C# 4 and .NET 4

1262 ❘ ChaPTer 42 Asp.net dynAmic dAtA And mvc
At this point, you can run the application and see what’s there. There’s a perfectly functional home page
with an About page and a registration/log on system. However, it’s easier to learn about how everything
works if you work through modifying what is there.
adding a Model
The order in which you add model, view, and controller code will vary according to what you want to
achieve. Typically, though, you will start with a model, particularly if you want to access data in a database.
By starting with a model, you then have access to strongly typed model classes from the outset, and the ASP
.NET MVC wizards will be able to use the model type information to automatically generate a lot of the
scaffolding code you require.
In this example, you will use the MagicShop.mdf database introduced earlier in the chapter. Because the
sample code is a web application rather than a web site, you cannot simply copy this file to the App_Data
directory. Instead, you must add it to the App_Data directory by right-clicking on the directory and selecting
the Add ➪ Existing Item . . . menu item, then browsing to the database file and clicking Add. Or, if you prefer,
you can build a database in place through Visual Studio, connect to a different database, or select an entirely
different data source.
Once you have a data source in place, you can add a model using whatever technique you prefer. This
includes using LINQ to SQL classes, an ADO.NET Entity Data Model, or custom classes that you design
from scratch. Whichever method you use, you should place the code in the Models folder of the application.
For simplicity, add an ADO.NET Entity Data Model with the name MagicShop by right-clicking on the
Models directory and selecting the Add ➪ New Item . . . menu item. This template is located in the Data
templates section. Since a data source exists, most of the default settings in the wizard will already be
configured for you, so all you have to do is to select the tables to model (all of them).
After adding your model code, you must build the solution before proceeding in order to make the
subsequent wizards aware of your new code.
adding a Controller
To add a controller for your new model, you use the ASP
.NET MVC Add Controller Wizard. You access this
wizard by right-clicking on the Controllers folder and
selecting the Add New Controller menu item.
Add a controller for the products in the MagicShop database
with the name ProductsController, as shown in Figure 42-9,
ensuring that the check box is checked as shown.
figure 42-9
The controller that is added contains several methods, each of which returns an ActionResult.
These methods encapsulate operations that users (or other code) can perform, and each is exposed
through a URL through routing (see the section “URL Operation Routing” for more details). The
methods added by the wizard are shown in the following table.
meThod
Index()
Create()
Details()
Edit()
desCriPTion
This is the default operation for the controller, which views will use if no other method is
specified; for example, when a view is first displayed. For the products controller, you want
this to display a list of products.
There are two methods added for creating new items. The first, which takes no parameters,
is used when a request to add a new item is triggered, perhaps with an “Add new item”
link. The second is responsible for actually adding an item.
This method is responsible for displaying a detail view of a single item.
The two edit methods are similar to the two create methods. The first takes a single ID
value and will trigger editing for a specific, existing item. The second takes an ID and a
second parameter that specifies the values to change.
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