Ninject not injecting and throwing null reference exceptions

Ninject not injecting and throwing null reference exceptions - c#

I'm new to Ninject so I'm sure that it's something I'm doing wrong, I'm just not sure what. I'm using Ninject and Ninject.MVC3 in my MVC3 web application. Here's an example of what I'm trying to do.
I'm using the Repository pattern:
public interface IRepository<T>
{
T Get(object id);
IList<T> GetAll();
void Add(T value);
void Update(T value);
void Delete(T value);
}
For a concrete type:
public Customer
{
public int Id { get; set; }
public string Name { get; set; }
public string Address { get; set; }
public Customer()
{
}
}
Now I have 2 separate repositories, a cached version that needs injection to the database repository:
public CachedCustomerRepository : IRepository<Customer>
{
private IRepository<Customer> _repository;
public Customer Get(object id)
{
Customer cust = new Customer();
IList<Customer> custs = GetAll();
if (custs != null && custs.Count > 0)
cust = custs.FirstOrDefault(c => c.Id == int.Parse(id.ToString()));
return cust;
}
public IList<Customer> GetAll()
{
IList<Customer> custs = HttpRuntime.Cache["Customers"] as IList<Customer>;
if (custs == null)
{
custs = _repository.GetAll();
if (custs != null && custs.Count() > 0)
{
double timeout = 600000d;
HttpRuntime.Cache.Insert("Customers", custs, null, DateTime.UtcNow.AddMilliseconds(timeout), System.Web.Caching.Cache.NoSlidingExpiration);
}
else
{
throw new NullReferenceException();
}
}
return custs;
}
public void Add(Customer value)
{
throw new NotImplementedException();
}
public void Update(Customer value)
{
throw new NotImplementedException();
}
public void Delete(Customer value)
{
throw new NotImplementedException();
}
public CachedCustomerRepository()
{
}
[Inject]
public CachedCustomerRepository(IRepository<Customer> repository)
{
_repository = repository;
}
}
public class CustomerRepository : IRepository<Customer>
{
public Customer Get(object id)
{
Customer cust = new Customer();
IList<Customer> custs = GetAll();
if (custs != null && custs.Count > 0)
cust = custs.FirstOrDefault(c => c.Id == int.Parse(id.ToString()));
return cust;
}
public IList<Customer> GetAll()
{
//Customer retrieval code
}
public void Add(Customer value)
{
throw new NotImplementedException();
}
public void Update(Customer value)
{
throw new NotImplementedException();
}
public void Delete(Customer value)
{
throw new NotImplementedException();
}
public CachedCustomerRepository()
{
}
}
I set up a NinjectModule like this:
public class ServiceModule : NinjectModule
{
public override void Load()
{
Bind<IRepository<Customer>>().To<CustomerRepository>();
}
}
and I modified the NinjectMVC3.cs in the AppStart folder to get the module when creating the kernel:
private static IKernel CreateKernel()
{
var kernel = new StandardKernel(new ServiceModule());
RegisterServices(kernel);
return kernel;
}
In my controller I am using this:
public ViewResult Index()
{
IRepository<Customer> custRepo = new CachedCustomerRepository();
return View(custRepo.GetAll());
}
It blows up on the line _repository.GetAll() in my CachedCustomerRepository.
I've set a breakpoint to make sure that the CreateKernel() is executing and getting the bindings, which it is. I'm just not sure why the injection isn't happening. One other side note, I don't know if it's important or not, the IRepository, the Repositories and the concrete type are in a separate class library and is referenced in the mvc3 web app. Both the web app and the class library have a reference to Ninject and the web app also has a reference to Ninject.MVC3. The binding and kernel creation is all taking place in the Web App.

First, you're calling the wrong constructor in your controller. This parameterless constructor doesn't call anything else and that's why you're getting the null exception. Second, you want to refactor your controller so that there are no direct dependencies.
You'd want to do something like the following:
public class SomeController
{
private readonly IRepository<Customer> repo;
public SomeController(IRepository<Customer> repo)
{
this.repo = repo;
}
public ViewResult Index()
{
return View(this.repo.GetAll());
}
}
This way, Ninject resolves the dependency for you! Ninject's kernel will be asked to create a controller with IRepository<Customer> by MVC. Since Ninject has this "binding", it'll try to instantiate the CustomerRepository for you.
Also, why are you creating a "CachedRepository"? I really, really think you're prematurely optimizing this. Honestly, you only need the one CustomerRepository and you'd wire that up within the Ninject module.

Have you made the class in Global.asax inherit NinjectHttpApplication?

Make sure you're calling DependencyResolver.SetResolver(CreateKernel()); in order to tell MVC which resolver you're going to use. You might be calling it but I didn't see it in your post - otherwise your code looks fine.

To get the full benefit of using an IOC you should refactor the CachedCustomerRepository dependency from you controller class. You will need to add a new binding to the your Ninject module. This binding will need to use the context to determine if it is binding the 'IRepository' to a CachedCustomerRepository instance or to the MVC Controller instance. Once you have that factored out, then Ninject will create and manage the lifetimes of both objects.

