http://localhost:1042/Home/About in Visual C#

Printer USS Code 39 in Visual C# http://localhost:1042/Home/About

The http://localhost:1042 part of the URL is a Web server that is built into VS and runs the Web application without needing a Web server such as Internet Information Server (IIS) The number 1042 is a random port number generated by the Web server, and your port number is likely to be different

You can change your VS Web server s port number If you open your project s property page by right-mouse clicking on the project in Solution Explorer and select Properties, then select the Web tab on the left, under Servers, you can specify a specific port or make other Web server choices

For ASPNET MVC, the important part of the URL is /Home/About Home is the name of the Controller, and ASPNET MVC appends Controller to the URL name, looking for the HomeController class, shown in Listing 9-1, physically located in the Controller folder, which is why it s important to ensure you create files in the proper locations About is an action, which corresponds to the About method shown in Listing 9-1 Similar to the About method, the Index action is run through the following URL:

In a later section of this chapter, you ll learn how ASPNET MVC performs routing, which maps URLs to Controllers Both the Index and About actions in Listing 9-1 invoke a method named View This is a convention for invoking a View with the same name as the action method For example, calling View in the Index action will show a View named Index, and the call to View in the About method will show a View named About One more item to point out is how the Index action assigns a string to a collection called ViewData The ViewData collection is one way for a Controller to pass Model data to a View I ll cover more on Controllers, including how to create your own, in a later part of this chapter, but now, let s do a quick review of Views so that you can see what happens when they are invoked by the Controller

A View is what displays in the browser and allows interaction with the user The View can display any information that a Controller passes to it For example, notice that the Index action in Listing 9-1 assigns a string Welcome to ASPNET MVC! with the Message key in the ViewData collection

Figure 9-3 shows the View in the browser, displaying the message Listing 9-2 shows the Hypertext Markup Language (HTML) of the View displaying the message The View actually has a combination of HTML and ASPNET markup, sometimes referred to as ASPX, but I ll refer to it as just HTML for the rest of the chapter

Listing 9-2

<%@ Page Language="C#" MasterPageFile="~/Views/Shared/SiteMaster" Inherits="SystemWebMvcViewPage" %> <asp:Content ID="indexTitle" ContentPlaceHolderID="TitleContent" runat="server"> Home Page </asp:Content> <asp:Content ID="indexContent" ContentPlaceHolderID="MainContent" runat="server"> <h2><%= HtmlEncode(ViewData["Message"]) %></h2> <p> To learn more about ASPNET MVC visit <a href="http://aspnet/mvc" title="ASPNET MVC Website"> http://aspnet/mvc </a> </p> </asp:Content>

A quick overview of Listing 9-2 shows that there is a Page directive with a couple of Content containers The Page directive specifies a MasterPage and Inherits attributes A MasterPage is a separate file that holds common HTML that can be shown on all pages of a site You ll see how the MasterPage works soon, but let s stay focused on the current file in Listing 9-2 until then ASPNET MVC will compile this HTML into code behind the scenes, and the generated code will derive from the class defined by the Inherits attribute The first Content container can hold metadata that goes into an HTML header The second Content container has the information that will display on the screen Notice the HtmlEncode(ViewData["Message"]) inside of binding tags <%= and %> Any time you add code or need to access ViewData that was passed by the Controller, you will use the binding tags Encode is one of several helper methods of the Html class, more of which you ll see soon The purpose of Encode is to translate HTML tags into their encoded representations for security purposes, ensuring that you don t show any harmful JavaScript, or other markup that could possibly execute, to the user ViewData["Message"] should be familiar, as it was set in the Index action in Listing 9-2 but is now being read and displayed on the screen by this View