Creating Your First ASP.NET Core Application Step by step Implementation and Top 10 Questions and Answers

Last Update: April 01, 2025 16 mins read Difficulty-Level: beginner

Creating Your First ASP.NET Core Application

Introduction ASP.NET Core is a high-performance, open-source, and cross-platform framework for building modern web applications and services. With its modular architecture, extensive library support, and continuous updates, it has become a popular choice among developers. In this guide, we will take you through the process of creating your first ASP.NET Core application from scratch, covering everything you need to know to get started.

Prerequisites Before diving into the project, ensure you have the following installed:

.NET SDK: Install the latest version from the .NET downloads page.
Visual Studio or Visual Studio Code: Although you can use any code editor, Visual Studio provides a rich set of tools for ASP.NET development. You can download Visual Studio Community edition for free here.

Step 1: Setting Up Your Project

Open a Command Prompt or Terminal.
Create a new directory for your project and navigate into it:
```
mkdir MyFirstAspNetCoreApp
cd MyFirstAspNetCoreApp
```
Create a new ASP.NET Core web application by running:
```
dotnet new webapp -n MyFirstAspNetCoreApp -o .
```
The -n flag specifies the project name, and -o . tells the command to create the project in the current directory.
Restore the project dependencies by running:
```
dotnet restore
```

Step 2: Explore the Project Structure The command you ran generated a basic ASP.NET Core Web Application. Let’s go through the key files and directories:

Program.cs: The entry point of the application. In ASP.NET Core 6.0 and above, the Program.cs file is greatly simplified. It sets up the web host and configures the request pipeline.
Startup.cs: This file is where you configure and specify the services your application will use and how HTTP requests are handled. In ASP.NET Core 6.0 and later, some of the configurations from Startup.cs are now handled within the Program.cs file.
wwwroot: Contains static files like HTML, CSS, JavaScript, and images.
Controllers: Contains the classes responsible for handling HTTP requests.
Views: Contains the razor view templates for displaying content.
appsettings.json: Used for application-wide configurations such as connection strings and logging settings.
MyFirstAspNetCoreApp.csproj: The project file that contains the project properties and dependencies.

Step 3: Build and Run the Application

Build the application to ensure everything is set up correctly:
```
dotnet build
```
Run the application by executing:
```
dotnet run
```
By default, it will run the application on https://localhost:5001 or http://localhost:5000 if you have HTTPS turned off.
Open your browser and navigate to https://localhost:5001 (or the URL specified in the terminal). You should see the welcome page of your ASP.NET Core application.

Step 4: Modify the Application Let’s make some simple changes to understand how the application works.

Open the Pages/Privacy.cshtml file located in the Pages directory.

Modify the content of the page to include your name or a unique message:

@page
@model PrivacyModel
@{
    ViewData["Title"] = "Privacy Policy";
}

<h1>@ViewData["Title"]</h1>

<p>Your custom privacy policy here, e.g., Hello, [Your Name]!</p>

Save the changes and return to your browser. Navigate back to the privacy page (/Privacy) to see your changes reflected.

Step 5: Understanding the Razor Pages ASP.NET Core uses Razor Pages to handle the web pages. Razor Pages combines the benefits of MVC (Model-View-Controller) and Web Forms into a less verbose model.

Pages/Privacy.cshtml: The razor view file that defines the UI.
Pages/Privacy.cshtml.cs: The code-behind file for the razor page that contains the logic associated with the view.

Step 6: Add a New Page Let's create a new page that displays a greeting message based on a URL parameter.

Create a new file named Greeting.cshtml in the Pages directory.

Add the following contents to the file:

@page "{name}"
@model GreetingModel
@{
    ViewData["Title"] = "Greeting";
}

<h1>@ViewData["Title"]</h1>

<p>Hello, @Model.Name!</p>

Create a new file named Greeting.cshtml.cs in the same directory:

using Microsoft.AspNetCore.Mvc.RazorPages;

public class GreetingModel : PageModel
{
    public string Name { get; set; } = "Guest"; // Default name

    public void OnGet(string name)
    {
        Name = name ?? Name;
    }
}

Test the new page: Run the application if it's not already running. Navigate to https://localhost:5001/Greeting/YourName, replacing YourName with any name you'd like. The page will display a greeting message for that name.

Step 7: Deploy Your Application Once your application is ready, you can deploy it to various hosting services like Azure, IIS, or any other platform that supports ASP.NET Core.

Publish the application using the following command:
```
dotnet publish -c Release -o ./publish
```
This command compiles and publishes the application in Release mode to the publish directory.
Upload the published files to your chosen host.
Configure your host to point to the publish directory.

Conclusion In this guide, we created a basic ASP.NET Core application, explored its structure, and made modifications to understand how it works. ASP.NET Core offers an extensive ecosystem, including various templating engines, middleware support, and robust library integration, making it a powerful framework for building modern web applications. By following these steps, you're now well on your way to becoming proficient in ASP.NET Core development. Happy coding!

