Asp.Net Web Api What Is A Web Api Complete Guide

What is a Web API?

Web API is a subset of web services designed to work with client-server architectures. It uses standard protocols like HTTP and typically returns data in formats such as JSON or XML. ASP.NET Web API is a framework provided by Microsoft for building web APIs on top of the ASP.NET platform.

Why Use ASP.NET Web API?

1. RESTful Support: ASP.NET Web API supports building RESTful services which are stateless and use standard HTTP verbs.
2. Performance: ASP.NET Web API is lightweight and provides better performance compared to traditional ASP.NET services.
3. Flexibility: You can use various data formats like JSON, XML, etc., and it supports self-hosting.

Step-by-Step Guide to Create an ASP.NET Web API

Let’s create a simple ASP.NET Web API that manages a list of products. Each product will have an ID, Name, and Price.

Step 1: Install Visual Studio

First, ensure you have Visual Studio installed on your machine. Any version starting from Visual Studio 2019 should be fine. Make sure to install the ASP.NET and web development workload during the setup.

Step 2: Create a New Project

1. Open Visual Studio.
2. Click on Create a new project.
3. In the search bar, type ASP.NET Core Web Application.
4. Select the template and click Next.
5. Configure your project name and location, then click Next.
6. Choose .NET Core and ASP.NET Core 6.0 (Long Term Support) (or later versions).
7. Under Application Type, select API and click Create.

Step 3: Define a Product Model

In the Models folder, add a new class named Product.cs.

namespace WebApiExample.Models
{
    public class Product
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public decimal Price { get; set; }
    }
}

Step 4: Create a Products Controller

In the Controllers folder, right-click and create a new controller named ProductsController.cs.

using Microsoft.AspNetCore.Mvc;
using WebApiExample.Models;
using System.Collections.Generic;

namespace WebApiExample.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class ProductsController : ControllerBase
    {
        private static readonly List<Product> Products = new()
        {
            new Product { Id = 1, Name = "Laptop", Price = 1200.00m },
            new Product { Id = 2, Name = "Smartphone", Price = 800.00m },
            new Product { Id = 3, Name = "Tablet", Price = 400.00m }
        };

        // GET: api/products
        [HttpGet]
        public ActionResult<IEnumerable<Product>> GetProducts()
        {
            return Ok(Products);
        }

        // GET: api/products/5
        [HttpGet("{id}")]
        public ActionResult<Product> GetProduct(int id)
        {
            var product = Products.Find(p => p.Id == id);
            if (product == null)
            {
                return NotFound();
            }
            return Ok(product);
        }

        // POST: api/products
        [HttpPost]
        public ActionResult<Product> PostProduct(Product product)
        {
            Products.Add(product);
            return CreatedAtAction(nameof(GetProduct), new { id = product.Id }, product);
        }

        // PUT: api/products/5
        [HttpPut("{id}")]
        public IActionResult PutProduct(int id, Product product)
        {
            var existingProduct = Products.Find(p => p.Id == id);
            if (existingProduct == null)
            {
                return NotFound();
            }

            existingProduct.Name = product.Name;
            existingProduct.Price = product.Price;

            return NoContent();
        }

        // DELETE: api/products/5
        [HttpDelete("{id}")]
        public IActionResult DeleteProduct(int id)
        {
            var productToDelete = Products.Find(p => p.Id == id);
            if (productToDelete == null)
            {
                return NotFound();
            }

            Products.Remove(productToDelete);

            return NoContent();
        }
    }
}

Step 5: Run Your ASP.NET Web API Project

Press F5 or click on the IIS Express button in the toolbar to run your project. By default, it will start at https://localhost:5001/ or http://localhost:5000/.

After the application starts, open a browser or use Postman to test the API.

Testing the Web API Endpoints

1. Get All Products:

   • URL: https://localhost:5001/api/products
   • Method: GET
   • Response (in JSON):

     [
         {
             "Id": 1,
             "Name": "Laptop",
             "Price": 1200.00
         },
         {
             "Id": 2,
             "Name": "Smartphone",
             "Price": 800.00
         },
         {
             "Id": 3,
             "Name": "Tablet",
             "Price": 400.00
         }
     ]
     

2. Get Single Product by ID:

   • URL: https://localhost:5001/api/products/1
   • Method: GET
   • Response (JSON):

     {
         "Id": 1,
         "Name": "Laptop",
         "Price": 1200.00
     }
     

3. Add a New Product:

   • URL: https://localhost:5001/api/products
   • Method: POST
   • Body (JSON):

     {
         "Name": "Smartwatch",
         "Price": 300.00
     }
     

   • Response: 201 Created, including the newly created product.

4. Update Existing Product:

   • URL: https://localhost:5001/api/products/2
   • Method: PUT
   • Body (JSON):

     {
         "Name": "Gaming Smartphone",
         "Price": 1000.00
     }
     

   • Response: 204 No Content

5. Delete a Product:

   • URL: https://localhost:5001/api/products/3
   • Method: DELETE
   • Response: 204 No Content

Summary

• A Web API is a service exposing endpoints over HTTP.
• ASP.NET Web API is a framework for building such services in .NET.
• You can define resources (e.g., Products) and corresponding endpoints (GET, POST, PUT, DELETE) using controllers.
• Testing can be done via browsers or tools like Postman.