We are developing windows service, and i want to change dbcontext class dynamically in repositories.
bellow is the scenario.
I have three db context classes
public abstract class Context : DbContext, IUnitOfWork
{
protected Context(string connectionString) : base(connectionString)
{
}
}
public class PlatformContext : Context
{
private readonly string _connectionString;
public PlatformContext(string connectionString)
: base(connectionString)
{
_connectionString = connectionString;
}
}
public class PlatformReplicaContext : Context
{
private readonly string _connectionString;
public PlatformReplicaContext(string connectionString)
: base(connectionString)
{
_connectionString = connectionString;
}
}
public class TempContext : Context
{
private readonly string _connectionString;
public TempContext(string connectionString)
: base(connectionString)
{
_connectionString = connectionString;
}
}
and i have repository
public interface ICategoryRepository : IRepository<Category>
{
}
public class CategoryRepository :Repository<Category>, ICategoryRepository
{
public CategoryRepository(Context context) : base(context)
{
}
}
hence im using CQRS i have another three classes
public class CategoryBasicQuery:IRequest<BaseQueryResponse>
{
public int CategoryId { get; set; }
}
public class CategoryBasicQueryHandler : IRequestHandler<CategoryBasicQuery, BaseQueryResponse>
{
private readonly ICategoryRepository _categoryRepository;
private readonly IMapper _mapper;
public CategoryBasicQueryHandler(ICategoryRepository categoryRepository, IMapper mapper)
{
_categoryRepository = categoryRepository;
_mapper = mapper;
}
public async Task<BaseQueryResponse> Handle(CategoryBasicQuery request, CancellationToken cancellationToken)
{
var entry = await _categoryRepository.FindAsync(request.CategoryId);
if (entry == null)
{
return new NotFoundResponse();
}
var response = _mapper.Map<CategoryBasicResponse>(entry);
return response;
}
}
Now here is the issue
Here category repository should be able to execute queries in all 3 types of contexts.
but how should i register classes in using autofac?
then i came up with a solution generating repositories in run time as below
public class RepositoryFactory
{
public static TRepository GetRepositoryInstance<T, TRepository>(
params object[] args)
where TRepository : IRepository<T>
{
return (TRepository)Activator.CreateInstance(typeof(TRepository), args);
}
}
im calling this method inside CategoryBasicQueryHandler class like this
var categoryRepo = RepositoryFactory.GetRepositoryInstance<Category, CategoryRepository>(new PlatformReplicaContext("connectionString"));
but when calling from CQRS
var categoty = new Category();
var command = new CategoryBasicQuery {CategoryId = categoryId};
var result = _mediator.Send(command);
VS give me following error
and my autofac registration as follows
builder.RegisterType<CategoryService>().AsSelf();
builder.RegisterType<ActionRepository>().As<IActionRepository>();
builder.RegisterType<CategoryRepository>().As<ICategoryRepository>();
builder.RegisterType<Mapper>().As<IMapper>();
can anyone help me resolve this or suggest good method to handle this situation.
thanks.
This may give you a good starting point for a possible solution: http://autofaccn.readthedocs.io/en/latest/resolve/relationships.html#keyed-service-lookup-iindex-x-b
builder.RegisterType<PlatformContext>().Keyed<Context>("platform");
builder.RegisterType<PlatformReplicaContext>().Keyed<Context>("replica");
builder.RegisterType<TempContext>().Keyed<Context>("temp");
You mentioned in a comment that there is a variable named action somewhere that will indicate which implementation to use:
public class Class1
{
private readonly IIndex<string, Context> contexts;
public Class1(IIndex<string, Context> contexts)
{
this.contexts = contexts;
}
public void Whatever()
{
string action = ...; // platform, replica or temp
Context context = this.contexts[action];
...
