.net code 128 barcode The float-based layout enforced by our custom Object template in .NET

Making Code 128 in .NET The float-based layout enforced by our custom Object template

Summary

write and one place we can use to affect our entire site. If we want to change our datetime picker widget, we can simply go to the one date-time template to easily change the look and feel of our site.

Summary

The MVC pattern reduces business logic clutter in a view. Unfortunately, views now bring their own complexities that must be handled. To manage that complexity and reduce the frequency of breakage, we examined how we can use strongly typed views and separated view models to increase the cohesion of our views. With the popularity of separated view models increasing, the concept of using templates to drive content from the metadata on these view models became possible. With separated view models, we can now keep the view concerns of our application isolated from our domain model. Now that you understand how views work, we ll explore the fundamentals of using controllers in chapter 4.

Understanding the controller anatomy Storyboarding an application Mapping the presentation model Using input from the browser Passing view metadata Testing the controller

The focus of the Model-View-Controller pattern is the controller. With this pattern, every request is handled by a controller and rendered by a view. Without the controller, presentation and business logic would move to the view, as we ve seen with Web Forms. With the ASP.NET MVC Framework, every request routes to a controller, which is simply a class that implements the IController interface. Microsoft provides the base class System.Web.Mvc.Controller to make creating a controller easy. Which controller base class you choose isn t crucial because most request processing goes into executing the ActionResult, which is the type that each action returns. An action is a method on the controller class that handles a particular request. This method can take zero or many parameters, but by the time the action method

finishes executing, there ought to be one or many objects ready to be sent to the view, and the name of the view should be selected if the view doesn t follow the convention of having the same name as the action. Beyond that, the developer is in complete control when implementing a controller and its actions. This chapter will explore controllers that use many actions and inherit from the System.Web.Mvc.Controller base class. 9 will cover advanced topics regarding controllers. Let s dive into controller anatomy.

At its most basic level, a controller is simply a class that implements the IController interface. But most of the time your controllers will inherit from the System.Web. Mvc.Controller class rather than directly implementing IController. Controller classes contain one or more methods that act as actions. An action method is used to serve a single HTTP request; each action can take zero or many parameters and usually returns an ActionResult. Parameters are passed to the action method using the model binding infrastructure. By making use of these binders to do the heavy lifting, the controller action is free to focus on controlling application logic rather than translating user input to concrete classes. A well-written action should have a clear purpose and a single responsibility. That responsibility is to accept input from the browser and coordinate the flow of the application. Along the way, the action should rely on application services to perform tasks such as executing business logic, performing data access, or file I/O. Listing 4.1 shows a simple controller with a single action. This is a trivial example we ll tackle more complex scenarios later.

using System.Web.Mvc; namespace MvcInAction.Controllers { public class SimpleController : Controller { public ActionResult Hello() { ViewData.Add("greeting", "Hello Readers!"); return View(); } } }

Creating an action begins by ensuring that the method is public and returns ActionResult. If the method isn t public, it won t be called. Once that s set up, we can push some objects into ViewData and call the View() method with the name of the view that should render. That s the meat and potatoes of what it means to be an action method. Now that we ve defined the makeup of a controller, we ll look at how a controller implements an application s storyboard.