The problem is that when you create the CachedCustomerRepository in your action method, you're just instantiating it yourself and you're not getting Ninject to instantiate it for you and subsequently inject it's dependencies.
What you should do is use constructor injection for the controller.
E.g.
public class MyController : Controller
{
public IRepository<Customer> CustomerRepo { get; protected set; }
public MyController(IRepository<Customer> customerRepo)
{
CustomerRepo = customerRepo;
}
public ViewResult Index()
{
return View(CustomerRepo.GetAll());
}
}
Your scenario is slightly confusing though, because you are injecting a IRepository<Customer> into a IRepository<Customer> that needs to be injected into MyController.

Related

Generic DI from interface not resolving in Startup

I have created a generic interface
public interface ISqlTradeDataRetriever<T> where T : class
{
Task<T> GetSingleDayForSymbolAsync(string symbol, string date);
Task<ICollection<T>> GetAllAsync(string symbol);
}
and an implementation of such
public class SqlCommodityDataRetriever: ISqlTradeDataRetriever<Commodity>
{
private readonly BatlGroupWebContext _context;
public SqlCommodityDataRetriever(BatlGroupWebContext context)
{
_context = context;
}
public Task<Commodity> GetSingleDayForSymbolAsync(string symbol, string date)
{
var data = _context.Commodities.FirstOrDefaultAsync(m => m.Symbol == symbol
&& m.TradeDate == Convert.ToDateTime(date));
return data;
}
public Task<ICollection<Commodity>> GetAllAsync(string symbol)
{
throw new NotImplementedException();
}
}
and in startup.cs of the web application
services.AddScoped<ISqlTradeDataRetriever<Commodity>, SqlCommodityDataRetriever>();
but when I try to access the page where I am using this implementation I get an unresolved DI error
Unable to resolve service for type 'Infrastructure.DataRetrievers.SqlCommodityDataRetriever' while attempting to activate 'BATLGroupApp.Pages.Commodity.TradeData.EditModel'.
The edit model is as follows
public class EditModel : PageModel
{
private readonly SqlCommodityDataRetriever _retriever;
public EditModel(SqlCommodityDataRetriever retriever)
{
_retriever = retriever;
}
[BindProperty]
public DomainClasses.Classes.Commodity Commodity { get; set; }
public string CommoditySymbol { get; set; }
public async Task<IActionResult> OnGetAsync([FromQuery]string symbol, [FromQuery]string date)
{
if (string.IsNullOrEmpty(symbol) || string.IsNullOrEmpty(date))
{
return NotFound();
}
Commodity = await _retriever.GetSingleDayForSymbolAsync(symbol, date);
if (Commodity == null)
{
return NotFound();
}
CommoditySymbol = Commodity.CommoditySymbol.Symbol;
return Page();
}
}
What am I doing wrong in terms of registering the DI for this OR is my implementation wrong?

The registration is fine in its current form.
services.AddScoped<ISqlTradeDataRetriever<Commodity>, SqlCommodityDataRetriever>();
The page model however expects the concrete SqlCommodityDataRetriever implementation while the container is only aware of its ISqlTradeDataRetriever<Commodity> abstraction.
Refactor the page model to match the registration
public class EditModel : PageModel {
private readonly ISqlTradeDataRetriever<Commodity> _retriever;
public EditModel(ISqlTradeDataRetriever<Commodity> retriever) {
_retriever = retriever;
}
//... omitted for brevity since nothing else needs to change
as the class should ideally be dependent on abstractions instead of concretions for a more SOLID design.

instantiates class using ninject ioc in .net

I am using Ninject to do some IoC in my ASP.NET MVC application.
I have an interface "IService.cs" :
public interface IService
{
string method();
}
I have the corresponding implementation "Service.cs" :
public class Service
{
string method()
{
return "result";
}
}
I have done the binding in another class heriting from NinjectModule :
public class MyNinjectModule : NinjectModule
{
public override void Load()
{
RegisterServices();
}
private void RegisterServices()
{
Kernel.Bind<IService>().To<Service>();
}
}
I have my class A which use this service :
public class A
{
private readonly IService _service;
private int i;
public A(IService service, int i)
{
this._service=service;
this.i=i;
}
}
The problem is that now, I don't know how to instantiate my class A in my application. This is where am I stuck, how can I call Ninject
to tell my app to go get the implementation of my interface:
var myClass=new A(????)

The main problem is that your Service class does not implement IService.
public class Service
{
string method()
{
return "result";
}
}
It should be
public class Service : IService
{
public string method()
{
return "result";
}
}
But as for instantiating a class, the best approach is to use a composition root to build an object graph. In MVC, that is best handled by implementing IControllerFactory.
public class NinjectControllerFactory : DefaultControllerFactory
{
private readonly IKernel kernel;
public NinjectControllerFactory(IKernel kernel)
{
this.kernel = kernel;
}
protected override IController GetControllerInstance(RequestContext requestContext, Type controllerType)
{
return controllerType == null
? null
: (IController)this.kernel.Get(controllerType);
}
}
Usage
using System;
using Ninject;
using DI;
using DI.Ninject;
using DI.Ninject.Modules;
internal class CompositionRoot
{
public static void Compose()
{
// Create the DI container
var container = new StandardKernel();
// Setup configuration of DI
container.Load(new MyNinjectModule());
// Register our ControllerFactory with MVC
ControllerBuilder.Current.SetControllerFactory(new NinjectControllerFactory(container));
}
}
In Application_Start, add:
CompositionRoot.Compose();
You will also need to create an interface for your class A and register it. An integer cannot be resolved automatically, you have to do that explicitly.
Kernel.Bind<IClassA>().To<A>()
.WithConstructorArgument("i", 12345);
And then you would add your dependency to a controller. Dependencies of dependencies are resolved automatically.
public class HomeController : Controller
{
private readonly IClassA classA;
public HomeController(IClassA classA)
{
if (classA == null)
throw new ArgumentNullException("classA");
this.classA = classA;
}
public ActionResult Index()
{
// Use this.classA here...
// IService will be automatically injected to it.
ViewBag.Message = "Modify this template to jump-start your ASP.NET MVC application.";
return View();
}
}

