserColourService : DomainService
{
[Update(UsingCustomMethod = true)]
public void AddUserPresentationModelToRole(UserPresentationModel userPM, Role role, Reviewer reviewer)
{
...
}
public IDictionary<long, byte> GetColourStatesOfUsers(IEnumerable<RBSUser> listOfUsers, string adLogin)
{
//....
}
}
and the PresentationModel:
public class UserPresentationModel
{
[Key]
public long UserID { get; set; }
public byte UserStatusColour { get; set; }
public string MessageText { get; set; }
[Include]
[Association("asdf", "UserID", "UserID")]
public EntityCollection<Account> Accounts { get; set; }
public DateTime AddedDate { get; set; }
public Nullable<long> CostCentreID { get; set; }
public DateTime? DeletedDate { get; set; }
public string EmailAddress { get; set; }
public long EmployeeID { get; set; }
public string FirstName { get; set; }
public Nullable<bool> IsLeaver { get; set; }
public string LastName { get; set; }
public DateTime LastSeenDate { get; set; }
public string LoginDomain { get; set; }
public string LoginName { get; set; }
public byte WorldBuilderStatusID { get; set; }
}
Also cannot get the solution to reliably fail. It seems whenever I change the service slightly ie make it recompile, everything works.
RIAServices unsupported types on hand-built DomainService - seems to be saying the same thing, that decorating the hand built services with the LinqToEntitiesDomainServiceDescriptionProvider should work.
Possible answer here will post back here too with results.
From Colin Blair:
I am a bit surprised it ever works, I don't think I have seen anyone trying to pass additional entiities into a named update before. It might be a bug in RIA Services that it is working at all. What are you trying to accomplish?
Side note, you have a memory leak with your ObjectContext since it is not getting disposed of correctly. Is there a reason you aren't using the LinqToEntitiesDomainSerivce? It would take care of managing the ObjectContext's lifetime for you.
Results:
1) This makes sense. Have refactored out to more sensible parameters now (ints / strings), and all working.
2) Have brought together my 3 separate services into 1 service, which is using the LinqToEntitiesDomainSerivce. The reason I'd split it out before was the assumption that having a CustomUpdate with a PresentationModel didn't work.. and I had to inherit off DomainService instead. I got around this by making a method:
// need this to avoid compile errors for AddUserPresentationModelToRole.. should never be called
public IQueryable<UserPresentationModel> GetUserPresentationModel()
{
return null;
}
We're using RavenDB saga storage, but the saga data isn't being persisted after the starting message handler. I only see a handful of subscription documents in the database. I'm not sure what to check next. Ideas?
I have a saga:
public class BuyerWaitingOnDocumentsDistributor :
Saga<BuyerDocumentDistributorData>,
IAmStartedByMessages<DocumentVersionRequiresBuyerSignature>
{
public void Handle(DocumentVersionRequiresEmployeeSignature message)
{
Data.DocumentVersionId = message.DocumentVersionId.Value;
// Business logic goes here
}
// Other handlers & methods here
}
and saga entity:
public class BuyerDocumentDistributorData : IContainSagaData
{
public virtual Guid Id { get; set; }
public virtual string Originator { get; set; }
public virtual string OriginalMessageId { get; set; }
public virtual Guid DocumentVersionId { get; set; }
public virtual EmployeeId[] AuthorizedToSign { get; set; }
}
and saga finder:
public class BuyerWaitingOnDocumentsDistributorSagaFinder :
IFindSagas<BuyerDocumentDistributorData>.Using<DocumentVersionRequiresBuyerSignature>,
IFindSagas<BuyerDocumentDistributorData>.Using<DocumentVersionSignedByBuyer>,
IFindSagas<BuyerDocumentDistributorData>.Using<DocumentVersionNoLongerRequiresSignature>
{
private static readonly ILog Log = LogManager.GetLogger(typeof (BuyerWaitingOnDocumentsDistributorSagaFinder));
public ISagaPersister Persister { get; set; }
public BuyerDocumentDistributorData FindBy(DocumentVersionRequiresBuyerSignature message)
{
return Persister.Get<BuyerDocumentDistributorData>("DocumentVersionId", message.DocumentVersionId.Value);
}
public BuyerDocumentDistributorData FindBy(DocumentVersionSignedByBuyer message)
{
return Persister.Get<BuyerDocumentDistributorData>("DocumentVersionId", message.DocumentVersionId.Value);
}
public BuyerDocumentDistributorData FindBy(DocumentVersionNoLongerRequiresSignature message)
{
return Persister.Get<BuyerDocumentDistributorData>("DocumentVersionId", message.DocumentVersionId.Value);
}
}
I've also asked this question on the NServiceBus Yahoo group: http://tech.groups.yahoo.com/group/nservicebus/message/13265
You did not give your endpointconfig, so I'm unsure which container you are using.
We experience the same (saga not getting persisted) when using the NinjectBuilder. Using the DefaultBuilder works ok.
I would like to send a list of Appointments through WCF. My Interface looks like this:
[ServiceContract]
public interface IServices
{
[OperationContract]
string addAppointments(List<Appointment> appointmentList);
}
If I call my WCF Service I'm always getting the following error:
Type 'Microsoft.Exchange.WebServices.Data.Appointment' cannot be
serialized. Consider marking it with the DataContractAttribute
attribute, and marking all of its members you want serialized with the
DataMemberAttribute attribute. See the Microsoft .NET Framework
documentation for other supported types.
My Service currently looks like this:
class Service : IServices
{
public string addAppointments(List<Appointment> appointmentList)
{
foreach (Appointment app in appointmentList)
{
Console.WriteLine(app.Organizer.Name);
}
return "true";
}
}
It's not your service that's at fault, it's the class your passing, Appointment.
Start by adding [DataContract] to your class. then [DataMember] to each of the properties you'd like to pass.
For example, if you started with:
public class Appointment{
public DateTime Date { get; set; }
public string Name { get; set; }
}
You can make it serializable by WCF's DataContractSerializer by adding those attributes:
[DataContract]
public class Appointment{
[DataMember]
public DateTime Date { get; set; }
[DataMember]
public string Name { get; set; }
}