Setup
I have an AutoMapperConfiguration static class that sets up the AutoMapper mappings:
static class AutoMapperConfiguration()
{
internal static void SetupMappings()
{
Mapper.CreateMap<long, Category>.ConvertUsing<IdToEntityConverter<Category>>();
}
}
where IdToEntityConverter<T> is a custom ITypeConverter that looks like this:
class IdToEntityConverter<T> : ITypeConverter<long, T> where T : Entity
{
private readonly IRepository _repo;
public IdToEntityConverter(IRepository repo)
{
_repo = repo;
}
public T Convert(ResolutionContext context)
{
return _repo.GetSingle<T>(context.SourceValue);
}
}
IdToEntityConverter takes an IRepository in its constructor in order to convert an ID back to the actual entity by hitting up the database. Notice how it doesn't have a default constructor.
In my ASP.NET's Global.asax, this is what I have for OnApplicationStarted() and CreateKernel():
protected override void OnApplicationStarted()
{
// stuff that's required by MVC
AreaRegistration.RegisterAllAreas();
RegisterRoutes(RouteTable.Routes);
// our setup stuff
AutoMapperConfiguration.SetupMappings();
}
protected override IKernel CreateKernel()
{
var kernel = new StandardKernel();
kernel.Bind<IRepository>().To<NHibRepository>();
return kernel;
}
So OnApplicationCreated() will call AutoMapperConfiguration.SetupMappings() to set up the mappings and CreateKernel() will bind an instance of NHibRepository to the IRepository interface.
Problem
Whenever I run this code and try to get AutoMapper to convert a category ID back to a category entity, I get an AutoMapperMappingException that says no default constructor exists on IdToEntityConverter.
Attempts
Added a default constructor to IdToEntityConverter. Now I get a NullReferenceException, which indicates to me that the injection isn't working.
Made the private _repo field into a public property and added the [Inject] attribute. Still getting NullReferenceException.
Added the [Inject] attribute on the constructor that takes an IRepository. Still getting NullReferenceException.
Thinking that perhaps Ninject can't intercept the AutoMapperConfiguration.SetupMappings() call in OnApplicationStarted(), I moved it to something that I know is injecting correctly, one of my controllers, like so:
public class RepositoryController : Controller
{
static RepositoryController()
{
AutoMapperConfiguration.SetupMappings();
}
}
Still getting NullReferenceException.
Question
My question is, how do I get Ninject to inject an IRepository into IdToEntityConverter?
#ozczecho's answer is spot-on, but I'm posting the Ninject version of the code because it has one little caveat that caught us for a while:
IKernel kernel = null; // Make sure your kernel is initialized here
Mapper.Initialize(map =>
{
map.ConstructServicesUsing(t => kernel.Get(t));
});
You can't just pass in kernel.Get to map.ConstructServicesUsing because that method has a params parameter in addition to the Type. But since params are optional, you can just create the lambda expression to generate an anonymous function to get you what you need.
You have to give AutoMapper access to the DI container. We use StructureMap, but I guess the below should work with any DI.
We use this (in one of our Bootstrapper tasks)...
private IContainer _container; //Structuremap container
Mapper.Initialize(map =>
{
map.ConstructServicesUsing(_container.GetInstance);
map.AddProfile<MyMapperProfile>();
}
Related
I have a custom SiteRole class that inherits RoleProvider. I inject the IUserService in the constructor in order to do a query to get all Roles.
It kept on throwing an error that the SiteRole class needed a parameterless constructor. So I ended up injecting the IUserService like this:
public SiteRole()
{
_userService = DependencyResolver.Current.GetService<IUserService>();
}
Inside the class I override the GetRolesForUser function
public override string[] GetRolesForUser(string nickname)
{
return new string[] { _userService.GetRoleForUser(nickname) };
}
The UserService calls this LINQ query in the UserRepository (This line throws System.InvalidOperationException: 'The operation cannot be completed because the DbContext has been disposed.')
public string GetRoleForUser(string nickname)
{
return DbContext.Users.Where(u => u.Nickname == nickname).FirstOrDefault().Role.Name;
}
Any hints on how I can resolve this? You cannot inject dependencies to RoleProvider via constructor so I have to use DependencyResolver.Current.GetService().
Looks like your SiteRole class has a longer lifetime than the injected IUserService. You should check if it's really the source of issue and tune lifetimes of registered services with use of your DI container API. Here are some links for different containers: Autofac, NInject, Unity, Simple injector.
