Restful API In .NET Core Using EF Core And Postgres

Create EF_DataContext inherited from DbContext class

using Microsoft.EntityFrameworkCore;
public class EF_DataContext: DbContext {
    public EF_DataContext(DbContextOptions < EF_DataContext > options): base(options) {}
    protected override void OnModelCreating(ModelBuilder modelBuilder) {
        modelBuilder.UseSerialColumns();
    }
    public DbSet <Product> Products {
        get;
        set;
    }
    public DbSet <Order> Orders {
        get;
        set;
    }
}

Step 5

Open appsetting.json

"ConnectionStrings": {
    "Ef_Postgres_Db": "Server=localhost;Database=shopingpostgres;Port=5432;User Id=postgres;Password=qwerty1234;"
}

Step 6

Open Program.cs

builder.Services.AddDbContext < EF_DataContext > (o => o.UseNpgsql(builder.Configuration.GetConnectionString("Ef_Postgres_Db")));

Step 7

Run the 2 commands

Add-Migration InitialDatabase
Update-Database

Step 8

Create the API Product and Order Models that will be used for API communication

public class Product {
    public int id {
        get;
        set;
    }
    public string ? name {
        get;
        set;
    }
    public string ? brand {
        get;
        set;
    }
    public string ? size {
        get;
        set;
    }
    public decimal price {
        get;
        set;
    }
}

public class Order {
    public int id {
        get;
        set;
    }
    public int product_id {
        get;
        set;
    }
    public string ? name {
        get;
        set;
    }
    public string ? address {
        get;
        set;
    }
    public string ? phone {
        get;
        set;
    }
    public DateTime createdon {
        get;
        set;
    }
    public virtual Product product {
        get;
        set;
    }
}

Step 9

Add the DBhelper class that will talk to your database

using ShoppingWebApi.EfCore;
namespace ShoppingWebApi.Model {
    public class DbHelper {
        private EF_DataContext _context;
        public DbHelper(EF_DataContext context) {
            _context = context;
        }
        /// <summary>
        /// GET
        /// </summary>
        /// <returns></returns>
        public List < ProductModel > GetProducts() {
            List < ProductModel > response = new List < ProductModel > ();
            var dataList = _context.Products.ToList();
            dataList.ForEach(row => response.Add(new ProductModel() {
                brand = row.brand,
                    id = row.id,
                    name = row.name,
                    price = row.price,
                    size = row.size
            }));
            return response;
        }
        public ProductModel GetProductById(int id) {
            ProductModel response = new ProductModel();
            var row = _context.Products.Where(d => d.id.Equals(id)).FirstOrDefault();
            return new ProductModel() {
                brand = row.brand,
                    id = row.id,
                    name = row.name,
                    price = row.price,
                    size = row.size
            };
        }
        /// <summary>
        /// It serves the POST/PUT/PATCH
        /// </summary>
        public void SaveOrder(OrderModel orderModel) {
            Order dbTable = new Order();
            if (orderModel.id > 0) {
                //PUT
                dbTable = _context.Orders.Where(d => d.id.Equals(orderModel.id)).FirstOrDefault();
                if (dbTable != null) {
                    dbTable.phone = orderModel.phone;
                    dbTable.address = orderModel.address;
                }
            } else {
                //POST
                dbTable.phone = orderModel.phone;
                dbTable.address = orderModel.address;
                dbTable.name = orderModel.name;
                dbTable.Product = _context.Products.Where(f => f.id.Equals(orderModel.product_id)).FirstOrDefault();
                _context.Orders.Add(dbTable);
            }
            _context.SaveChanges();
        }
        /// <summary>
        /// DELETE
        /// </summary>
        /// <param name="id"></param>
        public void DeleteOrder(int id) {
            var order = _context.Orders.Where(d => d.id.Equals(id)).FirstOrDefault();
            if (order != null) {
                _context.Orders.Remove(order);
                _context.SaveChanges();
            }
        }
    }
}

Step 10

Create your Api Controller name it as ShoppingRestApi

using Microsoft.AspNetCore.Mvc;
using ShoppingWebApi.EfCore;
using ShoppingWebApi.Model;
// For more information on enabling Web API for empty projects, visit https://go.microsoft.com/fwlink/?LinkID=397860
namespace ShoppingWebApi.Controllers {
    [ApiController]
    public class ShoppingApiController: ControllerBase {
        private readonly DbHelper _db;
        public ShoppingApiController(EF_DataContext eF_DataContext) {
            _db = new DbHelper(eF_DataContext);
        }
        // GET: api/<ShoppingApiController>
        [HttpGet]
        [Route("api/[controller]/GetProducts")]
        public IActionResult Get() {
            ResponseType type = ResponseType.Success;
            try {
                IEnumerable < ProductModel > data = _db.GetProducts();
                if (!data.Any()) {
                    type = ResponseType.NotFound;
                }
                return Ok(ResponseHandler.GetAppResponse(type, data));
            } catch (Exception ex) {
                return BadRequest(ResponseHandler.GetExceptionResponse(ex));
            }
        }
        // GET api/<ShoppingApiController>/5
        [HttpGet]
        [Route("api/[controller]/GetProductById/{id}")]
        public IActionResult Get(int id) {
            ResponseType type = ResponseType.Success;
            try {
                ProductModel data = _db.GetProductById(id);
                if (data == null) {
                    type = ResponseType.NotFound;
                }
                return Ok(ResponseHandler.GetAppResponse(type, data));
            } catch (Exception ex) {
                return BadRequest(ResponseHandler.GetExceptionResponse(ex));
            }
        }
        // POST api/<ShoppingApiController>
        [HttpPost]
        [Route("api/[controller]/SaveOrder")]
        public IActionResult Post([FromBody] OrderModel model) {
            try {
                ResponseType type = ResponseType.Success;
                _db.SaveOrder(model);
                return Ok(ResponseHandler.GetAppResponse(type, model));
            } catch (Exception ex) {
                return BadRequest(ResponseHandler.GetExceptionResponse(ex));
            }
        }
        // PUT api/<ShoppingApiController>/5
        [HttpPut]
        [Route("api/[controller]/UpdateOrder")]
        public IActionResult Put([FromBody] OrderModel model) {
            try {
                ResponseType type = ResponseType.Success;
                _db.SaveOrder(model);
                return Ok(ResponseHandler.GetAppResponse(type, model));
            } catch (Exception ex) {
                return BadRequest(ResponseHandler.GetExceptionResponse(ex));
            }
        }
        // DELETE api/<ShoppingApiController>/5
        [HttpDelete]
        [Route("api/[controller]/DeleteOrder/{id}")]
        public IActionResult Delete(int id) {
            try {
                ResponseType type = ResponseType.Success;
                _db.DeleteOrder(id);
                return Ok(ResponseHandler.GetAppResponse(type, "Delete Successfully"));
            } catch (Exception ex) {
                return BadRequest(ResponseHandler.GetExceptionResponse(ex));
            }
        }
    }
}

Step 11

Add the response model and response handler that will handle your API responses

namespace ShoppingWebApi.Model {
    public class ApiResponse {
        public string Code {
            get;
            set;
        }
        public string Message {
            get;
            set;
        }
        public object ? ResponseData {
            get;
            set;
        }
    }
    public enum ResponseType {
        Success,
        NotFound,
        Failure
    }
}

Now test the API's using POSTMAN as shown is video.

• SOURCE CODE GITHUB LINK