Step 1: Create entity

class Product
{
  public int ProductID {get;set;}
  public string ProductName {get;set;}
}

class Category
{
  public int CategoryID {get;set;}
  public string CategoryName {get;set;}
  public string Description {get;set;}
}

Step 2: create DBContext

class ProductContext : DbContext
{
  public ProductContext(DbContextOptions<ProductContext> options):base(options)
{
}

public DbSet<Product> Products {get;set;}

public DbSet<Category> Category {get;set;}

public override void OnModelCreating(ModelBuilder modelbuilder)
{
  modeulBuilder.Entity<Category>().HasData(
  new Category{
  CategoryID=1,
  Name = "Electronics",
  Description = "electronics items"
  },
  new Category{
  CategoryID=2,
  Name = "Clothes",
  Description = "dresses"
  })
}


}

Step 3: Create repository

interface IProductRepository
{
  IEnumerable<Product> getProducts();
  Product getProductById(int productid); 
  void InsertProduct(Product product);
  void UpdateProduct(Product product);
  void DeleteProduct(int productid);
  void Save();
}

class ProductRepository : IProductRepository
{
 ProductContext _productContext

 public ProductRepository (ProductContext productContext)
 { 
  _productContext = _productContext;
 }

 IEnumerable<Product> getProducts()
 {
   return _productContext.Products.ToList();
 }

 Product getProductById(int productid)
 {
  return _productContext.Products.Find(productid);
 }

 void InsertProduct(Product product);
 {
  _productContext.Add(product);
  Save();
 }

 void UpdateProduct(Product product)
 {
   _dbcontext.Entry(product).State = EntityState.Modified;
   Save();
 }

 void DeleteProduct(int productid)
 {
  var product = _dbContext.Products.Find(productID);
  _dbcontext.Products.Remove(product);
  Save();
 }

 void Save()
 {
  _dbContext.SaveChanges();
 }
}

Step 4: add connection string in appsettings.json

Step 5: register DB context & repository in startup.js

services.AddDbContext<ProductContext>(o => o.useSqlServer(Configurtion.GetConnectionString("ProductDB"));
services.AddTransient<IProductRepository,ProductRepository>();

6) create controller and inject repository in constructor

[Route("api\[controller]"]
[ApiController]
public class ProductController: ControllerBase
{ 
ProductRepository _productRepository;

public ProductController(IProductRepository productRepository)
{
_productRepository = productRepository;
}


[HttpGet]
public IActionResult GetProducts()
{
var product = _productRepository.getProducts();
return new OkObjectResult(product);
}

}

7) Extended the controller using http verb (get, post, put, delete)