I have the following code in my ASP.NET project
public sealed class IoC
{
private static readonly IDependencyResolver resolver =
Service.Get("IDependencyResolver") as IDependencyResolver;
static IoC()
{
}
private IoC()
{
}
public static IDependencyResolver Container
{
get
{
return resolver;
}
}
}
public static class Service
{
public static object Get(string serviceName)
{
// Code to create and return instance...
}
}
Is IoC.Container going to be thread safe?
Initialization of static fields is thread-safe: that is, the .NET runtime guarantees that your field will be initialized only once in the program, no matter how many threads access it and in what order.
As Andrey points out, the Service.Get method itself needs to be thread-safe.
IoC itself looks ok, but the whole structure will not be thread-safe if resolver is not thread safe. If you want to have resolver per thread you can use attribute [ThreadStatic]
Related
I am using ef core and I am trying to implement the repository pattern as part of best practices. But I am we bit confused on the context normally I would create the context in the and inject
HomeController(WarehouseDBContext _context)
I have created my unitOfWork Class as suggested by the docs here
https://learn.microsoft.com/en-us/aspnet/mvc/overview/older-versions/getting-started-with-ef-5-using-mvc-4/implementing-the-repository-and-unit-of-work-patterns-in-an-asp-net-mvc-application#creating-the-unit-of-work-class
However I am tad confused. It's expecting options here which is normally handled on the controller.
My UnitOfWork class
public class WarehouseUnitOfWork : IDisposable
{
private WarehouseDBContext context = new WarehouseDBContext();
private WarehouseRepository<StockItem> stockRepository;
public WarehouseRepository<StockItem> StockRepoistry
{
get
{
if (this.stockRepository == null)
{
this.stockRepository = new WarehouseRepository<StockItem>(context);
}
return stockRepository;
}
}
public void Save()
{
context.SaveChanges();
}
private bool disposed = false;
protected virtual void Dispose(bool disposing)
{
if (!this.disposed)
{
if (disposing)
{
context.Dispose();
}
}
this.disposed = true;
}
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
}
But here it is complain that it expect options which would I presume contain the connection string. I am trying to decouple my code from EF so that If I want to upgrade in the future will be easier. My WareshouseDBContext is describe below
As you can see it is expecting options. What should I pass through here?
namespace WareHouseDal.Dal {
public class WarehouseDBContext : IdentityDbContext<ApplicationUser> {
public WarehouseDBContext(DbContextOptions<WarehouseDBContext> options)
: base(options) {
}
public DbSet<WarehouseCrm> Warehouse { get; set; }
public DbSet<Company> Companies { get; set; }
}
}
When I used to create my context before I just used the singleton pattern of
private readonly WarehouseDBContext _context;
Is their something else I need to do to allow it to accept the creation of the context on the unit of work level.
Error being given is
You shouldn't create a DbContext manually. Why not injecting the DbContext in your UOW class? Then the DI will manage the life cycle of the db context. To be honest I am not a fan of adding a UOW wrapper around EF which already implements the UOW pattern.
I would recommend you to see both talks, it will change the way you structure apps forever:
https://www.youtube.com/watch?v=5OtUm1BLmG0&ab_channel=NDCConferences
https://www.youtube.com/watch?v=5kOzZz2vj2o&t=3s&ab_channel=NDCConferences
Another amazing talk about EF Core details: https://www.youtube.com/watch?v=zySHbwl5IeU&ab_channel=NDCConferences
If you want to stick with Repository pattern, please check Ardalis repository with a clear example: https://github.com/ardalis/CleanArchitecture
I agree Ardalis repository is a great tutorial/example, in case if anyone want a lite solution to implement the Repository and Unit of Work Patterns in EF 5/EF 6.
