Key is already present in this dictionary error

If i used a Sequence(Sql Server 2012) as a central key service like

 I just wrote a little service today to do this, for my project. So far I've only done a fake store implementation. For a real implementation you would simply use a remote service method, and then on the server side execute your query to get the next id.

public interface IKeyService<T> : IHideObjectMembers     {         Task AllocateRange(int count);         Task<T> GetNext();     }

public class FakeStoreIntegerKeyService : IKeyService<int>     {         private int _nextId;         private readonly Queue<int> _availableKeys;         public FakeStoreIntegerKeyService()         {             _nextId = 1;             _availableKeys = new Queue<int>();         }         #region Implementation of IKeyService<int>         public Task AllocateRange(int count)         {             for (var i = 0; i < count; i++)             {                 _availableKeys.Enqueue(_nextId++);             }             return TaskFns.FromResult(true);         }         public Task<int> GetNext()         {            if (_availableKeys.Count == 0)                AllocateRange(1);             return TaskFns.FromResult(_availableKeys.Dequeue());         }         #endregion     }

I have multiple models so I just made an interface for this specific model so I'm not sharing keys between different models. You could bypass this step.

public interface IDemoKeyService : IKeyService<int>     {     }   public class DemoFakeKeyService : FakeStoreIntegerKeyService, IDemoKeyService     {     }

I then subclassed Factory<T> to include my Key Service

public class DemoFactory<T> : Factory<T>         where T : Entity     {         private readonly IDemoKeyService _keyService;         public DemoFactory(IEntityManagerProvider<DemoEntities> entityManagerProvider, IDemoKeyService keyService)             : base(entityManagerProvider)         {             _keyService = keyService;         }         public override async System.Threading.Tasks.Task<T> CreateAsync(System.Threading.CancellationToken cancellationToken)         {             var entity = await base.CreateAsync(cancellationToken);             cancellationToken.ThrowIfCancellationRequested();             var key = await _keyService.GetNext();             cancellationToken.ThrowIfCancellationRequested();             SetKey(entity, key);             return await TaskFns.FromResult(entity);         }         private void SetKey(T entity, int key)         {             var keyProperty = entity.EntityAspect.EntityMetadata.KeyProperties.FirstOrDefault();             entity.EntityAspect.SetValue(keyProperty, key);         }     }

In my sample project I have a Customer and a CustomerAddress table. Previously I could do Customer.AddAddress() but I wasn't sure the cleanest way to implement that anymore. So I simply made a new Factory class to handle this:

public class CustomerFactory : ICustomerFactory     {         private readonly DemoFactory<Customer> _customerFactory;         private readonly DemoFactory<CustomerAddress> _customerAddressFactory;         public CustomerFactory(IEntityManagerProvider<DemoEntities> entityManagerProvider, IDemoKeyService keyService)         {             _customerFactory = new DemoFactory<Customer>(entityManagerProvider, keyService);             _customerAddressFactory = new DemoFactory<CustomerAddress>(entityManagerProvider, keyService);         }         #region Implementation of ICustomerFactory         public Task<Customer> CreateCustomer()         {             return _customerFactory.CreateAsync(CancellationToken.None);         }         public async Task<CustomerAddress> CreateAddress(int customerId)         {             var address = await _customerAddressFactory.CreateAsync();             address.CustomerId = customerId;             return await TaskFns.FromResult(address);         }         #endregion     }

I then expose the ICustomerFactory on my UnitOfWork. I can then simply do:

Address = await UnitOfWork.CustomerFactory.CreateAddress(Customer);

If Marcel has a better way of doing this, I'm all ears. Hopefully this will give you enough to get started though.





Edited by smi-mark - 03-Oct-2012 at 6:08am

Good point. I have changed that now.

Can you change the Factory class to also find internal methods? I've set InternalsVisibleTo to my DomainServices project, but of course Factory<> only looks for Public | Static right now. I will add it as a task on the tracker.