Asp.Net Web Api Get Post Put Delete Methods Explained Complete Guide

Step 1: Create a New ASP.NET Web API Project

1. Open Visual Studio.
2. Go to File > New > Project.
3. Select ASP.NET Core Web Application (or ASP.NET Web Application, depending on your .NET version preference) and click Next.
4. Give your project a name (e.g., WebApiTutorial) and choose the location to save it.
5. Click Create.
6. In the next dialog, choose the API template and click Create.

Step 2: Define a Model

Let's define a simple model Product:

using System.ComponentModel.DataAnnotations;

namespace WebApiTutorial.Models
{
    public class Product
    {
        [Key]
        public int Id { get; set; }

        [Required]
        public string Name { get; set; }

        [Range(1, 999999)]
        public decimal Price { get; set; }
    }
}

Step 3: Set Up an In-Memory Data Store

For simplicity, we'll use an in-memory list to store our Product data instead of a database:

using System.Collections.Generic;
using System.Linq;
using Microsoft.AspNetCore.Mvc;
using WebApiTutorial.Models;

namespace WebApiTutorial.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class ProductsController : ControllerBase
    {
        private static readonly List<Product> _products = new List<Product>
        {
            new Product { Id = 1, Name = "Laptop", Price = 999.99m },
            new Product { Id = 2, Name = "Smartphone", Price = 699.99m }
        };

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

        // GET: api/Products/5
        [HttpGet("{id}")]
        public ActionResult<Product> GetProduct(int id)
        {
            var product = _products.FirstOrDefault(p => p.Id == id);

            if (product == null)
            {
                return NotFound();
            }

            return product;
        }
        #endregion

        #region POST
        // POST: api/Products
        [HttpPost]
        public ActionResult<Product> PostProduct(Product product)
        {
            _products.Add(product);
            product.Id = _products.Count + 1; // Simple ID assignment
            return CreatedAtAction(nameof(GetProduct), new { id = product.Id }, product);
        }
        #endregion

        #region PUT
        // PUT: api/Products/5
        [HttpPut("{id}")]
        public IActionResult PutProduct(int id, Product product)
        {
            var existingProduct = _products.FirstOrDefault(p => p.Id == id);

            if (existingProduct == null)
            {
                return NotFound();
            }

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

            return NoContent(); // Return 204 No Content
        }
        #endregion

        #region DELETE
        // DELETE: api/Products/5
        [HttpDelete("{id}")]
        public IActionResult DeleteProduct(int id)
        {
            var product = _products.FirstOrDefault(p => p.Id == id);

            if (product == null)
            {
                return NotFound();
            }

            _products.Remove(product);

            return NoContent(); // Return 204 No Content
        }
        #endregion
    }
}

Step 4: Test the Endpoints

Now that we have our CRUD methods implemented, we can test them using tools like Postman or directly from a browser (for GET methods).

Testing with Postman

Download and install Postman if you haven't already.

GET All Products

• Method: GET
• URL: https://localhost:<port>/api/products

GET Product by ID

• Method: GET
• URL: https://localhost:<port>/api/products/1

POST New Product

• Method: POST
• URL: https://localhost:<port>/api/products
• Body:

  {
      "Name": "Headphones",
      "Price": 149.99
  }
  

PUT Update Product

• Method: PUT
• URL: https://localhost:<port>/api/products/3
• Body:

  {
      "Id": 3,
      "Name": "Updated Headphones",
      "Price": 139.99
  }
  

DELETE Product

• Method: DELETE
• URL: https://localhost:<port>/api/products/3

Explanation of the Code

GET Method