Cordinate between my repository classes and controller classes to be using the same Context object

I am working on an asp.net mvc web application. now i have created multiple repositories classes, for example i have the following abstract repository classes:-
public interface ISkillRepository : IDisposable
{//code goes here..
&
public interface IStaffRepository : IDisposable
{//code goes here
and the model Repositories:-
public class SkillRepository : ISkillRepository , IDisposable
{
private SkillManagementEntities context = new SkillManagementEntities();
//code goes here
&
public class StaffRepository : IStaffRepository , IDisposable
{
private SkillManagementEntities context = new SkillManagementEntities();
now inside y controller i am intializing and creating the repo as follow:-
public class SkillController : Controller
{
private ISkillRepository skillRepository;
public SkillController() : this(new SkillRepository()) {}
public SkillController(ISkillRepository repository)
{
skillRepository = repository;
}
but currently i got the following error inside my application:
The relationship between the two objects cannot be defined because they are attached to different ObjectContext objects.
and the problem is that i need to be passing the same context accross the repos and controllers. so can anyone adivce on this:-
how i can inside one model repo to reference another repo using the same context class. for example inside the Staff repositoryto referecne the skill repository?
how i can inside a controller class to refer multiple repos , but at the same time pass the same context object among them , so if i issue a save() it will wrap all the statements inside one transaction. for example insie my skillController to reference both the skill & staff repos using the same context object ?
Thanks
Edit
I have created the following Unit of work class:-
public class UnitOfWork : IDisposable
{
private SkillManagementEntities context = new SkillManagementEntities();
private SkillRepository skillRepository;
private StaffRepository staffRepository;
private SecurityRoleRepository securityroleRepository;
public SkillRepository SkillRepository
{
get
{
if (this.skillRepository == null)
{
this.skillRepository = new SkillRepository(context);
}
return skillRepository;
}
}
public StaffRepository StaffRepository
{
get
{
if (this.staffRepository == null)
{
this.staffRepository = new StaffRepository(context);
}
return staffRepository;
}
}
public SecurityRoleRepository SecurityRoleRepository
{
get
{
if (this.staffRepository == null)
{
this.staffRepository = new SecurityRoleRepository(context);
}
return securityroleRepository;
}
}
public async Task Save()
{
await context.SaveChangesAsync();
}
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);
}
}
}
and then inside my repo i did the following:-
public class SecurityRoleRepository : ISecurityRoleRepository , IDisposable
{
private SkillManagementEntities context;// = new SkillManagementEntities();
public SecurityRoleRepository(SkillManagementEntities context)
{
this.context = context;
and on the controller class i will be referencing the UnitOfWork as follow:-
public class SecurityRoleController : Controller
{
private UnitOfWork unitOfWork = new UnitOfWork();
public async Task<ActionResult> Index(string filter = null, int page = 1, int pageSize = 20, string sort = "Name", string sortdir = "ASC")
{
try
{
var records = new PagedList<SecurityRole>();
ViewBag.filter = filter;
records.Content = await unitOfWork.SecurityRoleRepository.GetSecurityRoleForGrid(filter, page, pageSize, sort, sortdir).ToListAsync();
now i am facing a problem is that how i can referecne a repo from another Repo ? for example how i can reference the Skill repo inside the SecurityRole repo ?
EDIT Final
i did the following steps:-
1. i install
Install-Package Ninject.MVC5
2. then i created the following dependency class:-
public class YourDependencyResolverClass : IDependencyResolver
{
private IKernel kernel;
public YourDependencyResolverClass()
{
kernel = new StandardKernel();
AddBindings();
}
public object GetService(Type serviceType)
{
return kernel.TryGet(serviceType);
}
public IEnumerable<object> GetServices(Type serviceType)
{
return kernel.GetAll(serviceType);
}
private void AddBindings()
{
kernel.Bind<ISkillRepository>().To<SkillRepository>();
kernel.Bind<IStaffRepository>().To<StaffRepository>();
kernel.Bind<ISecurityRoleRepository>().To<SecurityRoleRepository>();
kernel.Bind<ICustomerRepository>().To<CustomerRepository>();
kernel.Bind<ISkillVersionHistoryRepository>().To<SkillVersionHistoryRepository>();
}
}
}
3.now inside my SkillRepository class i will be referencing the StaffRepository as follow:-
public class SkillRepository : ISkillRepository , IDisposable
{
private SkillManagementEntities context ;
private IStaffRepository staffrepo = (IStaffRepository)DependencyResolver.Current.GetService(typeof(IStaffRepository));
public SkillRepository(SkillManagementEntities context)
{
this.context = context;
}
Finally inside my action method i will be calling the Uiteofwork class as follow:-
public class StaffController : Controller
{
//private SkillManagementEntities db = new SkillManagementEntities();
UnitOfWork unitofwork = new UnitOfWork();
public async Task<ActionResult> AutoComplete(string term)
{
var staff = await unitofwork.StaffRepository.GetAllActiveStaff(term).Select(a => new { label = a.SamAccUserName }).ToListAsync();
return Json(staff, JsonRequestBehavior.AllowGet);
and the unite of work class is :-
public class UnitOfWork : IDisposable
{
private SkillManagementEntities context = new SkillManagementEntities();
private SkillRepository skillRepository;
private StaffRepository staffRepository;
private SecurityRoleRepository securityroleRepository;
private CustomerRepository customerRepository;
private SkillVersionHistoryRepository SVH;
public SkillRepository SkillRepository
{
get
{
if (this.skillRepository == null)
{
this.skillRepository = new SkillRepository(context);
}
return skillRepository;
}
}
public StaffRepository StaffRepository
{
get
{
if (this.staffRepository == null)
{
this.staffRepository = new StaffRepository(context);
}
return staffRepository;
}
}
public CustomerRepository CustomerRepository
{
get
{
if (this.customerRepository == null)
{
this.customerRepository = new CustomerRepository(context);
}
return customerRepository;
}
}
public SecurityRoleRepository SecurityRoleRepository
{
get
{
if (this.securityroleRepository == null)
{
this.securityroleRepository = new SecurityRoleRepository(context);
}
return securityroleRepository;
}
}
public SkillVersionHistoryRepository SkillVersionHistoryRepository
{
get
{
if (this.SVH == null)
{
this.SVH = new SkillVersionHistoryRepository(context);
}
return SVH;
}
}
public async Task Save()
{
await context.SaveChangesAsync();
}
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);
}
}
So can you adivce if my approach of using unitefwork and DI will guarantee that all my statements will be warped inside a single DB transaction ? thnaks?

