System.web.Mvc DependencyResolver not able to create object for generic classes

Question

I am trying to use dependencyinjection in Controller and using System.Web.MvcDependencyResolver.Current.GetService() for creating service instances in controller class.

This works fine when Service Interfaces are non generic as below

public interface IProfileManagementService
{
   IList<News> GetSavedSearchList(int userObjectId, ApplicationType applicationType,int? vendorUserObjectId);
}

and my dependency resolver syntax as below gives me instance of ProfileManagementService

DependencyResolver.Current.GetService<IProfileManagementService>();

But If I create any generic service interface as below,

public interface ICommonProfileManagementService<T>
{
   IList<T> GetSavedSearchList(int userObjectId, ApplicationType applicationType,int? vendorUserObjectId);
}

But I get a null (CommonProfileManagementService objects are not created) for below code

DependencyResolver.Current.GetService<ICommonProfileManagementService<News>>();

Please Suggest some alternate ways of passing

IService<T>

instead of

IService

to DependencyResolver.Current.GetService()

What is your current Resolver? How do you actually register the implementation of the interface? — haim770
– haim770, Commented Jun 23, 2014 at 13:22

Mike Dymond · Accepted Answer · 2014-06-23 12:41:25Z

3

Here is the full code including the syntax needed to return a generic from DependencyResolver.

using Microsoft.Practices.Unity;
using System;
using System.Collections.Generic;
using System.Web.Mvc;
using Microsoft.Practices.Unity.Mvc;

namespace ConsoleApplication2
{
    class Program
    {
        public interface IService<T>
        {
            List<T> GetService();
        }

        public class Service<T> : IService<T>
        {
            public List<T> GetService()
            {
                return new List<T>();
            }
        }

        static void Main(string[] args)
        {
            var container = new UnityContainer();

            container.RegisterType(typeof(IService<>), typeof(Service<>));

            DependencyResolver.SetResolver(new UnityDependencyResolver(container));

            var service = DependencyResolver.Current.GetService(typeof(IService<string>));

            Console.WriteLine(service.ToString());

            Console.ReadKey();
        }
    }
}

edited Jun 23, 2014 at 12:41

answered Jun 20, 2014 at 15:21

Mike Dymond

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5 Comments

aditi Over a year ago

I tried this and it says interface name is not valid at this point

Mike Dymond Over a year ago

Where are you configuring your DI container?

Mike Dymond Over a year ago

Also, when you say, 'it says' do you mean that Visual Studio is reporting this error and hence not allowing you to compile. Or is that a run time error?

aditi Over a year ago

With the syntax it throws compile time error.Also I didnt configure any DI container. . DependencyResolver has defined an extension method GetService () that allows to pass interface name only.but it can not accept T along with the interface. Do I need to configure DI container and initialize that in appstart

Mike Dymond Over a year ago

Sorry, I meant that you should replace T with the actual type that you want to create the generic for. However you also need to implement a container and register that with DependencyResolver otherwise it will always return null. I will create a sample app and post the code here.

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