Ultimate ASP NET Core Web API Tutorial for Beginners Step by Step Guide

Embarking on your ASP.NET Core Web API journey? You're in the right place! This tutorial is designed to help you understand and create your first ASP.NET Core Web API from scratch. Let's dive in!

ASP.NET Core Web API is a framework for building web APIs that supports both classic ASP.NET platforms and cross-platform development on Windows, Linux, and macOS. It allows you to reach a broad range of clients, including browsers and mobile devices.

Setting up the Development Environment

Before we start building our API, we need to ensure we have the right tools installed. For this, we'll use the .NET Core SDK, Visual Studio (optional), and a terminal or command prompt.

First, download and install the .NET Core SDK from the official Microsoft website. If you prefer an Integrated Development Environment (IDE), you can use Visual Studio, ensuring you select the 'ASP.NET Core development' workload during installation.

Creating a New ASP.NET Core Web API Project

Let's now create a new ASP.NET Core Web API project using the terminal or command prompt.

Open your terminal or command prompt, navigate to your projects directory, and run the following command:

.NET new webapi -n MyWebApiProject --framework net5.0

This command will create a new ASP.NET Core Web API project named 'MyWebApiProject' using the .NET 5.0 framework.

Running the Web API Project

Now, let's run our newly created project. Navigate into your project directory:

cd MyWebApiProject

Then, run the following command to start the development server:

dotnet run

Your web API should now be running on . You can access the Swagger UI at to interact with your API.

Creating Your First Controller

Now that our project is set up let's create our first API controller.

In your project directory, navigate to the 'Controllers' folder and create a new file named 'WeatherForecastController.cs'.

Defining the API Controller

Inside this new file, let's define our API controller. Here's a basic example:

```csharp using Microsoft.AspNetCore.Mvc; using System.Collections.Generic; namespace MyWebApiProject.Controllers { [ApiController] [Route("[controller]")] public class WeatherForecastController : ControllerBase { private static readonly string[] Summaries = new[] { "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Swinging", "Torrential" }; [HttpGet] public IEnumerable Get() { var forecast = Enumerable.Range(1, 5).Select(index => new WeatherForecast { Date = DateTime.Now.AddDays(index), TemperatureC = Random.Shared.Next(-20, 55), Summary = Summaries[Random.Shared.Next(Summaries.Length)] }).ToArray(); return forecast; } } } ```

Here, we've created a simple controller with a single API endpoint ('/WeatherForecast') that returns a list of random weather forecasts.

Testing the Web API

Let's test our new API using SwaggerUI (). Refresh the page, and you'll see our new endpoint listed. Click 'Try it out!' to send a GET request and verify the response.

Congratulations! You've just created and tested your first ASP.NET Core Web API. This is just the beginning - there's much more to explore, like other HTTP methods, middleware, data models, and database integration. Stay tuned for more tutorials!