We handle this by sharing a context using a singleton that is scoped to the request using HttpContext:
public MyContext GetContext()
{
if (System.Web.HttpContext.Current.Items["MyScopedContext"] == null)
{
System.Web.HttpContext.Current.Items["MyScopedContext"] = new MyContext();
}
return (MyContext)System.Web.HttpContext.Current.Items["MyScopedContext"];
}
The context object (repository) itself essentially houses a Unit of Work. The code I added above just gives you a way to share a single repository across all code running within a request. If your repository classes are defined in the scope of a web application, you can just replace your direct instantiation of SkillManagementEntities() with a call to a GetContext() method.
On the other hand if your repositories are defined in a layer shared by heterogeneous applications, you may need to get your context from a factory object that you can inject as needed. Either way, creating a new context object per repository is what's causing your issue.

Not an answer: this "use DI" suggestion answers a bit different question - OP is looking for "unit-of-work" pattern - while basic case (lifetime of unit of work matches lifetime of request/controller) can easily be solved with any DI framework, managing multiple units of work or units of work with longer lifetime is much harder and dedicated "unit of work factory" (sample usage) is likely the solution.
Usually when you go that far with interfaces/repositories and constructor dependency injection you have some Dependency Injection framework. There is a good chance that one you are using already provides "per HTTP request" resolution or allows to easily add one.
I.e. if you using Unity there is PerRequestLifetime lifetime manager that makes all .Resolve calls for the same interface/object to return the same instance for given request. See more info in DI with Unity MSDN article.
Approximate sample:
container.RegisterType<ISkillRepository, SkillRepository>();
container.RegisterType<IOtherRepository, OtherRepository>();
container.RegisterType<TheContext, TheContext>(new PerRequestLifetime());
With such registration and assuming you've configured ASP.Net MVC to use Unity to resolve types when controller is created it will get necessary dependencies (new instances as registered with default lifetime), but both will share the same context (assuming each depends on TheContext class either via constructor or property injection).

How do I connect the various pieces of my Web API Castle Windsor DI code?