And, probably, change your SiteRole type a bit — use a property to get alive UserService instead of field, with which the only instance is created at time of SiteRole instantiation.
public SiteRole()
{
// this field should be removed
// _userService = DependencyResolver.Current.GetService<IUserService>();
}
// this property should be used instead of field
private IUserService UserService
{
get { DependencyResolver.Current.GetService<IUserService>(); }
}
Or in modern syntax
private IUserService UserService => DependencyResolver.Current.GetService<IUserService>();
But be careful and check that you won't get uncontrolled count of UserService instances created, if it's for example configured as instance per call in your DI container.
I solved the problem by doing this:
virtual Owned<IUserService> ResolveUserService()
=> DependencyResolver.Current.GetService<Owned<IUserService>>();
And call the service in the GetRolesForUser Method with a Using statement:
public override string[] GetRolesForUser(string nickname)
{
using(var userService = ResolveUserService())
{
return new string[] {userService.Value.GetRoleForUser(nickname) };
}
}
On a sidenote, DbContext is constructed in the RepositoryBase. I'm using the Generic Repository Pattern for my project.
public abstract class RepositoryBase<T> where T : class
{
#region properties
private StoreEntities dataContext;
private readonly IDbSet<T> dbSet;
protected IDbFactory DbFactory
{
get;
private set;
}
protected StoreEntities DbContext
{
get { return dataContext ?? (dataContext = DbFactory.Init()); }
}
#endregion
protected RepositoryBase(IDbFactory dbFactory)
{
DbFactory = dbFactory;
dbSet = DbContext.Set<T>();
}
#region Implementation of defaults
public virtual void Add(T entity)...........
Thanks for the help!
the error info :
Mapper not initialized. Call Initialize with appropriate
configuration. If you are trying to use mapper instances through a
container or otherwise, make sure you do not have any calls to the
static Mapper.Map methods, and if you're using ProjectTo or
UseAsDataSource extension methods, make sure you pass in the
appropriate IConfigurationProvider instance. InnerException:
StackTrace: at AutoMapper.Mapper.get_Configuration()
the asp.net mvc5 controller code
public override ActionResult Kendo_Read(DataSourceRequest request, IQueryable<Activity> results)
{
var data = results.ProjectTo<ActivityViewModel>();
var rdata = data.ToDataSourceResult(request);
return Json(rdata);
}
AutoMapper Configure Code
public class CRMProfile : Profile
{
CreateMap<Activity, ActivityViewModel>();
}
public static class Configuration
{
public static MapperConfiguration MapperConfiguration()
{
return new MapperConfiguration(x =>
{
x.AddProfile(new CRMProfile());
}
}
}
Register Code
internal static MapperConfiguration MapperConfiguration { get; private set; }
public class MvcApplication : System.Web.HttpApplication
{
MapperConfiguration = Configuration.MapperConfiguration();
}
i home return data type is IQueryable in the controller,not List,
I See the Question and Issue in stackoverflow but could not solved my problem.
From AutoMapper's source code you can see that this exception will be thrown when configuration is not initialized at all:
public static IConfigurationProvider Configuration
{
get => _configuration ?? throw new InvalidOperationException(InvalidOperationMessage);
private set => _configuration = value;
}
Make sure that Mapper is correctly configured using static properties or correctly registered using IoC container if you are using that (please, refer to documentation for details). Are you perhaps missing the Mapper.Initialize() call?
I am not at all sure what the underlying problem is that is causing this exception.
I am using ASP.NET MVC, with Unity.Mvc, and Entity Framework 6. I have the following code to register my repositories:
public static void RegisterTypes(IUnityContainer container)
{
// NOTE: To load from web.config uncomment the line below. Make sure to add a Microsoft.Practices.Unity.Configuration to the using statements.
