Question

This is my controller

 public class SuggestionController : ApiController
{
    public ISuggestionRepository Repository { get; private set; }

    public SuggestionController(ISuggestionRepository repository)
    {
        this.Repository = repository;
    }

    // to post suggestion
    [HttpPost]
    [ActionName("PostSuggestion")]
    public HttpResponseMessage PostSuggestion(Suggestion suggestion)
    {
        var answerCorrect = this.Repository.CreateSuggestion(suggestion);

        if (answerCorrect == true)
            return Request.CreateResponse(HttpStatusCode.OK);
        else
            return Request.CreateResponse(HttpStatusCode.Conflict);
    }
}

and this is my RegisterServices method in NinjectWebCommon.cs

private static void RegisterServices(IKernel kernel)
    {
        kernel.Bind<ICompetitionRepository>().To(typeof(CompetitionRepository))
            .WithConstructorArgument("serviceContext", new InMemoryDataContext<Competition>());

        kernel.Bind<ISubmissionRepository>().To(typeof(SubmissionRepository))
            .WithConstructorArgument("serviceContext", new InMemoryDataContext<Submission>());

        kernel.Bind<IUserRepository>().To(typeof(UserRepository))
            .WithConstructorArgument("serviceContext", new InMemoryDataContext<User>());

        kernel.Bind<ISuggestionRepository>().To(typeof(SuggestionRepository))
           .WithConstructorArgument("serviceContext", new InMemoryDataContext<Suggestion>());
    } 

But am getting an exception that my suggestion controller does not have a default constructor and its showing a 500 internal server when am hitting the controller from a client app

I know that we get the exception of controller not having default constructor if the ninject dependency is not working properly but the below is another controller i have implemeneted similar to suggestion controller and its working absolutely fine.

 public IUserRepository Repository { get; private set; }

    public SSOController(IUserRepository repository)
    {
        this.Repository = repository;
    }

    [HttpPost]
    [ActionName("PostUser")]
    public HttpResponseMessage PostUser([FromBody]string id)
    {
        var accessToken = id;
        var client = new FacebookClient(accessToken);
        dynamic result = client.Get("me", new { fields = "name,email" });
        string name = result.name;
        string email = result.email;


        var existingUser = this.Repository.FindByUserIdentity(name);

        if (existingUser == null)
        {
            var newUser = new User
            {
                Username = name,
                Email = email,

            };

            var success = this.Repository.CreateAccount(newUser);

            if (!success)
            {
                return Request.CreateResponse(HttpStatusCode.InternalServerError);
            }

            //return created status code as we created the user
            return Request.CreateResponse<User>(HttpStatusCode.Created, newUser);
        }

        return Request.CreateResponse(HttpStatusCode.OK);

    }

}

I have no idea where am going wrong. Please let me know if u have any suggestions.

EDIT:

my Global.asax

 public class WebApiApplication : System.Web.HttpApplication
{
    protected void Application_Start()
    {
        AreaRegistration.RegisterAllAreas();

        WebApiConfig.Register(GlobalConfiguration.Configuration);
        FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
        RouteConfig.RegisterRoutes(RouteTable.Routes);
        AuthConfig.RegisterAuth();

        GlobalConfiguration.Configuration.IncludeErrorDetailPolicy =
IncludeErrorDetailPolicy.Always;

    }

Dependency resolver am using

 // Provides a Ninject implementation of IDependencyScope
// which resolves services using the Ninject container.
public class NinjectDependencyScope : IDependencyScope
{
    IResolutionRoot resolver;

    public NinjectDependencyScope(IResolutionRoot resolver)
    {
        this.resolver = resolver;
    }

    public object GetService(Type serviceType)
    {
        if (resolver == null)
            throw new ObjectDisposedException("this", "This scope has been disposed");

        return resolver.TryGet(serviceType);
    }

    public System.Collections.Generic.IEnumerable<object> GetServices(Type serviceType)
    {
        if (resolver == null)
            throw new ObjectDisposedException("this", "This scope has been disposed");

        return resolver.GetAll(serviceType);
    }

    public void Dispose()
    {
        IDisposable disposable = resolver as IDisposable;
        if (disposable != null)
            disposable.Dispose();

        resolver = null;
    }
}

// This class is the resolver, but it is also the global scope
// so we derive from NinjectScope.
public class NinjectDependencyResolver : NinjectDependencyScope, IDependencyResolver
{
    IKernel kernel;

    public NinjectDependencyResolver(IKernel kernel)
        : base(kernel)
    {
        this.kernel = kernel;
    }

    public IDependencyScope BeginScope()
    {
        return new NinjectDependencyScope(kernel.BeginBlock());
    }
}

and calling it in CreateKernel() method in NinjectWebCommon

 private static IKernel CreateKernel()
    {
        var kernel = new StandardKernel();
        kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel);
        kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>();

        RegisterServices(kernel);

        // Install our Ninject-based IDependencyResolver into the Web API config
        GlobalConfiguration.Configuration.DependencyResolver = new NinjectDependencyResolver(kernel);

        return kernel;
    }

Suggestion Repository

 public class SuggestionRepository : Repository<Suggestion>, ISuggestionRepository
{
    public SuggestionRepository(IServiceContext<Suggestion> servicecontext)
        : base(servicecontext)
    { }

    public bool CreateSuggestion(Suggestion suggestion)
    {
        this.ServiceContext.Create(suggestion);
        this.ServiceContext.Save();

        return true;
    }
}

ISuggestionRepository

public interface ISuggestionRepository
{
    bool CreateSuggestion(Suggestion suggestion);

}

Repository

public abstract class Repository<T>
{
    public IServiceContext<T> ServiceContext { get; private set; }

    public Repository(IServiceContext<T> serviceContext)
    {
        this.ServiceContext = serviceContext;
    }
}

IserviceContext

 public interface IServiceContext<T>
{
    IQueryable<T> QueryableEntities { get; }

    void Create(T entity);

    void Update(T entity);

    void Delete(T entity);

    void Save();
}

Answer 1

Since you’re using WebApi, you will need to use the WebApi extension for Ninject. Unfortunately, the current Ninject.WebApi nuget package is out of date, and doesn’t work with the released version of WebApi.

Temporarily, until Remo gets around to updating Ninject.WebApi to the release version, you can use Ninject.WebApi-RC http://nuget.org/packages/Ninject.Web.WebApi-RC

http://www.eyecatch.no/blog/2012/06/using-ninject-with-webapi-rc/

EDIT:

To recap the information discussed in comments, Here are the recommendations:

1) Use Ninject.MVC3 and Ninject.Web.WebApi (but use Ninject.Web.WebApi-RC until the official is updated) as discussed above. Do not use a custom DependencyResolver, and let Ninject.Web.Mvc and .WebApi do their job.

2) Change your bindings to this:

kernel.Bind<ICompetitionRepository>().To<CompetitionRepository>();
... similar bindings

3) Add a generic binding for your ServiceContext

kernel.Bind(typeof(IServiceContext<>)).To(typeof(InMemoryDataContext<>));