}
}
Of course this needs to be adapted so that it will fit in the rest of your application design. A possible example could be:
Context context = this.contexts[action];
using(ILifetimeScope scope = container.BeginLifetimeScope(builder =>
{
builder.RegisterInstance(context).As<Context>();
}))
{
// Because we are resolving IMediator from the scope, the selected Context will be used in all dependencies
var mediator = scope.Resolve<IMediator>();
mediator.Send(...);
}
Related
I'm very new to ASP.NET Web API and I'm trying to use Entity Framework Core's Dependency Injection to POST data to the API Controller using MediatR pattern. But every time I run my code and it opens Swagger UI, I get an error 500 response saying
Unable to cast object of type 'AsyncStateMachineBox1[System.Threading.Tasks.VoidTaskResult,S3E1.Repository.CartItemRepository+<Createitem>d__5]' to type 'System.Threading.Tasks.Task1[S3E1.Entities.CartItemEntity]'.
First, I added Dependency Injections to Program.cs
//Dependency Injection
builder.Services.AddDbContext<AppDataContext>(contextOptions => contextOptions.UseSqlServer(
builder.Configuration.GetConnectionString("DefaultConnection")
));
//Connection
builder.Services.AddSingleton<DataConnectionContext>();
These are the classes.
AppDataContext.cs
public class AppDataContext : DbContext
{
public AppDataContext(DbContextOptions<AppDataContext> contextOptions) : base(contextOptions) { }
public DbSet<CartItemEntity> CartItems { get; set; }
public DbSet<OrderEntity> Orders { get; set; }
public DbSet<UserEntity> Users{ get; set; }
}
DataConnectionContext.cs
public class DataConnectionContext
{
private readonly IConfiguration _configuration;
private readonly string _connectionString;
public DataConnectionContext(IConfiguration configuration)
{
_configuration = configuration;
_connectionString = _configuration.GetConnectionString("DefaultConnection");
}
public IDbConnection CreateConnection() => new SqlConnection(_connectionString);
}
Next is making a repository which holds the interface that has the create method.
public interface ICartItemRepository
{
//public Task<IEnumerable<CartItemEntity>> GetCartItems();
//public Task<CartItemEntity> GetCartItemEntity(Guid id);
public Task Createitem(CartItemEntity itemEntity);
}
Then a class that inherits the interface and calls the dependency constructors
public class CartItemRepository : ICartItemRepository
{
private readonly DataConnectionContext _connectionContext;
private readonly AppDataContext _appDataContext;
public CartItemRepository(DataConnectionContext connectionContext, AppDataContext appDataContext)
{
_connectionContext = connectionContext;
_appDataContext = appDataContext;
}
public async Task Createitem(CartItemEntity itemEntity)
{
_appDataContext.CartItems.Add(itemEntity);
await _appDataContext.SaveChangesAsync();
await _appDataContext.CartItems.ToListAsync();
}
}
Next is a command for POST request MediatR pattern
public record AddCartItemCommand(CartItemEntity cartItem) : IRequest<CartItemEntity>;
and a Handler which manages and returns the method createitem
public class AddItemsHandler : IRequestHandler<AddCartItemCommand, CartItemEntity>
{
private readonly ICartItemRepository _cartItemRepository;
public AddItemsHandler(ICartItemRepository cartItemRepository) => _cartItemRepository = cartItemRepository;
public async Task<CartItemEntity> Handle(AddCartItemCommand request, CancellationToken cancellationToken)
{
return await (Task<CartItemEntity>) _cartItemRepository.Createitem(request.cartItem);
}
}
and lastly, in the controller
[Route("api/cart-items")]
[ApiController]
public class CartItemsController : ControllerBase
{
private ISender _sender;
public CartItemsController(ISender sender) => _sender = sender;
[HttpPost]
public async Task<CartItemEntity> Post(CartItemEntity cartItemEntity)
{
return await _sender.Send(new AddCartItemCommand(cartItemEntity));
}
}
I tried modifying the return object in the handler but every time I change anything it always get the error squiggly line, so I just casted the (Task) after the await. Is this where I went wrong? Thank you for any answers.
The exception is clear. You can't cast a VoidTaskResult to Task<CartItemEntity>.
To solve the problem:
In ICartItemRepository, modify the return type for Createitem as Task<CartItemEntity>.
In CartItemRepository, implement Createitem method from the ICartItemRepository interface. Return the inserted itemEntity in the method.