// container.LoadConfiguration();
// TODO: Register your types here
// container.RegisterType<IProductRepository, ProductRepository>();
container.RegisterType<IGenericRepository<Customer>, GenericRepository<Customer>>();
container.RegisterType<IGenericRepository<Product>, GenericRepository<Product>>();
container.RegisterType<IGenericRepository<Order>, GenericRepository<Order>>();
container.RegisterType<IGenericRepository<OrderItem>, GenericRepository<OrderItem>>();
container.RegisterType<IGenericRepository<Supplier>, GenericRepository<Supplier>>();
}
And then in a controller I have:
public class IndexController : Controller
{
public IndexController(IGenericRepository<Customer> testGenericRepository)
{
var result = testGenericRepository.SelectAll();
}
public ActionResult Index()
{
return View();
}
}
And the repository has the following code:
public class GenericRepository<T> : IGenericRepository<T>
where T : class
{
private readonly DbContext _dbContext;
private readonly IDbSet<T> _dbSet;
public GenericRepository(DbContext dbContext)
{
if (dbContext == null)
{
throw new ArgumentNullException(nameof(dbContext));
}
_dbContext = dbContext;
_dbSet = _dbContext.Set<T>();
}
public IEnumerable<T> SelectAll()
{
return _dbSet.AsEnumerable<T>();
}
}
The problem that I'm having is that if I have a breakpoint in the "RegisterTypes" method, I can see that the container is definitely getting all the repositories registered, but a breakpoint in the constructor of the repositories never gets hit.
So I think that the fact that the breakpoint does not get hit, and I have not registered a "System.Data.Common.DbConnection" means that the DbContext that the repository uses never gets set.
I can't find any useful information about how to use "System.Data.Common.DbConnection" with Unity and the DbContext from Entity Framework.
How do I resolve this?
You should add to your RegisterTypes how to build your DbContext, and probably with which lifetime.
If you have your own class (say CustomContext) inheriting from DbContext, register it. Supposing your default lifetime is adequate:
container.RegisterType<DBContext, CustomContext>();
If you use directly DbContext, instruct Unity which constructor it should use. By example, supposing your connection string is named appConnectionString:
container.RegisterType<DBContext>(
new InjectionConstructor("name=appConnectionString"));
We are trying to use Ninject within an Owin with WebAPI pipeline. We have everything setup according to this documentation, but we cannot get InRequestScope() to work.
Here's the significant part of the startup.cs
public class Startup
{
public void Configuration(IAppBuilder app)
{
HttpConfiguration config = new HttpConfiguration();
// Web API routes
config.MapHttpAttributeRoutes();
// Ninject Setup
app.UseNinjectMiddleware(NinjectConfig.CreateKernel);
app.UseNinjectWebApi(config);
}
}
NinjectConfig looks something like this:
public sealed class NinjectConfig
{
public static IKernel CreateKernel()
{
var kernel = new StandardKernel();
INinjectModule[] modules =
{
new ApplicationModule()
};
instance.Load(modules);
// Do we still need to do this wtih Owin?
instance.Bind<IHttpModule>().To<OnePerRequestHttpModule>();
}
}
Our ApplicationModule lives in a separate infrastructure project with access to all of our different layers, for handling DI & Mapping:
public class ApplicationModule: NinjectModule
{
public override void Load()
{
// IUnitOfWork / EF Setups
Bind<ApplicationContext>().ToSelf().InRequestScope();
Bind<IUnitOfWork>().ToMethod(ctx => ctx.Kernel.Get<ApplicationContext>()});
Bind<ApplicationContext>().ToMethod(ctx => ctx.Kernel.Get<ChromLimsContext>()}).WhenInjectedInto<IDal>();
// other bindings for dals and business objects, etc.
}
}
Then we have a couple interfaces:
public interface IUnitOfWork()
{
void SaveChanges();
Task SaveChangesAsync();
}
and
public interface IDal()
{
// Crud operations, Sync and Async
}
then our actual classes using these:
public class SomeBusinessObject
{
private IUnitOfWork _uow;
private IDal _someDal;
public SomeBusinessObject(IUnitOfWork uow, IDal someDal)
{
_uow = uow;
_someDal = someDal;
}
public Task<SomeResult> SaveSomething(Something something)
{
_someDal.Save(something);
_uow.SaveChanges();
}
}
Some Dal
public class SomeDal : IDal {
private ApplicationContext _applicationContext;
public SomeDal(ApplicationContext applicationContext)
{
_applicationContext = applicationContext;
}
public void Save(Something something)
{
_applicationContext.Somethings.Add(something);
}
}
Our EF DbContext
public class ApplicationContext : DbContext, IUnitOfWork
{
// EF DBSet Definitions
public void SaveChanges()
{
base.SaveChanges();
}
}
The expectation is that for every request, a single instance of ApplicationContext is created and injected into the business objects as an IUnitOfWork implementation and into the IDals as an ApplicationContext.