you may check out the below one, I tested it would work in EF Core 6
https://pradeepl.com/blog/repository-and-unit-of-work-pattern-asp-net-core-3-1/
I'm using SignalR 0.5.2 and I'm trying to get a DependencyResolver set up using Unity. I've written the simplest code I can. I have a hub that I'm trying to inject into which looks like this:
public class SimpleHub : Hub
{
private readonly ITestService _service;
public SimpleHub(ITestService service)
{
_service = service;
}
public void Update()
{
Clients.callback("Kevin");
}
}
and a DependencyResolver that looks like this:
public class UnityDependencyResolver : DefaultDependencyResolver
{
private readonly IUnityContainer _container;
public UnityDependencyResolver(IUnityContainer container)
{
_container = container;
}
public override object GetService(Type serviceType)
{
if (_container.IsRegistered(serviceType))
{
return _container.Resolve(serviceType);
}
return base.GetService(serviceType);
}
public override IEnumerable<object> GetServices(Type serviceType)
{
if (_container.IsRegistered(serviceType))
{
return _container.ResolveAll(serviceType);
}
return base.GetServices(serviceType);
}
}
I register the dependency resolver in Global.asax
protected void Application_Start()
{
IUnityContainer container = new UnityContainer();
InitializeContainer(container);
SignalR.IDependencyResolver resolver = new UnityDependencyResolver(container);
GlobalHost.DependencyResolver = resolver;
RouteTable.Routes.MapHubs();
// more MVC stuff here
}
where InitializeContainer register the ITestService in Unity
The resolver "works" in that it's getting called for all the SignalR types, and if I leave my hub with a default constructor it all gets loaded. However the resolver never gets asked to resolve the ITestService interface.
I've also tried passing the resolver to MapHubs, still no luck. I've also tried property injection using the [Dependency] attribute and that didn't work either.
Do I need to register the resolver with MVC as well? (I have tried that by implementing both IDependecyResolver interfaces but get an exception telling me the resolver doesn't implement IServiceLocator)
So I've sort of fixed this. I wondered if the fact that the Hub was registered with the signalr container and the interface was registered with the Unity container was causing the issue. So I registered the Hub with Unity and then everything works.
This sort of makes sense as there are two containers.
Is this the standard behaviour?
In case someone else is wondering... I found a good SPA example that uses
SignalR 1.0.1
Unity 3
A bunch of other frameworks
The interesting thing is the way he create the container, the dependencies and everything else. Worth checking it out.
In an effort to make my entities persistent ignorant and make my repositories testable, I've implemented a repository pattern like so:
public interface IJobRepository : IRepository<Job>
{
Job GetJobById(int jobId); //Special case where I'm eager loading other entities
void SaveJob(Job job, Job originalJob);
}
public class JobRepository : IJobRepository
{
private readonly IContext _context;
public JobRepository()
{
_context = new CustomObjectContext();
}
public JobRepository(UnitOfWork unitOfWork)
{
_context = unitOfWork.Context;
}
//Basic GetAll, GetById, Add and Delete methods from IRepository<T> Interface here
//omitted for brevity
public Job GetJobById(int jobId)
{
var job = _context.Jobs.Include("Company").Include("Location").
Include("PlantInfo").Where(j => j.Jobid == jobId).SingleOrDefault();
_context.DisposeContext();
return job;
}
public void SaveJob(Job job, Job originalJob)
{
if (job.Jobid > 0)
{
// Update
_context.Jobs.Attach(originalJob);
_context.PlantInfoes.Attach(originalJob.PlantInfo);
_context.Jobs.ApplyCurrentValues(job);
_context.PlantInfoes.ApplyCurrentValues(job.PlantInfo);
Note: ApplyCurrentValues is an extension method I'm using on the ObjectSet
}
else
{
// Create
_context.Jobs.AddObject(job);
}
_context.Save();
}
}
public class UnitOfWork
{
private readonly IContext _context;
public UnitOfWork()
{
_context = new CustomObjectContext();
}
public UnitOfWork(IContext context)
{
_context = context;
}
public string Save()
{
return _context.Save();
}
internal IContext Context
{
get { return _context; }
}
}
public interface IContext
{
IObjectSet<Job> Jobs { get; }
IObjectSet<Company> Companies { get; }
IObjectSet<Location> Locations { get; }
IObjectSet<PlantInfo> PlantInfoes { get; }
string Save();
}
My ObjectContext inherits from IContext...So my understanding is that I will only use the overloaded constructor on the repository to facilitate unit tests or to use it in the case that I want to use the same context (not desirable based on this post I found on SO "Entity Framework and Connection Pooling" -- Is this right?
Also, assuming the context only gets disposed when the repository is garbage collected, I have to dispose the context explicitly to avoid the "An entity object cannot be referenced by multiple instances of IEntityChangeTracker." exception when attaching the entity prior to a save.
That said, what is the best practice for managing the DataContext in a manner that keeps your entities persistent ignorant and repositories testable?
Note: This is an asp.net webapplication; UnitOfWork and IContext implementation was based on examples from "Programming Entity Framework", Second Edition by Julia Lerman Ch24.
