“Entity does not have a key defined” error in working production code

1
votes

We are running into a very odd problem: We are using entity framework 4 and ria services for a silverlight 5 appliation hosted in IIS 6.1. For long periods of time, everything is running smoothly, but occasionally the application fails with the following error message in the event log:

WebHost failed to process a request.
Sender Information: System.ServiceModel.Activation.HostedHttpRequestAsyncResult/56703158
Exception: System.ServiceModel.ServiceActivationException: The service '/Services/EcoFleet-DomainServices-Repository-EcofleetRepository.svc' cannot be activated due to an exception during compilation.
The exception message is: The Entity 'DeviceData' in DomainService 'EcofleetRepository' does not have a key defined. Entity types exposed by DomainService operations must have at least one public property marked with the KeyAttribute.. ---> System.InvalidOperationException: The Entity 'DeviceData' in DomainService 'EcofleetRepository' does not have a key defined. Entity types exposed by DomainService operations must have at least one public property marked with the KeyAttribute.
at System.ServiceModel.DomainServices.Server.DomainServiceDescription.ValidateEntityTypes()
at System.ServiceModel.DomainServices.Server.DomainServiceDescription.Initialize()
at System.ServiceModel.DomainServices.Server.DomainServiceDescription.CreateDescription(Type domainServiceType)
at System.Collections.Concurrent.ConcurrentDictionary2.GetOrAdd(TKey key, Func2 valueFactory)
at System.ServiceModel.DomainServices.Server.DomainServiceDescription.GetDescription(Type domainServiceType)
at System.ServiceModel.DomainServices.Hosting.DomainServiceHost..ctor(Type domainServiceType, Uri[] baseAddresses)
at System.ServiceModel.DomainServices.Hosting.DomainServiceHostFactory.CreateServiceHost(Type serviceType, Uri[] baseAddresses)
at System.ServiceModel.Activation.ServiceHostFactory.CreateServiceHost(String constructorString, Uri[] baseAddresses)
at System.ServiceModel.ServiceHostingEnvironment.HostingManager.CreateService(String normalizedVirtualPath, EventTraceActivity eventTraceActivity)
at System.ServiceModel.ServiceHostingEnvironment.HostingManager.ActivateService(ServiceActivationInfo serviceActivationInfo, EventTraceActivity eventTraceActivity)

at System.ServiceModel.ServiceHostingEnvironment.HostingManager.EnsureServiceAvailable(String normalizedVirtualPath, EventTraceActivity eventTraceActivity)

--- End of inner exception stack trace ---
at System.Runtime.AsyncResult.End[TAsyncResult](IAsyncResult result)
at System.ServiceModel.Activation.HostedHttpRequestAsyncResult.End(IAsyncResult result) Process Name: w3wp
Process ID: 2300

The application still responds, but no entities can be loaded from the server. After stopping and starting the site, everything works again.

The entity in this case (DeviceData) is a database table, and it does have a key, and regardless it seems to be random which entity fails. Furthermore I would only expect to see the "key not defined" error at compile time. Does anyone have a clue what the problem is, and how to fix it?

2
entity-frameworksilverlightiiswcf-ria-servicesria
I hate ria services. But use it. It is very slow at compile time and has many restrictions. If you use a code generator check if [Key] is really generating for item. I just use t4 rarely. EDMX seems better for this kind of issues. - Davut Gürbüz
It isn't generating the attribute, but I still don't understand why it would cause it to only break randomly, only to magically fix itself by restarting the site... However I will try and change the generator, and see if it fixes it. - sondergard
Have you ever found a solution for this problem? We're experiencing the same problem as well. - Lars P.
@LarsP. I have changed job in the mean time, and I don't recall any more if we found a real fix, or if it just magically fixed itself... - sondergard

2 Answers

1
votes

Your DeviceData entity do not have key defined, which is required. You should create property with name Id or DeviceDataId which will be treated as key by convention (Entity Framework currently looks for these properties). Also you can use mappings to set other property as key. This can be achieved with data annotations attributes:

[Key]
public int Foo { get; set; }

Or with fluent mappings:

modelBuilder.Entity<DeviceData>().HasKey(d => d.Foo);
0
votes

First you won't have an error at compile time because it is not a mandatory thing, but not having one might give you quite the headache, because EF use it in many ways. so you have to redefine your key by naming it Id or DeviceDataId(Using the convention) or define a one from the model.

It seems from your question that there is a key defined for DeviceData, in that case I advice you to relook the properties of the key column in your model.

remember also that not having a key column might reduce the performance of your app.