Instead what is happening is that a new instance of ApplicationContext is being created for every single class that uses it. If I switch the scope from InRequestScope to InSingletonScope, then (as expected) exactly 1 instance is created for the entire application, and injected properly into the specified classes. Since that works, I'm assuming this isn't a binding issue, but instead an issue with the InRequestScope extension.
The only issue I could find similar to what I'm experiencing is this one, but unfortunately the solution did not work. I'm already referencing all of the packages he specified in both the WebApi and Infrastructure projects, and I double checked to make sure they are being copied to the build directory.
What am I doing wrong?
Edit:
Some additional information. Looking at the Ninject source code in both Ninject.Web.WebApi.OwinHost and Ninject.Web.Common.OwinHost, it appears that the Owin Middleware adds the OwinWebApiRequestScopeProvider as the IWebApiRequestScopeProvider. This provider is then used in the InRequestScope() extension method to return a named scope called "Ninject_WebApiScope". This will be present until the target class that being injected into switches. The named scope then disappears, and a new scope is created. I think this may be what #BatteryBackupUnit was referring to in their comment, but I don't know how to correct it.
This thread is related to this issue...
https://github.com/ninject/Ninject.Web.WebApi/issues/17
I've found that behavior of InRequestScope seems to change depending on how you inject them. For example...
public ValuesController(IValuesProvider valuesProvider1, IValuesProvider valuesProvider2)
{
this.valuesProvider1 = valuesProvider1;
this.valuesProvider2 = valuesProvider2;
}
Ninject will create and inject the same instance of IValuesProvider. However if the method were written as...
/// <summary>
/// Initializes a new instance of the <see cref="ValuesController"/> class.
/// </summary>
/// <param name="valuesProvider">The values provider.</param>
public Values2Controller(IKernel kernel)
{
this.valuesProvider1 = kernel.Get<IValuesProvider>();
this.valuesProvider2 = kernel.Get<IValuesProvider>();
}
...this will create two new instances.
Based on the information in the link in #Mick's post I ended up adding my own extension method like this. I am not sure about the downsides.
public static class CustomRequestScope
{
public static Ninject.Syntax.IBindingNamedWithOrOnSyntax<T> InCustomRequestScope<T>(this Ninject.Syntax.IBindingInSyntax<T> syntax)
{
return syntax.InScope(ctx => HttpContext.Current.Handler == null ? null : HttpContext.Current.Request);
}
}
I do consider switching to another container because of this issue.
In trying to configure ServiceStack.net to use Ninject as its IOC, I am getting errors referring to various bindings not being defined. Primarily for ICache Client.
What specific bindings need to be created to use Ninject properly?
Currently have specified:
Bind<ISessionFactory>().To<SessionFactory>();//Is this correct/needed?
Note
I have created an IContainerAdapter as per the ServiceStack documention to implement the use of Ninject.
(Found here:ServiceStack IOC Docs)
Note 2
My apphost configure method looks like this:
public override void Configure(Funq.Container container)
{
IKernel kernel = new StandardKernel(new BindingModule());
container.Adapter = new NinjectContainerAdapter(kernel);
}
Note 3
I have registered the ICacheClient as follows:
Bind().To();
And I am now getting an error pointing to IRequest
Error activating IRequestLogger\nNo matching bindings are available, and the type is not self-bindable
Container Adapter
public class NinjectContainerAdapter : IContainerAdapter
{
private readonly IKernel _kernel;
public NinjectContainerAdapter(IKernel kernel)
{
this._kernel = kernel;
}
public T TryResolve<T>()
{
return this._kernel.Get<T>();
}
public T Resolve<T>()
{
return this._kernel.Get<T>();
}
}
Have you injected your Container adapter with:
container.Adapter = new NinjectIocAdapter(kernel);
If so, try also make your AppHost class internal if you haven't done so. There should only be 1 instance of AppHost and some IOC's like to create their own instance, wiping out all the configuration from the first one.
The behavior you're getting sounds like Ninject is complaining about unresolved dependencies. Make sure you get Ninject to return null with Unresolved dependencies by using kernal.TryGet<T> in your Container Adapter, e.g:
public T TryResolve<T>()
{
return this._kernel.TryGet<T>();
}
You need to write your own IContainerAdapter and then set Container.Adapter in your AppHost