Thanks in advance!
Firstly, I would ensure that whatever my "consumable" object is (either repository or unit of work, depending on your setup) implements IDisposable. When your consumbed object is disposed of, then you would dispose your underlying context.
For instance, if you're using your UnitOfWork as the consumable object (the one that gets created and called in your application), it would look something like:
public class UnitOfWork : IDisposable
{
// All the other stuff you had before plus:
public void Dispose ()
{
if (_context != null)
{
_context.Dispose ();
}
}
}
(Note: This can also be done on your repositories if they're the ones being consumed directly)
And then, you have a few options in your application. If you are going to use the UnitOfWork directly, you can use it like:
public void SomeMethodThatAccessesYourData ()
{
using (var unitOfWork = new UnitOfWork (/*Load in the context*/))
{
// Access your data here.
}
}
Or, in your Web Forms or MVC object you can use constructor injection and dispose of it when the Web Forms or MVC object is disposed of:
// If you're using MVC:
public class MyController : Controller
{
private UnitOfWork _unitOfWork;
public MyController (UnitOfWork unitOfWork)
{
_unitOfWork = unitOfWork;
}
public override Dispose (bool Disposing)
{
if (Disposing && _unitOfWork != null)
{
_unitOfWork.Dispose ();
}
}
}
The same idea stands for a web forms Page.
The main reason for using the constructor overload is for Inversion of Control (IOC). It helps with both unit testing and with production code when used with an IoC Container. WebForms doesn't lend itself well to IoC, but it is really easy with MVC.
Edit
I don't really see the connection with your repositories and the unit of work. Usually you access the repositories from a unit of work or, in other implementations, you request a unit of work from your target repository. In your implementation (which I understand is not your own) there seems to be no need for both.
Edit 2
If the UoW is overkill for your application, and you know you can use IoC to inject your IContext, and you don't have very many repositories, you can do something like:
public IRepository<T> : IDisposable { }
public IJobRepository : IRepository<Job> { /* All the stuff you put here */ }
public JobRepository : IJobRepository
{
private IContext _context;
...
public void Dispose ()
{
if (_context != null)
{
_context.Dispose ();
}
}
public JobRepository (IContext context)
{
_context = context;
}
}
Then, how you use it depends on your specific task. I'm not a fan of this direct use of IRepository, but this answer is getting too long.
I am using unity, entity framework 4 with POCO classes, repository pattern for DAL and services for Business Logic control.
I also want to use Unit of Work so I can package together CRUD operations which I perform on different services and then commit them all together.
My question is what would be the proper way to inject the Unit Of Work mechanism into my application using Microsoft Unity?
I understand that I can put the IUnitOfWork together with the repository on the constructor of the proper service and then if Unity mapping is specified it would auto initiate the proper instances, but this way I do not pass the global unit of work but rather create a new instance on each level, which can't be a smart way to do it (actually the repository is initiated even before the service).
What am I missing? (Attached is constructor code as I wrote it now of service and its repository).
U also understand that I can use Unity's ParameterOverrides method to take some global instance of Unit of Work (lets say from my aspx.cs file) and pass it into the service and then into the repository. But it seems a bit lame. Is this my only option?
Thanks
public class GenericRepository<T> : IUnitOfWorkRepository, IGenericRepository<T> where T : BaseEntity, IAggregateRoot
{
private IUnitOfWork _uow;
/// <summary>
/// Returns the active object context
/// </summary>
private ObjectContext ObjectContext
{
get
{
return ObjectContextManager.GetObjectContext();
}
}
public GenericRepository(IUnitOfWork uow)
{
_uow = uow;
}
//blahhhh...
public void Add(T entity)
{
_uow.RegisterNew(entity, this);
}
public void Delete(T entity)
{
_uow.RegisterRemoved(entity, this);
}
//.....blah blah....
