Build RESTful APIs Using ASP.NET Core API

ASP.NET Core is a web framework for building web applications and RESTful APIs. In this tutorial, we will cover how to build RESTful APIs using ASP.NET Core API.

Setting up the Environment

Before we get started, we need to set up our development environment. Here are the steps you need to follow:

1. Download and install .NET Core SDK
2. Install an editor like Visual Studio Code

Creating a New ASP.NET Core API Project

To create a new ASP.NET Core API project, follow these steps:

1. Open your terminal and navigate to the directory where you want to create your project.
2. Run the following command to create a new API project:

dotnet new webapi -n MyAPI

This command will create a new API project named MyAPI.

Syntax

The syntax for creating an API endpoint using ASP.NET Core API is as follows:

[Route("api/[controller]")]
[ApiController]
public class MyController : ControllerBase
{
    [HttpGet]
    public ActionResult<IEnumerable<string>> Get()
    {
        return new string[] { "value1", "value2" };
    }
}

In the above code, we have created an API endpoint that returns an array of strings. The [Route] attribute is used to define the URL path for our API endpoint.

Example

Let's add a new API endpoint that returns a list of customers. Here's how we can do that:

[Route("api/[controller]")]
[ApiController]
public class CustomersController : ControllerBase
{
    private readonly List<Customer> _customers = new List<Customer>(){
        new Customer(){
            Id = 1,
            FirstName = "John",
            LastName = "Doe"
        },
        new Customer(){
            Id = 2,
            FirstName = "Jane",
            LastName = "Doe"
        }
    };

    [HttpGet]
    public ActionResult<IEnumerable<Customer>> Get()
    {
        return _customers;
    }
}

In the above code, we have created an API endpoint that returns a list of customers. We have added a list of customers manually for demonstration purposes.

Output

To run the API project, use the following command:

dotnet run

This command will start the API server. You can test the API by sending a GET request to the URL http://localhost:5000/api/customers. You should receive the list of customers we declared earlier.

Explanation

ASP.NET Core API makes it easy to create RESTful APIs. You can define API endpoints using the [Route] attribute, and you can return data using the ActionResult class.

In the example above, we have created an API endpoint that returns a list of customers. We have used the [HttpGet] attribute to denote that this is a GET endpoint.

Use

RESTful APIs are commonly used for communication between web applications and mobile applications. With ASP.NET Core API, you can easily create a RESTful API that can be consumed by any client using HTTP requests.

Important Points

• ASP.NET Core is a web framework for building web applications and RESTful APIs.
• The [Route] attribute is used to define the URL path for an API endpoint.
• The ActionResult class is used to return data from an API endpoint.

Summary

In this tutorial, we covered how to build RESTful APIs using ASP.NET Core API. We started by setting up our development environment and creating a new API project. Then, we learned about the syntax and examples of creating an API endpoint using ASP.NET Core API. Finally, we tested our API by sending a GET request and received the response in JSON format.