The entity type 'Configuration' requires a primary key to be defined

Question

When I try to use Add-Migration I get this error:

The entity type 'Configuration' requires a primary key to be defined.

Now, I know that entities need keys, and it has one, but so far, simply decorating a property with [Key] did the job, but it doesn't seem to be so anymore. So i have the following entity:

public class Configuration
{
    [Key, ForeignKey("Client")]
    public int ClientId { get; set; }

    public CommunicationType CommunicationType { get; set; }

    public string CommunicationValue { get; set; }

    public virtual Client Client { get; set; }
}

But after searching for a while, I found out that apparently EF7 doesn't like it's conventions to be breached, and I need to rename ClientId to ConfigurationId, but that seems wrong to my coding conventions. Do i have to change my ways or is there anyway to bypass this? Thanks in advance.

---

edit

Here's the Client entity, and yes, there's a Configuration property there

public class Client
{
    [Key]
    public int ClientId { get; set; }

    public string Name { get; set; }

    public virtual User User { get; set; }

    public virtual List<Station> Stations { get; set; }

    public Configuration Configuration { get; set; }
}

---

edit

Full error log:

System.InvalidOperationException: The entity type 'Configuration' requires a primary key to be defined.
   in Microsoft.EntityFrameworkCore.Internal.ModelValidator.ShowError(String message)
   in Microsoft.EntityFrameworkCore.Internal.ModelValidator.EnsureNonNullPrimaryKeys(IModel model)
   in Microsoft.EntityFrameworkCore.Internal.ModelValidator.Validate(IModel model)
   in Microsoft.EntityFrameworkCore.Internal.RelationalModelValidator.Validate(IModel model)
   in Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.CreateModel(DbContext context, IConventionSetBuilder conventionSetBuilder, IModelValidator validator)
   in Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.c__DisplayClass14_0.b__0(Object k)
   in System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
   in Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.GetModel(DbContext context, IConventionSetBuilder conventionSetBuilder, IModelValidator validator)
   in Microsoft.EntityFrameworkCore.Internal.DbContextServices.CreateModel()
   in Microsoft.EntityFrameworkCore.Internal.LazyRef`1.get_Value()
   in Microsoft.EntityFrameworkCore.Internal.DbContextServices.get_Model()
   in Microsoft.EntityFrameworkCore.Infrastructure.EntityFrameworkServiceCollectionExtensions.c.b__0_6(IServiceProvider p)
   in Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitFactoryService(FactoryService factoryService, ServiceProvider provider)
   in Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(IServiceCallSite callSite, TArgument argument)
   in Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScoped(ScopedCallSite scopedCallSite, ServiceProvider provider)
   in Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(IServiceCallSite callSite, TArgument argument)
   in Microsoft.Extensions.DependencyInjection.ServiceProvider.c__DisplayClass16_0.b__0(ServiceProvider provider)
   in Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(Type serviceType)
   in Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetService[T](IServiceProvider provider)
   in Microsoft.EntityFrameworkCore.Design.Internal.DesignTimeServicesBuilder.c__DisplayClass6_0.b__9(IServiceProvider _)
   in Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitFactoryService(FactoryService factoryService, ServiceProvider provider)
   in Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(IServiceCallSite callSite, TArgument argument)
   in Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitTransient(TransientCallSite transientCallSite, ServiceProvider provider)
   in Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(IServiceCallSite callSite, TArgument argument)
   in Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, ServiceProvider provider)
   in Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(IServiceCallSite callSite, TArgument argument)
   in Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitTransient(TransientCallSite transientCallSite, ServiceProvider provider)
   in Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(IServiceCallSite callSite, TArgument argument)
   in Microsoft.Extensions.DependencyInjection.ServiceProvider.c__DisplayClass16_0.b__0(ServiceProvider provider)
   in Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(Type serviceType)
   in Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
   in Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)
   in Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.AddMigration(String name, String outputDir, String contextType)
   in Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name, String outputDir, String contextType)
   in Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigration.c__DisplayClass0_1.b__0()
   in Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.c__DisplayClass3_0`1.b__0()
   in Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
The entity type 'Configuration' requires a primary key to be defined.

Answer 1

Have you tried moving the ForeignKey attribute to the navigation property?

public class Configuration
{
    [Key]
    public int ClientId { get; set; }

    public CommunicationType CommunicationType { get; set; }

    public string CommunicationValue { get; set; }

    [ForeignKey("ClientId")]
    public virtual Client Client { get; set; }
}