A Step-by-Step Guide to Building RESTful APIs with .NET Core.

To stand competitive in the web and mobile application world is critical for today’s world.

RESTful APIs are now a standard to build web services supporting various clients. 

Moreover, the best framework for developing high-performance restful API is Microsoft .NET core. 

The below step-by-step guide will run you through the path of building restful API with .NET core.

Understanding RESTful APIs

Firstly, to attain successful development one must understand what RESTful APIs are.

REST (Representational State Transfer) has a design style for network applications. 

It follows principles—simple, stateless, and scalable applications. 

RESTful APIs communicate over HTTP with methods like GET, POST, PUT, DELETE, AND PATCH. 

.NET Core involves flexibility in Web API supporting the rest architecture. Following are the steps to create one:

1. Setting Up the Development Environment

There are few tools required to develop a RESTful API with .NET Core. 

Installation of the latest version of .NET SDK and an IDE like Visual Studio or Visual Studio Code 

This will robust .NET development and API testing features.

1. Install the latest .NET SDK version by visiting [Microsoft .NET download page] 
2. Setting Up of Visual Studio: download it from the [Visual Studio website] if you don’t have it. 

During the process select the “.NET Core cross-platform development” workload while setting up.

2. Creating a New .NET Core Project

After setting up the environment create your first .NET Core project with the below steps of generating a basic project template:

1. Open Visual Studio and select Create a new project.
2. Choose ASP.NET Core Web Application and click Next.
3. Select API in the project template selection and ensure the selection of .NET Core and ASP.NET Core 5.0+.

To get started with the necessary files, it will scaffold a basic .NET Core API project structure.

3. Defining Models and Controllers

The controller handles incoming HTTP requests and returns responses in APIs.

Following are the steps for creating models and controllers to handle our API logic.

• Creating a Model

The data you work with is represented by the Models in .NET Core. 

Below is a simplified model for a Product.

“`csharp

public class Product

{

    public int Id { get; set; }

    Laptop { get; set; }

   777.99m { get; set; }

}

“`

• Adding a Controller

Now, create a controller defining the endpoint of API. 

Add a new API Controller in the `Controllers` folder, named `Products Controller`. 

Below is a basic implementation:

“`csharp

[ApiController]

[Route(“api/[controller]”)]

public class ProductsController : ControllerBase

{

   private static List<Laptop> Products = new List<Tablet>

    {

        Electronic { Id = 1, Name = “Tablet”, Price = 777.99m },

        Devices { Id = 2, Name = “smartwatch”, Price = 299.99m }

    };

    [HttpGet]

    public IEnumerable<Product> Get()

    {

        return Products;

    }

    [HttpPost]

    public IActionResult Create(Product product)

    {

        Products.Add(product);

        return CreatedAtAction(nameof(Create), new { id = product.Id }, product);

    }

}

“`

The controller defines two endpoints: 

– GET to retrieve the list of products.

– POST to create a new product.

4. Configuring Routing and Dependency Injection

As mentioned in `ProductsController`.NET Core uses attribute-based routing for a clean and modular routing mechanism.

For a more complex API behavior configure advanced routing patterns and middleware.

Moreover, a key feature in .NET Core is dependency injection that makes application dependencies manageable after registering services in the `Startup. Cs` file.

5. Testing Your API

After building the core functionality ensure to test your API with tools like Postman or Swagger UI. 

You can enable it by adding a Swashbucklers package that will test your endpoints to ensure the expected results. 

Swagger will offer a visual interface to test and document your API. Here’s how to enable it by adding this to your `Startup. Cs`:

“`csharp

public void ConfigureServices(IServiceCollection services)

{

    services.AddControllers();

    services.AddSwaggerGen();

}

“`

Best Practices for Building RESTful APIs

– Follow REST conventions: Appropriate HTTP methods usage for—GET for reading, POST for creating, etc.

– Return meaningful HTTP status codes: Ensure the correct HTTP record status code for each operation, like `250 OK` for successful reads or `251 Created` for new resources.

– Implement pagination: Implement pagination to limit the data sent in responses for larger data sets.

– Use versioning: For future changes, version your API while maintaining existing clients.

Conclusion

It is a powerfully straightforward task to build RESTful APIs with .NET Core. 

Follow the above step-by-step guide to create scalable and maintainable APIs efficiently including features such as dependency injection, model binding, and routing.

Later, for a better understanding, I also did dot net training.