Introduction to ASP.NET Core
ASP.NET Core is an open-source web framework that can be used to develop web applications and services that can be run on Windows, macOS, and Linux. It was created by Microsoft as a successor to earlier versions of ASP.NET. ASP.NET Core is built on top of .NET Core, which is a free, open-source, and cross-platform framework for building modern applications.
ASP.NET Core Tutorial
In this tutorial, we will go through the basics of ASP.NET Core and how to build a simple web application using the MVC (Model-View-Controller) pattern. The tutorial assumes that you have some knowledge of C# programming language and HTML/CSS.
Step 1: Creating a new project
To create a new ASP.NET Core project in Visual Studio, follow these steps:
1. Click on File -> New -> Project.
2. Select .NET Core from the list of project types on the left-hand side of the window.
3. Select ASP.NET Core Web Application from the list of templates.
4. Choose a name for your project and select a location where it will be saved.
5. Click on the Create button.
In the next window, you can select the type of project template you want to use. For this tutorial, we will use the MVC template, which will give us a ready-made application with the basic structure and files we need to build our web application.
Step 2: Understanding the basic structure of an ASP.NET Core project
In an ASP.NET Core project, the main files and folders are as follows:
1. Program.cs – This file contains the entry point for the application. It sets up the web server and starts listening for HTTP requests.
2. Startup.cs – This file is where you configure the application’s services and middleware. Services are objects that provide functionality to the application, like database access or authentication. Middleware are objects that handle requests and responses, like logging or routing requests to the correct controller.
3. wwwroot folder – This folder contains static files that will be served directly by the web server, like images, CSS, and JavaScript files.
4. Controllers folder – This folder contains the controllers for the application. Controllers are the glue between the models and views in the MVC pattern. They handle HTTP requests, perform business logic, and return responses to the client.
5. Views folder – This folder contains the views for the application. Views are the user interface components that are rendered in response to HTTP requests.
6. Models folder – This folder contains the models for the application. Models represent the data and business logic of the application.
Step 3: Adding a controller and a view
Let’s create a simple controller and a view to display a welcome message. To do this, follow these steps:
1. Right-click on the Controllers folder and select Add -> Controller.
2. Choose Empty Controller from the list of templates and give it a name, like HomeController.
3. Open the HomeController.cs file and add the following code:
public class HomeController : Controller
{
public IActionResult Index()
{
return View();
}
}
4. Right-click on the Views folder and select Add -> View.
5. Give it a name, like Index.cshtml, and click on the Add button.
6. Open the Index.cshtml file and add the following code:
Welcome to ASP.NET Core!
7. Run the application by clicking on the green Play button in Visual Studio.
When you run the application, you should see the welcome message displayed in your web browser. This is just a simple example, but it demonstrates how controllers and views work together to provide a web application with a user interface and business logic.
Step 4: Adding a model and a database
Let’s add a model to our application to represent some data, and use Entity Framework Core to access a database. To do this, follow these steps:
1. Right-click on the Models folder and select Add -> Class.
2. Give it a name, like Message, and add the following code:
public class Message
{
public int Id { get; set; }
public string Text { get; set; }
}
3. Open the Startup.cs file and add the following code to the ConfigureServices method:
services.AddDbContext
options.UseSqlServer(Configuration.GetConnectionString(“DefaultConnection”)));
services.AddControllersWithViews();
4. Open the appsettings.json file and add the following code:
{
“ConnectionStrings”: {
“DefaultConnection”: “Server=(localdb)\\mssqllocaldb;Database=MyDatabase;Trusted_Connection=True;MultipleActiveResultSets=true”
}
}
5. Run the following command in the Package Manager Console to create a migration:
Add-Migration InitialCreate
6. Run the following command to apply the migration to the database:
Update-Database
7. Open the HomeController.cs file and modify the Index method to use the database:
private readonly AppDbContext _db;
public HomeController(AppDbContext db)
{
_db = db;
}
public IActionResult Index()
{
var message = new Message { Text = “Hello from ASP.NET Core!” };
_db.Messages.Add(message);
_db.SaveChanges();
var messages = _db.Messages.ToList();
return View(messages);
}
8. Modify the Index.cshtml file to display the messages from the database:
@foreach (var message in Model)
{
@message.Text
}
9. Run the application and you should see the message “Hello from ASP.NET Core!” displayed on the screen.
FAQs
1. What is ASP.NET Core?
ASP.NET Core is an open-source web framework that can be used to develop web applications and services that can be run on Windows, macOS, and Linux.
2. What is the MVC pattern in ASP.NET Core?
The MVC pattern stands for Model-View-Controller. It is a design pattern for organizing the code of a web application into three parts: the model (business logic and data access), the view (user interface), and the controller (handles HTTP requests and responses).
3. What is Entity Framework Core?
Entity Framework Core is an object-relational mapping (ORM) framework that can be used to access databases in an ASP.NET Core application. It provides an abstraction layer between the application code and the database, making it easier to work with data.
4. What are services and middleware in ASP.NET Core?
Services are objects that provide functionality to the application, like database access or authentication. Middleware are objects that handle requests and responses, like logging or routing requests to the correct controller. They are configured in the Startup.cs file.
5. How can I run an ASP.NET Core application on Linux?
ASP.NET Core can be run on Linux using the .NET Core runtime. You will need to install the runtime on your Linux machine and then run your ASP.NET Core application using the dotnet command line tool.