In this sample chapter from ASP.NET Core Application Development: Building an application in four sprints, the author team recaps the basics of models, views, controllers, middleware, and dependency injection.
The M, the V, and the C of it
Let’s face it, the MVC Framework is a pretty boring name. The acronym used in the title is from the well-known Model-View-Controller pattern, and it helps to organize a project. If you’re familiar with it, the name literally spells out some of the original intent to separate concerns, and moves away from the other common pattern at the time known as Page-Controller. The name can also be misleading. The framework is much more than just models, views and controllers. ASP.NET Core MVC has a growing set of tooling and libraries available to that help developers create great applications, worthy of the modern web world.
Let’s do a quick recap on the aspects you should already understand, and then move into some more interesting aspects of the framework, officially known as ASP.NET Core MVC.
Diving into Models
First up is the letter M, so we’ll start with Models. The model represents the data that we need to properly render an experience, or part of an experience, for a customer. Customers are navigating to a page in the application that is data-driven, and models are the data part. However, as far as intent goes, the model in question is actually what you’ll be using to support the rendering of the view, and not the entity or entities in question in which you persist to the database.
Let’s consider this example from Alpine Ski House’s possible database design that deals with user account summaries, as shown in Figure 3-1. When you want to indicate to the user that she has a current season pass, you don’t want to return the list of season passes to the view and iterate over the collection to see if one exists that has not yet expired.
FIGURE 3-1 A screen shot showing a sampling of tables that might be used to model purchasing season passes
Returning all of this information to the view would be more than is required. Listing 3-1 contains a view model that might more closely approximate the information you would want to display to the user. As you can see, this is a POCO that sports the properties you can use to satisfy the view requirements without the view needing to make any decisions about what to display or any implementation of business logic. The view doesn’t need to know what qualifies as a current season pass nor does it need to sift through any of the purchase details or iterate through child records in related tables to make sense of the data.