Inject value into injected dependency

Question

I\'m having something like this:

class Root
{
    public Root(IDependency dep)
    {}
}
class Dependency:IDependency         


        

Answer 1

With Ninject 3 IParameters (ConstructorArgument is one of them) will now simply be "inherited" to child request when they have ShouldInherit == true (see here).

The solution for this question can now be as simple as:

IResolutionRoot.Get<Root>(new ConstructorArgument("val", 12, true));

where as the true in the ConstructorArguments constructor sets ShouldInherit to true. Also see here

Answer 2

The Parameters.ConstructorArgument in the context only goes one leve deep by default.

One way of passing parameters down multiple levels is by using a ContextParameter, but something then needs to grab that and say - and now we're going to use that as a ConstructorArgument in this case. One such construct is Providers. See this dojo page for details of Providers

So you can do:

    class DependencyProvider : SimpleProvider<Dependency>
    {
        protected override Dependency CreateInstance( IContext context )
        {
            return new Dependency( (int)context.ParentContext.Parameters.GetOne<ContextVariableParameter>( "masterVal" ).Value );
        }
    }

    public static void Main()
    {
        var module = new InlineModule(
            mod => mod.Bind<IDependency>().ToProvider( new DependencyProvider() )
        );

        var kernel = new StandardKernel( new[  ] {module} );

        Root root = kernel.Get<Root>( With.Parameters.ContextVariable( "masterVal", 12 ) ); 
    }

Or you can manage it as follows:

    class RootProvider : SimpleProvider<Root>
    {
        protected override Root CreateInstance( IContext context )
        {
            return new Root( context.Kernel.Get<Dependency>( With.Parameters.ConstructorArgument("val", ( int )context.Parameters.GetOne<ContextVariableParameter>("masterVal").Value )));
        }
    }

    public static void Main()
    {
        var module = new InlineModule(
            mod => mod.Bind<IDependency>().To<Dependency>(), // Optional if ImplictSelfBinding is on
            mod => mod.Bind<Root>().ToProvider( new RootProvider() )
        );

        var kernel = new StandardKernel( new[] {module} );

        Root root = kernel.Get<Root>( With.Parameters.ContextVariable( "masterVal", 12 ) ); 
    }

While you're thinking about this, consider the points I make in this point re separating the concerns if configuration from object binding in this response.