Creating Your First ASP.NET Core Application: Step by Step Guide

Introduction

Getting started with ASP.NET Core can be an exciting yet daunting experience, especially if you’re new to web development. This guide aims to simplify the process by providing a step-by-step example. We'll create a basic ASP.NET Core web application, set up routing, run the application, and understand how data flows through the application. By the end of this tutorial, you'll have a solid foundation to build more complex applications.

Prerequisites

Before you begin, ensure you have the following installed on your machine:

.NET SDK: Download and install the latest version from the .NET website.
Code Editor: Visual Studio or Visual Studio Code are recommended.
Node.js and npm (optional, for future projects using JavaScript frameworks).

Step 1: Create a New ASP.NET Core Project

Open a Terminal or Command Prompt:
- Navigate to the directory where you want to create your project.
Create a New MVC Project:
- Run the following command:
```
dotnet new mvc -n MyFirstAspNetCoreApp
```
- This command creates a new MVC (Model-View-Controller) project named MyFirstAspNetCoreApp.
Navigate into the Project Directory:
- Change into the newly created project directory:
```
cd MyFirstAspNetCoreApp
```

Step 2: Understand the Project Structure

When you create a new MVC project, the following directories and files are generated:

Controllers: Contains controller classes responsible for handling incoming HTTP requests.
Models: Contains model classes representing data.
Views: Contains Razor views, which are used to render HTML responses.
wwwroot: Contains static files such as CSS, JavaScript, and images.
Program.cs: The entry point of the application.
Startup.cs: (In older versions) Configures services and the request pipeline.

For newer versions, Startup.cs is merged into Program.cs.

Step 3: Set Up Routing

Routing in ASP.NET Core maps URL patterns to controller actions. By default, a new MVC project uses attribute routing.

Open Controllers/HomeController.cs:
- This file contains the default HomeController class.

Modify the HomeController:

Add a new action method for demonstration purposes. Open HomeController.cs and add the following code:

using Microsoft.AspNetCore.Mvc;

public class HomeController : Controller
{
    public IActionResult Index()
    {
        return View();
    }

    public IActionResult About()
    {
        ViewData["Message"] = "Your application description page.";
        return View();
    }

    public IActionResult Contact()
    {
        ViewData["Message"] = "Your contact page.";

        return View();
    }

    public IActionResult Privacy()
    {
        return View();
    }

    [ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
    public IActionResult Error()
    {
        return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
    }

    // New Action Method
    public IActionResult Greet(string name)
    {
        ViewData["Message"] = $"Hello, {name}!";
        return View();
    }
}

Create a View for the New Action:
- Create a new file named Greet.cshtml in the Views/Home directory with the following content:
```
@{
    ViewData["Title"] = "Greetings";
}

<h2>@ViewData["Message"]</h2>
```
Set Up Routing:
- The Greet action method is already set up for attribute routing. The URL pattern for this action is /Home/Greet?name=[yourname].

Step 4: Run the Application

Build and Run the Application:
- In the terminal, execute the following command:
```
dotnet run
```
- Open a web browser and navigate to https://localhost:5001 (the port may vary).
Test the New Route:
- Navigate to https://localhost:5001/Home/Greet?name=John to see the greeting message: "Hello, John!".
- You can change the name query parameter to see different greetings.

Step 5: Understand the Data Flow

Understanding data flow in an MVC application is crucial for developers.

Request Processing:
- A client (e.g., browser) sends an HTTP request to the server.
- ASP.NET Core middleware processes the request and routes it to the appropriate controller and action method.
Controller Actions:
- Controller actions handle the request, process data, and return a response.
- In the Greet action, the name parameter is captured from the query string, and a greeting message is created.
Views:
- The controller passes data to the view using ViewData or ViewBag.
- The view generates HTML based on the data and sends it back to the client.
Data Models:
- For more complex data handling, use models to represent data.
- In this example, ViewData is used for simplicity.

Conclusion

Congratulations! You've created your first ASP.NET Core application, set up routing, and understood the data flow. This foundational knowledge will enable you to build more advanced applications in the future. Experiment with different routing configurations, models, and views to deepen your understanding of ASP.NET Core. Happy coding!

Top 10 Questions and Answers for Creating Your First ASP.NET Core Application

1. What is ASP.NET Core?

Answer: ASP.NET Core is a high-performance, open-source, cross-platform framework for building modern, cloud-based, internet-connected applications. It is a successor to traditional ASP.NET and offers a more modular design, enhanced performance, and support for multiple platforms including Windows, MacOS, and Linux.

2. What are the prerequisites to create an ASP.NET Core application?

Answer: To get started with ASP.NET Core development, you should have:

.NET SDK: Essential for compiling and running .NET applications.
Code Editor: Visual Studio, Visual Studio Code, or any other editor of your choice.
Basic Knowledge of C#: ASP.NET Core is built on C#, so familiarity with this programming language is beneficial.
NuGet Package Manager: For managing external dependencies.