Since you have implemented Task<CartItemEntity> Createitem(CartItemEntity itemEntity) in the ICartItemRepository interface, the casting to (Task<CartItemEntity>) is no longer needed, and suggested to be removed.
public interface ICartItemRepository
{
...
public Task<CartItemEntity> Createitem(CartItemEntity itemEntity);
}
public class CartItemRepository : ICartItemRepository
{
...
public async Task<CartItemEntity> Createitem(CartItemEntity itemEntity)
{
_appDataContext.CartItems.Add(itemEntity);
await _appDataContext.SaveChangesAsync();
return itemEntity;
}
}
public class AddItemsHandler : IRequestHandler<AddCartItemCommand, CartItemEntity>
{
...
public async Task<CartItemEntity> Handle(AddCartItemCommand request, CancellationToken cancellationToken)
{
return await _cartItemRepository.Createitem(request.cartItem);
}
}
Lets start with my architech. I will try to simplify my code as much as I can. If I totally mixed up, please warn me.
IUnitOfWork
public interface IUnitOfWork<T> : IDisposable
{
IEntityRepository<T> Repository { get; }
void Commit();
}
UnitOfWork
public class UnitOfWork<T> : IUnitOfWork<T>
{
private IDbConnection _Connection;
private IDbTransaction _Transaction;
public IRepository<T> Repository { get; private set; }
public UnitOfWork(IDbConnection Connection, IRepository<T> Repository)
{
_Connection = Connection;
this.Repository = Repository;
_Transaction = _Connection.BeginTransaction();
}
}
RepositoryBase
public abstract class RepositoryBase<T> : IRepository<T>
{
protected IDbTransaction Transaction;
protected IDbConnection Connection { get { return Transaction.Connection; } }
public RepositoryBase(IDbTransaction transaction)
{
Transaction = transaction;
}
}
TestDAL
public class TestDAL : RepositoryBase<Test>, ITestDAL
{
public DpTestDAL(IDbTransaction transaction) : base(transaction) {}
}
TestService (BLL)
public class TestService : ITestService
{
private IUnitOfWork<Test> uow;
public TestService(IUnitOfWork<Test> unitOfWork)
{
uow = unitOfWork;
}
public List<Test> GetAll()
{
return uow.Repository.GetAll().ToList();
}
}
And my autofac configurations.
builder.RegisterType<TestService>().As<ITestService>();
builder.RegisterType(typeof(OracleConnection)).As(typeof(IDbConnection)).InstancePerLifetimeScope();
builder.RegisterGeneric(typeof(RepositoryBase<>)).As(typeof(IRepository<>)).InstancePerLifetimeScope();
builder.RegisterGeneric(typeof(UnitOfWork<>)).As(typeof(IUnitOfWork<>)).InstancePerDependency();
//builder.RegisterType(typeof(OracleTransaction)).As(typeof(IDbTransaction)).InstancePerLifetimeScope();
I am newbie this kind of architect and try to something my self. Please tell me if there is something wrong or totally wrong.
My problem is, I need to pass the IDbTransaction to data acess classess contructor. When I do not register IDbTransaction interface, exception is "could not resolve parameter", when I try to register with OracleTransaction the exception is "OracleTransaction" do not has a public contructor. Where did I mixed up?
As the OracleTransaction doesn't have public constructor you can use IDbConnection to create one like below,
builder.Register(c =>
{
var conn = c.Resolve<IDbConnection>();
return conn.BeginTransaction(IsolationLevel.ReadCommitted);
});
The above is an example of how you can register it for your use case.
public class FooController : ApiController
{
private IDb db;
public FooController (IDb context)
{
db = context;
}
public void DoSomething(string value)
{
var output = new DoSomethingElse(value);
}
}
DoSomethingElse object is used by couple of methods in this class but it's not a requirement for all the methods. How do I register and resolve DoSomethingElse?
The problem as I understand it:
public class FooController : ApiController
{
private IDb db;
public FooController (IDb context)
{
db = context;
}
public void DoSomething(string value)
{
var output = new DoSomethingElse(value);
}
}
You don't want to instantiate the DoSomethingElse type everytime you instantiate the FooController. You also want to provide it with a value at run time.