How do I connect the various pieces of my Web API Castle Windsor DI code so that the Controller's routing selects the correct interface implementation?
Note: After several false starts/dead ends and partial victories (here and here and here), I am going to bountify this ASAP for the maximum 500 points. But I'm only going to award a really good answer - IOW, one that is clear enough that I can understand it and "plug it in" to my project so that I can hook a given concrete class to a particular Controller.
Here goes nothing: I have a Web API ("MVC") project. Really, though, this server project has no "V" (View), so maybe a better acronym would be MRC (Model/Repository/Controller).
At any rate, I'm trying to add DI to it using Castle Windsor.
I grok, and dig, the concept of swapping out concrete classes via constructor interface args. Just how to implement this functionality, though,
has been a beast I've been wrestling with, and I'm quite bruised and bloody at present, with mussed-up hair and mud-encrusted nostrils to boot.
I have, I think, most of the code I need - to start with, anyway. With DI in mind, I've now got a "DIPlumbing" folder, and a "DIInstallers" folder.
The "DIPlumbing" folder contains two classes: WindsorCompositionRoot.cs, and WindsorControllerFactory.cs.
The "DIInstallers" folder has, for now, three files, namely ISomethingProvider.cs, SomethingProvider.cs, and SomethingProviderInstaller.cs
SomethingProviderInstaller seems to be key in connecting the interfaces/classes in DIInstallers to the stuff in the DIPlumbing folder.
(I have also modified Global.asax.cs to replace the default controller routing business with the Castle Windsor replacement).
But I'm confused as to what classes I should be placing in the DIInstallers folder. Are these supposed to take the place of my Repositories (which likewise have an interface and a concrete class that implements that interface for each model)? IOW, should I basically move my Repository code into the DIInstallers folder - and then get rid of the IRepository and Repository units?
This, of course, would cause necessary changes to be made in the Controller classes, which as of now reference Repository classes.
Or do the Repositories and DIInstallers classes coexist? If so, what is the connection/affiliation between the Controllers, Installers, and Repositories?
It seems the more I read up on DI and Castle Windsor, the more confused I get. I don't know if I'm too dense for it, or if I'm trying to make it harder than it is, or if conflicting styles of using/presenting it are the problem. The bottom line is: I'm stuck in quicksand and need Johnny Quest to extend a sturdy bamboo rod.
The best answer of all, perhaps, and probably too much to ask for, would be a visual representation of how all these components - Controllers, Models, Repositories, Installers, Global.asax.cs, composition roots, factories, providers, etc., relate to each other.
For purposes of "full disclosure," I will add what I hope are the key elements of my code below to show what I've got and how it (hopefully) connects to each other.
Composition Root:
public class WindsorCompositionRoot : IHttpControllerActivator
{
private readonly IWindsorContainer container;
public WindsorCompositionRoot(IWindsorContainer container)
{
this.container = container;
}
public IHttpController Create(
HttpRequestMessage request,
HttpControllerDescriptor controllerDescriptor,
Type controllerType)
{
var controller =
(IHttpController)this.container.Resolve(controllerType);
request.RegisterForDispose(
new Release(
() => this.container.Release(controller)));
return controller;
}
private class Release : IDisposable
{
private readonly Action release;
public Release(Action release)
{
this.release = release;
}
public void Dispose()
{
this.release();
}
}
}
Controller Factory:
public class WindsorControllerFactory : DefaultControllerFactory
{
private readonly IKernel kernel;
public WindsorControllerFactory(IKernel kernel)
{
this.kernel = kernel;
//According to my understanding of http://docs.castleproject.org/Windsor.Typed-Factory-Facility.ashx, I might need this:
kernel.AddFacility<TypedFactoryFacility>();
}
protected override IController GetControllerInstance(RequestContext requestContext, Type controllerType)
{
if (controllerType == null)
{
throw new HttpException(404, string.Format("The controller for path '{0}' could not be found.", requestContext.HttpContext.Request.Path));
}
return (IController)kernel.Resolve(controllerType);
}
public override void ReleaseController(IController controller)
{
kernel.ReleaseComponent(controller);
}
// Note: The "Something" below will hopefully eventually be "Departments" and then other classes now represented in Models and their corresponding Repositories and Controllers
ISomethingProvider:
public interface ISomethingProvider
{
// These are placeholder methods; I don't know which I will need yet...
//bool Authenticate(string username, string password, bool createPersistentCookie);
//void SignOut();
}
SomethingProvider:
public class SomethingProvider : ISomethingProvider
{
// TODO: Implement methods in ISomethingProvider, once they have been added
}
SomethingProviderInstaller:
public class SomethingProviderInstaller : IWindsorInstaller
{
public void Install(IWindsorContainer container, IConfigurationStore store)
{
container.Register(Classes.FromThisAssembly()
.BasedOn(typeof(ISomethingProvider))
.WithServiceAllInterfaces());
// From http://app-code.net/wordpress/?p=676; see also http://devlicio.us/blogs/krzysztof_kozmic/archive/2009/12/24/castle-typed-factory-facility-reborn.aspx
container.AddFacility<TypedFactoryFacility>();
container.Register(Component.For<IMyFirstFactory>().AsFactory());
}
}
Controller:
public class DepartmentsController : ApiController
{
private readonly IDepartmentRepository _deptsRepository;
public DepartmentsController(IDepartmentRepository deptsRepository)
{
if (deptsRepository == null)
{
throw new ArgumentNullException("deptsRepository is null");
}
_deptsRepository = deptsRepository;
}
public int GetCountOfDepartmentRecords()
{
return _deptsRepository.Get();
}
public IEnumerable<Department> GetBatchOfDepartmentsByStartingID(int ID, int CountToFetch)
{
return _deptsRepository.Get(ID, CountToFetch);
}
. . .
}
IRepository:
public interface IDepartmentRepository
{
int Get();
IEnumerable<Department> Get(int ID, int CountToFetch);
}
Repository:
public class DepartmentRepository : IDepartmentRepository
{
private readonly List<Department> departments = new List<Department>();
public DepartmentRepository()
{
using (var conn = new OleDbConnection(
#"Provider=Microsoft.ACE.OLEDB.12.0;[bla]"))
{
using (var cmd = conn.CreateCommand())
{
cmd.CommandText = "SELECT td_department_accounts.dept_no, IIF(ISNULL(t_accounts.name),'No Name provided',t_accounts.name) AS name FROM t_accounts INNER JOIN td_department_accounts ON t_accounts.account_no = td_department_accounts.account_no ORDER BY td_department_accounts.dept_no";
cmd.CommandType = CommandType.Text;
conn.Open();
int i = 1;
using (OleDbDataReader oleDbD8aReader = cmd.ExecuteReader())
{
while (oleDbD8aReader != null && oleDbD8aReader.Read())
{
int deptNum = oleDbD8aReader.GetInt16(0);
string deptName = oleDbD8aReader.GetString(1);
Add(new Department { Id = i, AccountId = deptNum, Name = deptName });
i++;
}
}
}
}
}
public int Get()
{
return departments.Count;
}