public void PersistCreationOf(IAggregateRoot entity)
{
this.ObjectContext.AddObject(GetEntitySetName(), entity);
}
public void PersistUpdateOf(IAggregateRoot entity)
{
// Do nothing as EF tracks changes
}
public void PersistDeletionOf(IAggregateRoot entity)
{
this.ObjectContext.DeleteObject(entity);
}
}
public class CategoryRepository : GenericRepository<XComSolutions.FB.Domain.Model.Entities.Category>, ICategoryRepository
{
public CategoryRepository(IUnitOfWork uow)
: base(uow)
{ }
}
public class CategoryService : ICategoryService
{
public int myID {get; set;}
private ICategoryRepository _categoryRepository;
private IUnitOfWork _uow;
public CategoryService(ICategoryRepository categoryRepository,
IUnitOfWork uow)
{
_categoryRepository = categoryRepository;
_uow = uow;
}
public List<Category> GetAll()
{
return _categoryRepository.GetAll();
}
}
Define an IUnitOfWorkFactory and inject that in your services:
public class Service
{
private readonly IUnitOfWorkFactory factory;
public Service(IUnitOfWorkFactory factory)
{
this.factory = factory;
}
public void DoOperation()
{
using (UnitOfWork context = this.factory.CreateNew())
{
this.DoSomeStuff(context);
this.DoMoreStuff(context);
context.SubmitChanges();
}
}
}
What I think you need to do is to define unit of work factory. You register this factory with your DI container and you resolve for this factory every time you need your unit of work. Then you get unit of work from the factory, work with it and let it go. You often will see that you need your unit of work within a scope of single method or single class. This article discuss Unit of Work pattern in connection with Entity Framework: http://msdn.microsoft.com/en-us/magazine/dd882510.aspx
I'm trying to add logging with aspect orientated programming using castle windsor in plain asp.net, i.e. not MVC
I've added a class that implements the IInterceptor interface and an attribute that inherits from Attribute.
public class LogAttribute : Attribute
{
public Level LogLevel { get; set; }
public LogAttribute(Level level)
{
LogLevel = level;
}
}
public class LoggingInterceptor : IInterceptor
{
public void Intercept(IInvocation invocation)
{
MethodInfo mi = invocation.Method;
LogAttribute[] atts = (LogAttribute[])mi.GetCustomAttributes(typeof(LogAttribute), true);
// if method not marked with InternalUseRestricted attribute, then pass on call
if (atts.Length == 0)
{
invocation.Proceed();
}
else
{
ISeiLogger log = LoggerFactory.GetLogger(mi.DeclaringType.ToString());
//assume only one logging attribute
//log on entry
log.LogEnter(atts[0].LogLevel);
//allow code to continue
invocation.Proceed();
//log on exit
log.LogExit(atts[0].LogLevel);
}
}
}
Now in the global.asax.cs I've added the following:
public partial class Global : System.Web.HttpApplication, IoCProvider
{
private void InitializeIoC()
{
container = new WindsorContainer();
container.Install(new Sei.Aspect.AspectInstaller());
}
public IWindsorContainer Container
{
get { return container; }
}
private static Sei.Logging.ISeiLogger log;
private IWindsorContainer container;
public override void Init()
{
base.Init();
InitializeIoC();
}
and I've created an installer class:
public class AspectInstaller : IWindsorInstaller
{
public void Install(IWindsorContainer container, IConfigurationStore store)
{
//container.Register(AllTypes.FromAssembly(Assembly.GetExecutingAssembly()).BasedOn<IInterceptor>().Configure(component => component.LifeStyle.PerWebRequest));
container.Register(Component.For<IInterceptor>().ImplementedBy<LoggingInterceptor>().LifeStyle.PerWebRequest);
container.Register(Component.For<IInterceptor>().ImplementedBy<InternalUseRestrictedInterceptor>().LifeStyle.PerWebRequest);
container.Register(Component.For<IInterceptor>().ImplementedBy<CachingInterceptor>().LifeStyle.PerWebRequest);
}
}
I now want to add the attribute to some arbitary page's code behind class and some arbitary virtual method, as in
[Log(Level.Info)]
protected string Login(string username, string password)
{
DoSomething();
}
This obviously doesn't work. Do I need to change the way I'm instantiating the page (its a page's code-behind class) to use a container? Or is it the way I'm registering the interceptors? I want to be able to use the interceptors on any class going forward and not have to tell the container about each and every class that I have in my application.
Short answer: it's not possible.
Long answer: due to the way ASP.NET Web Forms works, it doesn't let anyone interfere with the page instantiation. Some claim that using a custom PageHandlerFactory lets you do IoC, but this only lets you set properties after the page has been instantiated, which is simply not enough for proxying.
So runtime proxy libraries such as DynamicProxy or LinFu can't do anything about this. But you may be able to use compile-time aspect weavers, such as PostSharp.
Alternatively, make your code-behind as slim as possible, deferring actual logic to Windsor-managed components.