ASP.NET CORE MVC THE CONTROLLER

If a user finds a course he or she likes, as described in step five, he or she will enter a course detail page with the option to register to purchase the course.

ASP.NET Core provides us with two equally good technologies for implementing the project’s UI. Both are based on the same technology stack, the only difference being in how files are stored within the project.

Let’s start by looking at the first ASP.NET Core MVC. The Model contains the Business logic and accesses the database. Once we have extracted the data from the database, we will pass it to the View, which is responsible for presenting the data in HTML format by taking advantage of the Razor engine. Finally, there is the controller that handles the user request, passes the data first to the Model then to the View.

Let us look at the MVC pattern in more detail. Suppose a user wants to view the details of the course with ID=5, extracts the information from the request and passes it to the Model. The Model with the data provided by the Controller extracts the data from a database and still in raw format puts it into an object that it passes back to the Controller. The Controller turns the request over to the View to create well-formatted, user-pleasing HTML output, which it then passes back to the Controller and the latter can send the response to the client.

Only the controller is the essential element, in some niche situations the View may not be necessary

Summary slide.

CREATE A CONTROLLER AND ITS ACTIONS

The class of a Controller must stand by conventions. The first part is arbitrary, the second Controller must take on that name. It derives from the Controller class that gives us facilities. Inside are the methods, the type returned, and the method name, which can be arbitrary. Returns a View object defined in the Controller base class. The object passed to the View serves the View to produce HTML markup.

Normally the Index action is the one that returns the list of courses, while Detail.

I’ll show you with an image how the directories should be organized.

Note that in the Views there must be a folder having the same name as the first part of the Controller Courses and its action Detail in the example, always having the same name as the Action of the controller. This is by convention. The .cshtml extension denotes a View containing HTML but also C# code. Let’s see how the Razor Pages are organized.

We create our first Controller.

ADD ROUTING MIDDLEWARE

The Routing Middleware goes to see if there is a Controller called Courses, having an action Detail and finding match it can handle the request. calls the Controller with its Action, and the Controller will return the command to the Middleware producing a response.

Let’s see once the Routing Middleware is configured what the page looks like. Find the detailed explanation in the downloadable code from GITHUB.

Let’s see how it all works graphically. The following request arrives. /courses/detail/5. Routing Middleware asks: Does the route of the request conform to the set template? The answer is affirmative since the request contains the three fragments. ASP.NET Core MVC services added with the AddMvc() line go looking for a controller called CoursesController, and pass the ball to its Action Detail by providing The id 5. This is sufficient to produce the http response.