Introduction

In the previous chapters, we have gone more in depth with both the C (Controller) and the V (View) of the MVC pattern, so in this chapter, we'll focus on the M (Model). We're talking about it last because you can actually have a website based on the MVC pattern without using a Model, although that would be a pretty simple website.

What is a Model?

As we discussed in the quick start part of this tutorial, where we quickly added a Controller, a View and a Model to our project, the Model in an MVC application should represent the current state of the application, as well as business logic and/or operations. A Model can be any kind of object found in the framework. It could in fact be a simple number or string, or it could be a complex object instantiated from a class, e.g. a User class which holds information about a user, a GuestbookEntry item which contains a post to a guestbook or anything else. That also means that your Model can be a class you already have, e.g. something that comes from the database, or a class that you create specifically to become a Model for one or several Views.

Một đặc tính quan trọng của MVC là chia nhỏ vấn đề băng cách che dấu thông tin bên trong. Trong MVC, cả View và Controller đều có thể dựa trên Model nhưng Model không phụ thuộc vào View hay Controller. Model có thể tồn tại ngoài MVC framework, ví dụ dùng cho ứng dụng desktop nên có thể kiểm thử Model thông qua unit test.

As mentioned, the Model can be a class already defined in your project, or it can be a new class you add specifically to act as a Model. Therefore, Models in the ASP.NET MVC framework usually exists in a folder called "Models", or they come from outside of the project, e.g. from a class library. A Model doesn't have to inherit from a specific base class or anything like that - they are truly just regular .NET classes. There are a couple of ways to enrich your Model classes with MVC-related information though, but we'll discuss that later.

Summary

Model trong MVC có thể là trạng thái của ứng dụng cũng như nghiệp vụ. Trong các bài tiếp theo chúng ta sẽ tìm hiểu về Model theo hướng chủ đề.