private Department Get(int ID) // called by Delete()
{
return departments.First(d => d.Id == ID);
}
public IEnumerable<Department> Get(int ID, int CountToFetch)
{
return departments.Where(i => i.Id > ID).Take(CountToFetch);
}
. . .
}
Global.asax.cs:
public class WebApiApplication : System.Web.HttpApplication
{
private static IWindsorContainer container;
protected void Application_Start()
{
AreaRegistration.RegisterAllAreas();
GlobalConfiguration.Configure(WebApiConfig.Register);
BootstrapContainer();
FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
RouteConfig.RegisterRoutes(RouteTable.Routes);
BundleConfig.RegisterBundles(BundleTable.Bundles);
}
private static void BootstrapContainer()
{
container = new WindsorContainer().Install(FromAssembly.This());
var controllerFactory = new WindsorControllerFactory(container.Kernel);
ControllerBuilder.Current.SetControllerFactory(controllerFactory);
GlobalConfiguration.Configuration.Services.Replace(
typeof(IHttpControllerActivator), new WindsorCompositionRoot(container));
}
protected void Application_End()
{
container.Dispose();
}
UPDATE
In trying to run the server, so that it could test it with Fiddler2 to see just what is being passed around, it failed on this line in WindsorControllerFactory:
public WindsorControllerFactory(IKernel kernel)
{
this.kernel = kernel;
kernel.AddFacility<TypedFactoryFacility>(); <-- throws exception here
}
...with "System.ArgumentException was unhandled by user code
HResult=-2147024809
Message=Facility of type 'Castle.Facilities.TypedFactory.TypedFactoryFacility' has already been registered with the container. Only one facility of a given type can exist in the container.
Source=Castle.Windsor
StackTrace:
at Castle.MicroKernel.DefaultKernel.AddFacility(String key, IFacility facility)
at Castle.MicroKernel.DefaultKernel.AddFacility(IFacility facility)
at Castle.MicroKernel.DefaultKernel.AddFacilityT
at HandheldServer.DIPlumbing.WindsorControllerFactory..ctor(IKernel kernel) in c:\HandheldServer\HandheldServer\DIPlumbing\WindsorControllerFactory.cs:line 28
at HandheldServer.WebApiApplication.BootstrapContainer() in c:\HandheldServer\HandheldServer\Global.asax.cs:line 69
at HandheldServer.WebApiApplication.Application_Start() in c:\HandheldServer\HandheldServer\Global.asax.cs:line 39"
UPDATE 2
In response to Cristiano's answer:
So are you saying I should add the following two files to my Installers folder (I do have a DIInstallers folder already)
PlatypusInstallerFactory.cs:
public class PlatypusInstallerFactory : InstallerFactory
{
public override IEnumerable<Type> Select(IEnumerable<Type> installerTypes)
{
var windsorInfrastructureInstaller = installerTypes.FirstOrDefault(it => it == typeof(WindsorInfrastructureInstaller));
var retVal = new List<Type>();
retVal.Add(windsorInfrastructureInstaller);
retVal.AddRange(installerTypes
.Where(it =>
typeof(IWindsorInstaller).IsAssignableFrom(it) &&
!retVal.Contains(it)
));
return retVal;
}
}
WindsorInfrastructureInstaller.cs:
public class WindsorInfrastructureInstaller : IWindsorInstaller
{
public void Install(IWindsorContainer container, IConfigurationStore store)
{
container.AddFacility<TypedFactoryFacility>();
}
}
In your global.asax you'll create&use you installer factory as following
var installerFactory = new PlatypusInstallerFactory();
container.Install(FromAssembly.This(installerFactory));
If yes, what will that do for me? Does the above automagically register my Controller and/or Repository classes?
UPDATE 3
I am now using a lot of code from [http://blog.kerbyyoung.com/2013/01/setting-up-castle-windsor-for-aspnet.html#comment-form]
The key parts are, I think:
global.asax.cs:
private static IWindsorContainer _container;
protected void Application_Start()
{
AreaRegistration.RegisterAllAreas();
WebApiConfig.Register(GlobalConfiguration.Configuration);
FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
RouteConfig.RegisterRoutes(RouteTable.Routes);
BundleConfig.RegisterBundles(BundleTable.Bundles);
ConfigureWindsor(GlobalConfiguration.Configuration);
}
public static void ConfigureWindsor(HttpConfiguration configuration)
{
_container = new WindsorContainer();
_container.Install(FromAssembly.This());
_container.Kernel.Resolver.AddSubResolver(new CollectionResolver(_container.Kernel, true));
var dependencyResolver = new WindsorDependencyResolver(_container);
configuration.DependencyResolver = dependencyResolver;
}
WindsorDependencyResolver.cs:
namespace HandheldServer
{
public class WindsorDependencyResolver : System.Web.Http.Dependencies.IDependencyResolver
{
private readonly IWindsorContainer _container;
public WindsorDependencyResolver(IWindsorContainer container)
{
_container = container;
}
public IDependencyScope BeginScope()
{
return new WindsorDependencyScope(_container);
}
public object GetService(Type serviceType)
{
if (!_container.Kernel.HasComponent(serviceType))
{
return null;
}
return this._container.Resolve(serviceType);
}
public IEnumerable<object> GetServices(Type serviceType)
{
if (!_container.Kernel.HasComponent(serviceType))
{
return new object[0];
}
return _container.ResolveAll(serviceType).Cast<object>();
}
public void Dispose()
{
_container.Dispose();
}
}
public class WindsorDependencyScope : IDependencyScope
{
private readonly IWindsorContainer _container;
private readonly IDisposable _scope;
public WindsorDependencyScope(IWindsorContainer container)
{
this._container = container;
this._scope = container.BeginScope();
}
public object GetService(Type serviceType)
{
if (_container.Kernel.HasComponent(serviceType))
{
return _container.Resolve(serviceType);
}
else
{
return null;
}
}
public IEnumerable<object> GetServices(Type serviceType)
{
return this._container.ResolveAll(serviceType).Cast<object>();
}
public void Dispose()
{
this._scope.Dispose();
}
}
public class ApiControllersInstaller : IWindsorInstaller
{
public void Install(Castle.Windsor.IWindsorContainer container, Castle.MicroKernel.SubSystems.Configuration.IConfigurationStore store)
{
container.Register(Classes.FromThisAssembly() // should it be Types instead of Classes?
.BasedOn<ApiController>()
.LifestylePerWebRequest());
}
}
// This idea from https://github.com/argeset/set-locale/blob/master/src/client/SetLocale.Client.Web/Configurations/IocConfig.cs
public class ServiceInstaller : IWindsorInstaller
{
public void Install(IWindsorContainer container, IConfigurationStore store)
{
container.Register(
Component.For<IDeliveryItemRepository>().ImplementedBy<DeliveryItemRepository>().LifestylePerWebRequest(),
Component.For<IDeliveryRepository>().ImplementedBy<DeliveryRepository>().LifestylePerWebRequest(),
Component.For<IDepartmentRepository>().ImplementedBy<DepartmentRepository>().LifestylePerWebRequest(),
Component.For<IExpenseRepository>().ImplementedBy<ExpenseRepository>().LifestylePerWebRequest(),
Component.For<IInventoryItemRepository>().ImplementedBy<InventoryItemRepository>().LifestylePerWebRequest(),
Component.For<IInventoryRepository>().ImplementedBy<InventoryRepository>().LifestylePerWebRequest(),
Component.For<IItemGroupRepository>().ImplementedBy<ItemGroupRepository>().LifestylePerWebRequest());
}
}
}
UPDATE 4
This question is probably too general for SO, so I posted it on "Programmers"
UPDATE 5
Note: According to "The DI Whisperer" (Mark Seemann), IDependencyResolver should not be used, because it lacks a Release method (p. 207 of his book)