3. How do I create a new ASP.NET Core project?

Answer: You can create a new ASP.NET Core project using Visual Studio or the .NET CLI. Here’s how you can do it via the CLI:

# To create a new project
dotnet new mvc -n MyFirstAspNetApp

# Navigate into the project directory
cd MyFirstAspNetApp

# To run the project
dotnet run

This command creates a new ASP.NET Core MVC application named "MyFirstAspNetApp" and runs it. You can view it by navigating to http://localhost:5000 in your web browser.

4. What is Program.cs in an ASP.NET Core application?

Answer: In ASP.NET Core, Program.cs serves as the entry point of the application. It configures and launches the web host, setting up middleware pipeline, services, and other essential components. Here’s a snippet of what it might look like:

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddControllersWithViews();

var app = builder.Build();

if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Home/Error");
    app.UseHsts();
}

app.UseHttpsRedirection();
app.UseStaticFiles();

app.UseRouting();

app.UseAuthorization();

app.MapControllerRoute(
    name: "default",
    pattern: "{controller=Home}/{action=Index}/{id?}");

app.Run();

5. Can you explain the MVC pattern in ASP.NET Core?

Answer: Yes, ASP.NET Core supports the Model-View-Controller (MVC) architectural pattern, which helps in organizing your code into separate components based on their function:

Model: Represents data and business logic.
View: Displays data to the user in a specified format.
Controller: Handles user input and updates the model accordingly.

In an ASP.NET Core MVC application, these components interact with each other as follows:

The controller handles the incoming request from the user.
It then interacts with the model to retrieve or update data.
Finally, it passes the data to a view, which formats it for the user.

6. How do I add a new controller in an ASP.NET Core MVC application?

Answer: To add a new controller, you can use Visual Studio, or manually create a new file with the appropriate class. Here’s how you can add a controller manually:

Create a new .cs file in the Controllers folder of your project.
Add the following code to define a new controller:

using Microsoft.AspNetCore.Mvc;

namespace MyFirstAspNetApp.Controllers
{
    public class HelloController : Controller
    {
        public IActionResult Index()
        {
            return View();
        }
    }
}

Create a corresponding view in the Views/Hello folder with an Index.cshtml file:

<h1>Hello, World!</h1>

7. How to configure routing in ASP.NET Core?

Answer: Routing in ASP.NET Core is used to map URLs to specific endpoints (action methods on controllers). The default routing configuration is defined in Program.cs:

app.MapControllerRoute(
    name: "default",
    pattern: "{controller=Home}/{action=Index}/{id?}");

This route pattern maps URLs to specific controllers and actions. For example, a URL like http://example.com/Home/About will map to the About action method in the HomeController.

You can also define custom routes if needed:

app.MapControllerRoute(
    name: "custom",
    pattern: "product/{id}",
    defaults: new { controller = "Product", action = "Details" });

8. How do you handle errors and exceptions in ASP.NET Core?

Answer: ASP.NET Core provides several mechanisms to handle errors and exceptions:

Development Mode vs. Production Mode: Use different error-handling strategies for development and production environments. In development mode, detailed error pages are shown to help with debugging, whereas in production mode, a generic error page is displayed.
Middleware for Error Handling: Use middleware components like UseExceptionHandler and UseHsts for better error handling.
Custom Error Pages: Configure custom error pages for specific HTTP status codes, such as 404 (Not Found) or 500 (Internal Server Error).
Model Validation: Use data annotations and other validation mechanisms to validate user input.
Global Exception Handling: Implement a global exception filter to catch and log unhandled exceptions:

services.AddControllersWithViews(options =>
{
    options.Filters.Add(new ExceptionFilterAttribute());
});

9. How to add static files in ASP.NET Core?

Answer: Static files such as HTML, CSS, JavaScript, and image files can be served by an ASP.NET Core application. To enable static file support, use the UseStaticFiles middleware in Program.cs:

app.UseStaticFiles(); // Enables static files middleware

Static files are served from the wwwroot directory by default. Place your static files in this directory and they will be accessible directly through the browser.

10. How to publish an ASP.NET Core application?

Answer: Publishing an ASP.NET Core application prepares it for deployment. You can publish your application using Visual Studio or the .NET CLI. Here’s how you can publish it using CLI:

dotnet publish -c Release -o publishedapp

This command compiles your application, runs optimizations like Razor file compilation, and places the output files in the publishedapp folder.

For deploying the application, you can use various hosting providers including Azure App Service, AWS, and IIS on Windows. Each hosting provider has specific steps to deploy published applications, involving configuration and deployment settings.

By following these steps and utilizing the resources of the .NET ecosystem, you can create, manage, and deploy robust ASP.NET Core applications efficiently.