How inject depedency to CompositeControl using Nin

Question

How to inject dependency into CompositeControl?

I tried the following approach - MyServerControl's Calculate is still null.

Thanks!

public class MyServerControl : CompositeControl
{
    private TextBox TextBox1;
    private TextBox TextBox2;
    private Label Label1;

    [Inject] // **** This is null **** 
    public ICalculate Calculate { get; set; }

    protected override void CreateChildControls()
    {
        TextBox1 = new TextBox {ID = "TextBox1", Text = "1"};
        Controls.Add(TextBox1);

        TextBox2 = new TextBox {ID = "TextBox2", Text = "2"};
        Controls.Add(TextBox2);

        var button1 = new Button {ID = "Button1", Text = "Calculate"};
        button1.Click += button1_Click;
        Controls.Add(button1);

        Label1 = new Label {ID = "Label1"};
        Controls.Add(Label1);
    }

    private void button1_Click(object sender, EventArgs e)
    {
        int value1 = Int32.Parse(TextBox1.Text);
        int value2 = Int32.Parse(TextBox2.Text);

        Label1.Text = "Result:" + Calculate.Add(value1, value2);
    }
}

public interface ICalculate
{
    int Add(int x, int y);
}

public class Calculate : ICalculate
{
    public int Add(int x, int y)
    {
        return x + y;
    }
}

Default Ninject.Web.Common Bootstrapper from NuGet:

using System.Net.NetworkInformation;

[assembly: WebActivator.PreApplicationStartMethod(typeof(NinjectDemo.App_Start.NinjectWebCommon), "Start")]
[assembly: WebActivator.ApplicationShutdownMethodAttribute(typeof(NinjectDemo.App_Start.NinjectWebCommon), "Stop")]

namespace NinjectDemo.App_Start
{
    using System;
    using System.Web;

    using Microsoft.Web.Infrastructure.DynamicModuleHelper;

    using Ninject;
    using Ninject.Web.Common;

    public static class NinjectWebCommon 
    {
        private static readonly Bootstrapper bootstrapper = new Bootstrapper();

        /// <summary>
        /// Starts the application
        /// </summary>
        public static void Start() 
        {
            DynamicModuleUtility.RegisterModule(typeof(OnePerRequestHttpModule));
            DynamicModuleUtility.RegisterModule(typeof(NinjectHttpModule));
            bootstrapper.Initialize(CreateKernel);
        }

        /// <summary>
        /// Stops the application.
        /// </summary>
        public static void Stop()
        {
            bootstrapper.ShutDown();
        }

        /// <summary>
        /// Creates the kernel that will manage your application.
        /// </summary>
        /// <returns>The created kernel.</returns>
        private static IKernel CreateKernel()
        {
            IKernel kernel = new StandardKernel();
            kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel);
            kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>();

            RegisterServices(kernel);
            return kernel;
        }

        /// <summary>
        /// Load your modules or register your services here!
        /// </summary>
        /// <param name="kernel">The kernel.</param>
        private static void RegisterServices(IKernel kernel)
        {
            kernel.Bind<ICalculate>().To<Calculate>().InSingletonScope();
        }        
    }
}

Updated:

I'm not able to get instance to kernel in Page_Load. Am I missing something?

<my:MyServerControl ID="MyServerControl1" runat="server" />

public partial class Default : Page
{
    [Inject]
    public ICalculate _calculate { get; set; }

    protected void Page_Load(object sender, EventArgs e)
    {
        kernel.Inject(MyServerControl1); // kernel is not available
    }
}

Answer 1

Your Default page doesn't know about NinjectWebCommon class existence. It also cannot know about the kernel variable which is a NinjectWebCommon.CreateKernel() method's member. The simplest solution is the following:

public static class NinjectWebCommon 
{
    ...
    private static IKernel kernel;

    public static IKernel CreateKernel()
    {
        if(kernel != null)
            return kernel;

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

        RegisterServices(kernel);
        return kernel;
    }
    ...
}

public partial class Default : Page
{
    [Inject]
    public ICalculate _calculate { get; set; }

    protected void Page_Load(object sender, EventArgs e)
    {
        NinjectWebCommon.CreateKernel().Inject(MyServerControl1);
    }
}

The other way would be to use Ninject magic. Your application class would probably need to inherit from a class provided by Ninject. In MVC it's a NinjectHttpApplication class, which overrides the bootstrapper. Than you could probably go with Wiktor's answer.

Honestly I don't like that Ninject magic, as it sometimes doesn't work for me and than it's very hard to find out why. In my MVC application I ended up creating my own ConfrollerFactory, which injected the dependencies explicitly. It also may be a pain if you want to change your IOC container.

Answer 2

I think you could just use the feature that satisfies dependencies on an existing object. In this particular case, in any context your control is used, you just call

kernel.Inject( myControl );

where myControl is an existing instance of your composite control. This has to be called from the code behind, somewhere in the pipeline where the instance is already created. Page_Load would most probably be fine.

Edit: there are numerous ways to be able to resolve anywhere in your application. You could for example have a global service locator. But since you are using the Bootstrapper, you should be able to resolvd your kernel anywhere

 var kernel = (IKernel)Bootstrapper.Container;

Answer 3

you need to register your Ioc config, see example:

public static void RegisterIoc(HttpConfiguration config)
        {
            var kernel = new StandardKernel(); // Ninject IoC

            kernel.Bind<IMyService>().To<MyService>();

            // Tell WebApi how to use our Ninject IoC
            config.DependencyResolver = new NinjectDependencyResolver(kernel);
        }

public class NinjectDependencyResolver : NinjectDependencyScope, IDependencyResolver
    {
        private IKernel kernel;

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

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

public class NinjectDependencyScope : IDependencyScope
    {
        private IResolutionRoot resolver;

        internal NinjectDependencyScope(IResolutionRoot resolver)
        {
            Contract.Assert(resolver != null);

            this.resolver = resolver;
        }

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

            resolver = null;
        }

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

            return resolver.TryGet(serviceType);
        }

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

            return resolver.GetAll(serviceType);
        }
    }

Add this class in your App_start folder, and then write in Global.asax.cs:

// Tell WebApi to use our custom Ioc (Ninject)
            IocConfig.RegisterIoc(GlobalConfiguration.Configuration);