You should not mix installation vs resolving.
IOW your should not have
kernel.AddFacility<TypedFactoryFacility>();
in the WindsorControllerFactory
But the generic container configuration such registering TypedFactoryFacility should be executed in an installer called as earlier as possible.
In order to drive installer execution, you should use an Installer factory
public class YourInstallerFactory : InstallerFactory
{
public override IEnumerable<Type> Select(IEnumerable<Type> installerTypes)
{
var windsorInfrastructureInstaller = installerTypes.FirstOrDefault(it => it == typeof(WindsorInfrastructureInstaller));
var retVal = new List<Type>();
retVal.Add(windsorInfrastructureInstaller);
retVal.AddRange(installerTypes
.Where(it =>
typeof(IWindsorInstaller).IsAssignableFrom(it) &&
!retVal.Contains(it)
));
return retVal;
}
}
Where windsorInfrastructureInstaller will be somenthing like this
public class WindsorInfrastructureInstaller : IWindsorInstaller
{
public void Install(IWindsorContainer container, IConfigurationStore store)
{
// Resolvers
//container.Kernel.Resolver.AddSubResolver(new ArrayResolver(container.Kernel));
// TypedFactoryFacility
container.AddFacility<TypedFactoryFacility>();
}
}
In your global.asax you'll create&use you installer factory as following
var installerFactory = new YourInstallerFactory();
container.Install(FromAssembly.This(installerFactory));
Your "FrontEnd"(for example the mvc/webapi) project has a folder containing all installers(WindsorInfrastructureInstaller will be one of those) and the installer factory as well or at least that's the way I'm use to organize my solution.

