Adding Unity to MVC WebApi app

Question

Hello all I've Added Unity to an MVC app. it seems that DI is working with the MVC Portion of the app but i cannot figure out why it wont work with the API part of the application.

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        config.MapHttpAttributeRoutes();

        config.Routes.MapHttpRoute(
            name:"DefaultApi",
            routeTemplate:"api/{controller}/{id}",
            defaults: new {id = RouteParameter.Optional}
        );

        config.Formatters.Add(new JsonMediaTypeFormatter());
        config.Formatters.JsonFormatter.SerializerSettings.ReferenceLoopHandling =
            Newtonsoft.Json.ReferenceLoopHandling.Ignore;
        config.Formatters.JsonFormatter.SerializerSettings.Formatting = Newtonsoft.Json.Formatting.None;
    }
}

public static class UnityMvcActivator
{
    /// <summary>
    /// Integrates Unity when the application starts.
    /// </summary>
    public static void Start(HttpConfiguration configuration) 
    {
        FilterProviders.Providers.Remove(FilterProviders.Providers.OfType<FilterAttributeFilterProvider>().First());
        FilterProviders.Providers.Add(new UnityFilterAttributeFilterProvider(UnityConfig.Container));

        DependencyResolver.SetResolver(new UnityDependencyResolver(UnityConfig.Container));

        // TODO: Uncomment if you want to use PerRequestLifetimeManager
        // Microsoft.Web.Infrastructure.DynamicModuleHelper.DynamicModuleUtility.RegisterModule(typeof(UnityPerRequestHttpModule));


    }

    /// <summary>
    /// Disposes the Unity container when the application is shut down.
    /// </summary>
    public static void Shutdown()
    {
        UnityConfig.Container.Dispose();
    }
}

    public static void RegisterRoutes(RouteCollection routes)
    {
        routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

        routes.MapRoute(
            name: "Default",
            url: "{controller}/{action}/{id}",
            defaults: new { controller = "Address", action = "Index", id = UrlParameter.Optional }
        );
    }

}

protected void Application_Start()
        {
            AreaRegistration.RegisterAllAreas();
            GlobalConfiguration.Configure(WebApiConfig.Register);
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            BundleConfig.RegisterBundles(BundleTable.Bundles);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            UnityMvcActivator.Start(GlobalConfiguration.Configuration);


        }

I am just trying to get a repository to work in the web api but i keep getting

An error occurred when trying to create a controller of type 'AddressSearchController'. Make sure that the controller has a parameterless public constructor.",

this error. I have seen a few posts about this. I have tried them and still cannot get this to work. Does anyone have any suggestions?

public class AddressSearchController:_SimpleController<Address>
    {
        public AddressSearchController(IRepository<Address> addressRepository) : base(addressRepository)
        {

        }

        [HttpPost]
        [Route("api/AddressSearch/Search")]
        public IHttpActionResult Search([FromBody] AddressSearchDto addressSearchDto)
        {
            var addresses = new List<Address>()
            {
                CreateAddress(1,"Main St", 123),
                CreateAddress(2,"Main St", 124),
                CreateAddress(3,"Main St", 125),
            };

            return Ok(addresses);
        }

        static Address CreateAddress(int id,string street, int houseNumber)
        {
            return new Address()
            {
                Id = id,
                StreetName = street,
                HouseNumber = houseNumber
            };

        }
    }

     public static void RegisterTypes(IUnityContainer container)
    {
        RegisterInstances(container);
    }

    private static void RegisterInstances(IUnityContainer container)
    {
        container.RegisterType<IAddressContext, AddressContext>();
        container.RegisterType(typeof(IRepository<>), typeof(Repository<>));

    }

using System;
using Address_Tracker.Data.Context;
using Address_Tracker.Data.Context.Interfaces;
using Address_Tracker.Data.Repositories;
using Unity;

namespace Address_Tracker
{
    /// <summary>
    /// Specifies the Unity configuration for the main container.
    /// </summary>
    public static class UnityConfig
    {
        #region Unity Container
        private static Lazy<IUnityContainer> container =
          new Lazy<IUnityContainer>(() =>
          {
              var container = new UnityContainer();
              RegisterTypes(container);
              return container;
          });

        /// <summary>
        /// Configured Unity Container.
        /// </summary>
        public static IUnityContainer Container => container.Value;
        #endregion

        /// <summary>
        /// Registers the type mappings with the Unity container.
        /// </summary>
        /// <param name="container">The unity container to configure.</param>
        /// <remarks>
        /// There is no need to register concrete types such as controllers or
        /// API controllers (unless you want to change the defaults), as Unity
        /// allows resolving a concrete type even if it was not previously
        /// registered.
        /// </remarks>
        public static void RegisterTypes(IUnityContainer container)
        {
            RegisterInstances(container);
        }

        private static void RegisterInstances(IUnityContainer container)
        {
            container.RegisterType<IAddressContext, AddressContext>();
            container.RegisterType(typeof(IRepository<>), typeof(Repository<>));

        }
    }
}

Sadique · Accepted Answer · 2018-03-31 19:23:01Z

1

Your AddressSearchController should have a default constructor, or if you have no default / parameterless constructor, then please pass interfaces instead of concrete classes in AddressSearchController.

I believe you may have such a scenario:

public class AddressSearchController : ApiController
{
    public AddressSearchController(SomeClassParameter obj)
    {  
        //some code 
    }
}

What you want actually is ether this:

public class AddressSearchController : ApiController 
{
    public AddressSearchController() // add default ctor
    {  
    }
    public AddressSearchController(SomeClassParameter obj)
    {  
        //some code 
    }
}

or this:

Register the interface ISomeClassParameter for type SomeClassParameter in Unity

protected void Application_Start()
{
    AreaRegistration.RegisterAllAreas();
    UnityConfig.RegisterComponents();                           // <----- Add this line
    GlobalConfiguration.Configure(WebApiConfig.Register);
    FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
    RouteConfig.RegisterRoutes(RouteTable.Routes);
    BundleConfig.RegisterBundles(BundleTable.Bundles);
}

Register component:

container.RegisterType<ISomeClassParameter , SomeClassParameter >();

and do constructor injection :

public class AddressSearchController : ApiController 
{
    public AddressSearchController(ISomeClassParameter obj)
    {  
        //some code 
    }
}

Also, make sure you have the WebApi version of Unity

I tried it out, it worked for me:

edited Mar 31, 2018 at 19:23

answered Mar 31, 2018 at 18:35

Sadique

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13 Comments

JamTay317 Over a year ago

I have added AddressSearchController above and I only have one parameter in it.

Sadique Over a year ago

Did you register IRepository to a concrete type?

Sadique Over a year ago

I mean does your container register your IRepsitory to some concrete implementation like this container.RegisterType<IRepository, SomeRepository >();?

Sadique Over a year ago

@JamTay317 - Also your Application_Start is missing the line UnityConfig.RegisterComponents();

JamTay317 Over a year ago

that is called in UnityMvcActivator.Start(GlobalConfiguration.Configuration);

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