Re: Resolve dependencies in IHttpHandler, pattern recommendations?

[Alex Meyer-Gleaves]

Hi Andy,

What you have looks like it would work just fine, but you could refactor things a little and get support for per-request lifetime scopes. 

I would do this by registering the HTTP handler with the container and using the route handler to resolve an instance per request.

builder.Register(c => new MyServiceImpl())

.As<IMyService>()

.InstancePerHttpRequest();

builder.Register(c => new MyHandler(c.Resolve<IMyService>()))

.AsSelf()

.InstancePerHttpRequest();

Your route handler would grab the current request lifetime scope from the dependency resolver and resolve the HTTP handler from that.

public class MyRouteHandler : IRouteHandler

{

public IHttpHandler GetHttpHandler(RequestContext requestContext)

{

var lifetimeScope = AutofacDependencyResolver.Current.RequestLifetimeScope;

return lifetimeScope.Resolve<MyHandler>();

}

}

The actual HTTP handler can then have the dependent service injected into its constructor.

public class MyHandler : IHttpHandler

{

readonly IMyService _myService;

public MyHandler(IMyService myService)

{

_myService = myService;

}

public void ProcessRequest(HttpContext context)

{

_myService.DoStuff();

context.Response.Write("Hello, world!");

}

public bool IsReusable { get; private set; }

}

Now the handler and its dependencies will be cleaned up at the end of each request.

Cheers,

Alex.

On 31 August 2012 23:19, <andy.b...@gmail.com> wrote:

Hi

I'm currently using Autofac for MVC and WebApi, but would like to use the same container within a single IHttpHandler. What is the simplest and/or best pattern to use? I am currently using the following code outline.

public class MyHandler : IHttpHandler

{

    public void ProcessRequest(HttpContext context)

    {

        using (ILifetimeScope container = AutofacDependencyResolver.Current.ApplicationContainer.BeginLifetimeScope())

        {

            var myService = container.Resolve<IMyService>();

                

            // do work                

        }

    }

}

public class MyHandlerRoute : IRouteHandler

{

    public IHttpHandler GetHttpHandler(RequestContext requestContext)

    {

        return new MyHandler();

    }

}

RouteTable.Routes.Add(new Route(url, new MyHandlerRoute()));

var containerBuilder = new ContainerBuilder();

var assembly = typeof(AutofacConfig).Assembly;

containerBuilder.RegisterApiControllers(assembly);

containerBuilder.RegisterControllers(assembly);

containerBuilder.RegisterType<MyServiceImpl>().As<IMyService>();

var container = containerBuilder.Build();

DependencyResolver.SetResolver(new AutofacDependencyResolver(container));

GlobalConfiguration.Configuration.DependencyResolver = new AutofacWebApiDependencyResolver(container);

Cheers.

Andy

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