In answer to my own question, I would simply say: There are no shortcakes! Without stopping go or further ado, go here and get this book. Resign yourself to take the time necessary to read it carefully.
So I'm not the only one; here's a quote from Jeff Beck, who wrote that book's foreword: "Often those who start using DI quickly find themselves lost in a sea of confusion."

Don't want to repeat everything again, so just check out my answer on How do I get Web API / Castle Windsor to recognize a Controller?.
As another note - I would advise against doing anything in your repository constructors if you can help it. The reason I say this is that the constructors get called as Windsor is trying to instantiate the correct instance of your repository. What this means is that if any kind of error occurs, it happens as WebApi is trying to create the controller. This can make it a bit tricky to track down the problem sometimes, and also ends up hiding the real issues under tons of layers of exceptions.

Implementing Generic Repository and UnitOfWork

I have followed this tutorial.
I got to a stage of calling a repository using _unitOfWork.XYZRepository.Get(), now to take it further I want to write an interface for my UnitOfWork class and inject it to my controller.
I am not sure whether I need write interface for GenericRepository or UnitofWork class or both.
Can some one guide me in this as to what needs to be done to instantiate a repository with interface instead of private readonly UnitOfWork _unitOfWork = new UnitOfWork(); as shown in the link above.

Modify your repository constructor to accept a unit of work, via its interface:
public MyRepository(IUnitOfWork unitOfWork)
{
_unitOfWork = unitOfWork;
}
Then you instantiate your repository, passing the appropriate unit of work in via the constructor. Alternatively, wire-up your IoC container of choice and let it do the heavy lifting.
Here's a nice tutorial on using Castle Windsor with ASP.NET MVC.

I have used Autofac for this purpose. In my Global.asax.cs file
var builder = new ContainerBuilder();
builder.RegisterType<UnitOfWork>().As<IUnitOfWork>().InstancePerApiRequest();
builder.RegisterAssemblyTypes(typeof (LocationTypesRepository).Assembly).Where(
type => type.Name.EndsWith("Repository")).AsImplementedInterfaces();
and then in my controller
public class LocationTypesController : ApiController
{
private readonly ILocationRepository _locationRepository;
private readonly IUnitOfWork _unitOfWork;
private readonly IAuthenticatedUser _user;
public LocationTypesController(ILocationRepository locationRepository,
IUnitOfWork unitOfWork,
IAuthenticatedUser user)
{
if (locationRepository == null)
throw new ArgumentNullException("locationRepository");
if (unitOfWork == null)
throw new ArgumentNullException("unitOfWork");
if (user == null)
throw new ArgumentNullException("user");
_locationRepository = locationRepository;
_unitOfWork = unitOfWork;
_user = user;
}
public IEnumerable<LocationType> Get()
{
try
{
IEnumerable<Location> locations = _locationRepository.GetAllAuthorizedLocations(_user.UserName);
_unitOfWork.Commit();
return locations.Select(location => location.LocationType).Distinct().OrderBy(location => location.LocationTypeId);
}
catch (Exception)
{
throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.BadRequest));
}
}
Essentially leveraging a DI framework and placing the interfaces as parameters to your repositories (or in my case a WebApi controller)

Based on suggestions I have made following changes...
public interface IGenericRepository<T> where T : class
{
IQueryable<T> Get();
IQueryable<T> FindBy(Expression<Func<T, bool>> predicate);
void Insert(T entity);
void Delete(T entity);
void Update(T entity);
void Save();
T GetByID(Object id);
}
public class GenericRepository<C, T> : IGenericRepository<T>
where T : class
where C : EFDbContext, new()
{
private C _entities = new C();
public C Context
{
get { return _entities; }
set { _entities = value; }
}
public virtual IQueryable<T> Get()
{
IQueryable<T> query = _entities.Set<T>();
return query;
}
public virtual T GetByID(object id)
{
return Context.Set<T>().Find(id);
}
}
//NinjectControllerFactory
private void AddBindings()
{
_ninjectKernel.Bind<IGenericRepository<Product>>().To<GenericRepository<EFDbContext, Product>>();
}
//Controller
[Inject]
public IGenericRepository<Product> ProductRepo;
public ProductController(IGenericRepository<Product> ProductRepository )
{
ProductRepo= ProductRepository ;
}
//Inside Action
model.Products = ProductRepo.Get();
Everything works now... Thanks for the help...

Develop Reference

C# (C-Sharp) is a programming language developed by Microsoft that runs on the .NET Framework.

Ninject not injecting and throwing null reference exceptions - c#

Have you made the class in Global.asax inherit NinjectHttpApplication?

Make sure you're calling DependencyResolver.SetResolver(CreateKernel()); in order to tell MVC which resolver you're going to use. You might be calling it but I didn't see it in your post - otherwise your code looks fine.

Related

Generic DI from interface not resolving in Startup

instantiates class using ninject ioc in .net

Cordinate between my repository classes and controller classes to be using the same Context object

How do I connect the various pieces of my Web API Castle Windsor DI code?

Implementing Generic Repository and UnitOfWork

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