Ninject InSingletonScope with Web Api RC

Question

I\'m having some difficulty using Ninject\'s InSingletonScope binding with Web Api RC. No matter how I create my binding, it looks like perhaps Web Api is handling scope/li

Answer 1

@Remo Gloor When I run your code in InMemoryHost of WebAPI and run Integration tests everything works fine and I do have singleton. If I run WebAPI solution inside VS Cassini web server first run is successful and when I click refresh I receive exception : Error loading Ninject component ICache No such component has been registered in the kernel's component container.

If I return old code with BeginBlock it works in Cassini but IsSingleton not working anymore in integration tests.

Answer 2

use

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

and don't dispose the kernel in the NinjectDependencyScope

Answer 3

Instead of not disposing the kernel (which will not call the internal dispose) you can simply implement your own singleton:

public static class NinjectSingletonExtension
{
    public static CustomSingletonKernelModel<T> SingletonBind<T>(this IKernel i_KernelInstance)
    {
        return new CustomSingletonKernelModel<T>(i_KernelInstance);
    }
}

public class CustomSingletonKernelModel<T>
{
    private const string k_ConstantInjectionName = "Implementation";
    private readonly IKernel _kernel;
    private T _concreteInstance;


    public CustomSingletonKernelModel(IKernel i_KernelInstance)
    {
        this._kernel = i_KernelInstance;
    }

    public IBindingInNamedWithOrOnSyntax<T> To<TImplement>(TImplement i_Constant = null) where TImplement : class, T
    {
        _kernel.Bind<T>().To<TImplement>().Named(k_ConstantInjectionName);
        var toReturn =
            _kernel.Bind<T>().ToMethod(x =>
                                       {
                                           if (i_Constant != null)
                                           {
                                               return i_Constant;
                                           }

                                           if (_concreteInstance == null)
                                           {
                                               _concreteInstance = _kernel.Get<T>(k_ConstantInjectionName);
                                           }

                                           return _concreteInstance;
                                       }).When(x => true);

        return toReturn;
    }
}

And then simply use:

i_Kernel.SingletonBind<T>().To<TImplement>();

Rather then

i_Kernel.Bind<T>().To<TImplement>().InSingletonScope();

note: although it is only matters for the first request, this implementation is not thread safe.