So this calls for the Factory Pattern:
public interface IDoSomethingElseFactory
{
IDoSomethingElse Create(string value);
}
public class DoSomethingElseFactory : IDoSomethingElseFactory
{
public IDoSomethingElse Create(string value)
{
// Every call to this method will create a new instance
return new DoSomethingElse(value);
}
}
public class FooController : ApiController
{
private IDb db;
private readonly IDoSomethingElseFactory doSomethingElseFactory;
public FooController (
IDb context,
IDoSomethingElseFactory doSomethingElseFactory)
{
db = context;
this.doSomethingElseFactory = doSomethingElseFactory;
}
public void DoSomething(string value)
{
// this will be the point at which a brand new
// instance of `DoSomethingElse` will be created.
var output = doSomethingElseFactory.Create(value);
}
}
Then to register this:
builder.RegisterType<DoSomethingElseFactory>()
.As<IDoSomethingElseFactory>()
As an answer to my own question:
What would be the most elegant way to use Entity Framework with Generic Repository, in Service Stack, and to write Integration \ Unit Tests for service?
At the moment, this is how my structure looks like:
Generic repository layer:
public class GenericRepository<TEntity> where TEntity : class
{
internal DbContext Context;
//...
//CRUD Operations, etc.
}
Unit of work layer:
public class UnitOfWork : IDisposable
{
private readonly DbContext _context;
public UnitOfWork(DbContext ctx)
{
_context = ctx;
}
private bool _disposed;
private GenericRepository<User> _userRepository;
public GenericRepository<User> UserRepository
{
get { return _userRepository ?? (_userRepository = new GenericRepository<User>(_context)); }
}
//...
}
Business layer:
public class UserBusiness
{
public UnitOfWork UoW { get; set; }
public void AddUser(Models.User user)
{
//Map from domain model to entity model
var u = Mapper.Map<Models.User, DAL.Repository.User>(user);
UoW.UserRepository.Insert(u);
UoW.Save();
}
}
API project:
public class AppHost : AppHostBase
{
public AppHost() : base("Users Service", typeof(UsersService).Assembly) { }
//...
public override void Configure(Funq.Container container)
{
//...other configuration
//UoW registration
container.Register(c => new UnitOfWork(new DbContext("my-DB-connection"))).ReusedWithin(Funq.ReuseScope.Hierarchy);
//Business layer class registration
container.Register<UserBusiness>(c=>new UserBusiness {
UoW = c.Resolve<UnitOfWork>()
}).ReuseWithin(Funq.ReuseScope.Hierarchy);
}
}
public class UsersService : Service
{
public UserBusiness UB { get; set; }
public object Post(User u)
{
UB.AddUser(u);
//...
}
}
So when it comes to integration testing, I can just do something like this:
Declare _appHost
private ServiceStackHost _appHost;
And configure funq container like this:
public override void Configure(Funq.Container container)
{
//...create mocked context
var mockedContext = new Mock<IDbContext>();
mockedContext.Setup(x => x.Set<User>()).Returns(new List<User>
{
new User { ID = 1, FirstName = "John", LastName = "Doe" }
});
//(or use effort or any other way to create it)
container.Register(c => new UnitOfWork(mockedContext)).ReusedWithin(Funq.ReuseScope.Hierarchy);
}
And test as usual:
[Test]
public void Get_User_By_Id()
{
//...generate client instance (JsonServiceClient) etc.
var customer = client.Get(new GetCustomer { Id = 1 });
Assert.AreEqual("John", customer.FirstName);
///...
}
In addition to have all layers available for DI, and mocking, I also created IDbContext, IGenericRepository, IUnitOfWork, etc. interfaces.
I didn't include it here in order to keep this as simple as I could.
But I would like to hear if there's a better (more elegant way) to do it.
