AMS304: Introduction to the ASP.NET Model View Controller (MVC) Framework Scott Hanselman Eilon Lipton Microsoft Microsoft

INTRO MVC

Goodness Maintain Clean Separation of Concerns ● Easy Testing ● Red/Green TDD ● Highly maintainable applications by default Extensible and Pluggable ● Support replacing any component of the system

Goodness Enable clean URLs and HTML ● SEO and REST friendly URL structures Great integration within ASP.NET ● Support both static and dynamic languages

What’s the Point? This is not Web Forms 4.0 ● It’s about alternatives. Car vs. Motorcycle. Simple or as complex as you like ● Extend it, add IOC. Or not. If the shoe pinches, don’t wear it. Fundamental ● Part of System.Web and isn’t going anywhere. Plays Well With Others ● Feel free to use NHibernate for Models, Brail for Views and Whatever for Controllers. Be Happy.

MVC Model ControllerView

A Little More Detail Model Controller View Browser requests /Products/ Route is determined Controller is activated Method on Controller is invoke Controller does some stuff Renders View, passing in custom ViewData URLs are rendered, pointing to other Controllers

Even More Detail – Request Flow You can futz at each step in the process Request URL Routing Route Route Handler Http Handler Controller View Factory View Response

Demo – Hello MVC World Don’t fall asleep, it’ll be worth it.

HOW IT WORKS MVC

Basic Controller Handling Scenarios, Goals and Design ● URLs route to controller “actions”, not pages – mark actions in Controller. ● Controller executes logic, chooses view. [ControllerAction] public void ShowPost(int id) { Post p = PostRepository.GetPostById(id); if (p != null) { RenderView("showpost", p); } else { RenderView("nosuchpost", id); }

Basic Views Scenarios, Goals and Design: ● Are for rendering/output. Pre-defined and extensible rendering helpers ● Can use.ASPX,.ASCX,.MASTER, etc. ● Can replace with other view technologies: Template engines (NVelocity, Brail, …). Output formats (images, RSS, JSON, …). Mock out for testing. ● Controller sets data on the View Loosely typed or strongly typed data

URL Routing – Pretty URIs Developers adds Routes to a global RouteTable Mapping creates a RouteData - a bag of key/values protected void Application_Start(object sender, EventArgs e) { RouteTable.Routes.Add(new Route { Url = "Blog/bydate/[year]/[month]/[day]", Defaults = new { controller="blog", action="showposts" }, Validation = new { day }); RouteTable.Routes.Add(new Route { Url = "[controller]/[action]/[id]", RouteHandler = typeof(MvcRouteHandler) }); }

Demo – Routing The route less travelled…

HOW TO TEST IT MVC

Interfaces and TDD Mockable Intrinsics ● IHttpContext, IHttpResponse, IHttpRequest Extensibility ● IController ● IControllerFactory ● IRouteHandler ● IView ● IViewFactory

Testing Controller Actions No requirement to mock out full ASP.NET runtime. [TestMethod] public void ShowPostsDisplayPostView() { TestPostRepository repository = new TestPostRepository(); TestViewFactory viewFactory = new TestViewFactory(); BlogController controller = new BlogController(…); controller.ShowPost(2); Assert.AreEqual("showpost", viewFactory.LastRequestedView); Assert.IsTrue(repository.GetPostByIdWasCalled); Assert.AreEqual(2, repository.LastRequestedPostId); }

Controller Factory Scenarios, Goals and Design: ● Hook creation of controller instance Dependency Injection. Object Interception. public interface IControllerFactory { IController CreateController(IHttpContext context, RouteData routeData, Type controllerType); } protected void Application_Start(object s, EventArgs e) { ControllerBuilder.Current.SetDefaultControllerFactory( typeof(MyControllerFactory)); }

View Factory Scenarios, Goals and Design: ● Mock out views for testing ● Replace ASPX with other technologies public interface IViewFactory { IView CreateView(IHttpContext context, RouteData routeData, string viewName, string layoutName, object viewData); } Inside controller class: ViewFactory = new XmlViewFactory(...); RenderView("foo", myData);

Demo – TDD Wasn’t this demo technically supposed to be first?

Demo – Dynamic Data Controls Not DDE. Scared you, didn’t I?

Demo – ImageGen It’s your thing. Do what you wanna do.

Demo – Ruby View Engine & Python Controller It’s a kinder, gentler Microsoft. No seriously. Hug?

Demo – XML-RPC SOAP is for dorks.

Conclusion This is not Web Forms 4.0 ● It’s about alternatives. Car vs. Motorcycle. Simple or as complex as you like ● Extend it, add IOC. Or not. If the shoe pinches, don’t wear it. Fundamental ● Part of System.Web and isn’t going anywhere. Plays Well With Others ● Feel free to use NHibernate for Models, Brail for Views and VB for Controllers. Be Happy.

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