I have implemented my first Generic repository in MVC app. Works fine but how to put repositories in Transaction scope?
public interface IRepository<TEntity> where TEntity : class
{
List<TEntity> FetchAll();
IQueryable<TEntity> Query { get; }
void Add(TEntity entity);
void Delete(TEntity entity);
void Save();
}
public class Repository<T> : IRepository<T> where T : class
{
private readonly DataContext _db;
public Repository(DataContext db)
{
_db = db;
}
#region IRepository<T> Members
public IQueryable<T> Query
{
get { return _db.GetTable<T>(); }
}
public List<T> FetchAll()
{
return Query.ToList();
}
public void Add(T entity)
{
_db.GetTable<T>().InsertOnSubmit(entity);
}
public void Delete(T entity)
{
_db.GetTable<T>().DeleteOnSubmit(entity);
}
public void Save()
{
_db.SubmitChanges();
}
#endregion
}
private void RegisterDependencyResolver()
{
var kernel = new StandardKernel();
var connectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
kernel.Bind(typeof(DataContext)).ToMethod(context => new DataContext(connectionString));
kernel.Bind(typeof(IRepository<>)).To(typeof(Repository<>));
DependencyResolver.SetResolver(new NinjectDependencyResolver(kernel));
}
public class AdminController : Controller
{
private readonly IRepository<User> _userRepository;
private readonly IRepository<Order> _orderRepository;
public AdminController(IRepository<User> userRepository, IRepository<Order> orderRepository)
{
_userRepository = userRepository;
_orderRepository = orderRepository;
}
public ActionResult InsertUser(UserViewModel model)
{
//Skip Code
//Do not commit data to database if _orderRepository is failed to save data
_userRepository.Add(user);
_userRepository.Save();
//Skip Code
_orderRepository.Add(order);
_orderRepository.Save();
}
}
What would be best method to wrap repository code with Transaction scope in InsertUser action?
You are missing an abstraction here. You should place all your business logic inside command handlers and create a command handler decorator that implements transaction behavior. This article describes how to do this, but in short:
Define an ICommandHandler<TCommand> interface:
public interface ICommandHandler<TCommand>
{
void Handle(TCommand command);
}
Create commands that define the contract of a business operation. Commands are simply DTOs (with only data and no behavior). For instance:
public class ShipOrderCommand
{
public int OrderId { get; set; }
public ShippingInfo Info { get; set; }
}
Implement command handlers that will contain the business logic / behavior for those commands:
public class ShipOrderCommandHandler
: ICommandHandler<ShipOrderCommand>
{
private readonly IRepository<Order> repository;
public ShipOrderCommandHandler(
IRepository<Order> repository)
{
this.repository = repository;
}
public void Handle(ShipOrderCommand command)
{
// do some useful stuf with the command and repository.
}
}
Let your MVC Controllers depend on the ICommandHandler<T> abstraction:
public ShipOrderController : Controller
{
private readonly ICommandHandler<ShipOrderCommand> handler;
public ShipOrderController(
ICommandHandler<ShipOrderCommand> handler)
{
this.handler = handler;
}
public void Ship(int orderId, ShippingInfo info)
{
this.handler.Handle(new ShipOrderCommand
{
OrderId = orderId,
Info = info
});
}
}
Define a generic decorator that implements transaction logic:
public TransactionalCommandHandlerDecorator<TCommand>
: ICommandHandler<TCommand>
{
private ICommandHandler<TCommand> decoratedHandler;
public TransactionalCommandHandlerDecorator(
ICommandHandler<TCommand> decoratedHandler)
{
this.decoratedHandler = decoratedHandler;
}
public void Handle(TCommand command)
{
using (var scope = new TransactionScope())
{
this.decoratedHandler.Handle(command);
scope.Complete();
}
}
}
Ensure that each ShipOrderCommandHandler is decorated with a TransactionalCommandHandlerDecorator and injected into ShipOrderController. You can do this with your favorite DI container, or by hand:
protected override IController GetControllerInstance(
RequestContext requestContext, Type controllerType)
{
if (controllerType == typeof(ShipOrderController))
{
return new ShipOrderController(
new TransactionalCommandHandlerDecorator<ShipOrderCommand>(
new ShipOrderCommandHandler(
new OrderRepository())));
}
return base.GetControllerInstance(requestContext, controllerType);
}
With this in place you can run all your business logic inside a transaction, without the need for the business logic to be aware of that.
There's a pattern called Unit of work. Here's an explanation.