1. สร้างโปรเจ็กส์ด้วย Visual Studio 2019
2. ไฟล์ต่างๆในโปรเจ็กส์
3. เพิ่มคลาส Movie
4. สร้างคอนโทรลเลอร์ MovieController
5. ติดตั้ง Pomelo.EntityFrameworkCore.MySql
6. สร้างตารางที่ MySQL
7. ทดสอบ API

1.สร้างโปรเจ็กส์ด้วย Visual Studio 2019

สร้างโปรเจ็กส์ใหม่ เลือก Create a new project

เลือกภาษา C#

เลือก ASP.NET Core Web Application

ตั้งชื่อโปรเจ็กส์ WebApiDemo เสร็จแล้วกด Create

เลือก template เป็น API และที่ด้านบนเลือกเป็น .NET Core และ ASP.NET Core 3.0

รันทดสอบ จะไปที่ http://localhost:52744/weatherforecast และได้ค่า

[
    {
        "date": "2019-11-09T15:36:53.0790529+07:00",
        "temperatureC": 29,
        "temperatureF": 84,
        "summary": "Cool"
    },
    {
        "date": "2019-11-10T15:36:53.0814444+07:00",
        "temperatureC": 23,
        "temperatureF": 73,
        "summary": "Chilly"
    },
    {
        "date": "2019-11-11T15:36:53.0814498+07:00",
        "temperatureC": 6,
        "temperatureF": 42,
        "summary": "Cool"
    },
    {
        "date": "2019-11-12T15:36:53.0814502+07:00",
        "temperatureC": 6,
        "temperatureF": 42,
        "summary": "Chilly"
    },
    {
        "date": "2019-11-13T15:36:53.0814502+07:00",
        "temperatureC": -11,
        "temperatureF": 13,
        "summary": "Balmy"
    }
]

2.ไฟล์ต่างๆในโปรเจ็กส์

ไฟล์ WeatherForecast.cs

คลาส WeatherForecast

using System;

namespace WebApiDemo
{
    public class WeatherForecast
    {
        public DateTime Date { get; set; }

        public int TemperatureC { get; set; }

        public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);

        public string Summary { get; set; }
    }
}

ไฟล์ Controllers/WeatherForecastController.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;

namespace WebApiDemo.Controllers
{
    [ApiController]
    [Route("[controller]")]
    public class WeatherForecastController : ControllerBase
    {
        private static readonly string[] Summaries = new[]
        {
            "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
        };

        private readonly ILogger<WeatherForecastController> _logger;

        public WeatherForecastController(ILogger<WeatherForecastController> logger)
        {
            _logger = logger;
        }

        [HttpGet]
        public IEnumerable<WeatherForecast> Get()
        {
            var rng = new Random();
            return Enumerable.Range(1, 5).Select(index => new WeatherForecast
            {
                Date = DateTime.Now.AddDays(index),
                TemperatureC = rng.Next(-20, 55),
                Summary = Summaries[rng.Next(Summaries.Length)]
            })
            .ToArray();
        }
    }
}

ไฟล์ Startup.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace WebApiDemo
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }
}

ไฟล์ Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace WebApiDemo
{
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateHostBuilder(args).Build().Run();
        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                });
    }
}

ไฟล์ appsettings.json

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*"
}

ไฟล์ Properties/launchSettings.json

{
  "$schema": "http://json.schemastore.org/launchsettings.json",
  "iisSettings": {
    "windowsAuthentication": false,
    "anonymousAuthentication": true,
    "iisExpress": {
      "applicationUrl": "http://localhost:52744",
      "sslPort": 0
    }
  },
  "profiles": {
    "IIS Express": {
      "commandName": "IISExpress",
      "launchBrowser": true,
      "launchUrl": "weatherforecast",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      }
    },
    "WebApiDemo": {
      "commandName": "Project",
      "launchBrowser": true,
      "launchUrl": "weatherforecast",
      "applicationUrl": "http://localhost:5000",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      }
    }
  }
}

3.เพิ่มคลาส Movie

สร้างโฟลเดอร์ Models

สร้างไฟล์ Models/Movie.cs

using System;
using System.ComponentModel.DataAnnotations;

namespace WebApiDemo.Models
{
    public class Movie
    {
        public int Id { get; set; }
        public string Title { get; set; }

        [DataType(DataType.Date)]
        public DateTime ReleaseDate { get; set; }
        public string Genre { get; set; }
        public decimal Price { get; set; }
    }
}

4.สร้างคอนโทรลเลอร์ MovieController

คลิกขวาที่โฟลเดอร์ Controllers เลือก Add | Controller…

เลือก API Controller with actions, using Entity Framework

Model class เลือก Movie
Data context class สร้างใหม่ชื่อ MovieContext

กด Add

เสร็จแล้วจะได้ไฟล์ Data/MovieContext.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;

namespace WebApiDemo.Models
{
    public class MovieContext : DbContext
    {
        public MovieContext (DbContextOptions<MovieContext> options)
            : base(options)
        {
        }

        public DbSet<WebApiDemo.Models.Movie> Movie { get; set; }
    }
}

และได้ไฟล์ Controllers/MoviesController.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using WebApiDemo.Models;

namespace WebApiDemo.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class MoviesController : ControllerBase
    {
        private readonly MovieContext _context;

        public MoviesController(MovieContext context)
        {
            _context = context;
        }

        // GET: api/Movies
        [HttpGet]
        public async Task<ActionResult<IEnumerable<Movie>>> GetMovie()
        {
            return await _context.Movie.ToListAsync();
        }

        // GET: api/Movies/5
        [HttpGet("{id}")]
        public async Task<ActionResult<Movie>> GetMovie(int id)
        {
            var movie = await _context.Movie.FindAsync(id);

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

            return movie;
        }

        // PUT: api/Movies/5
        // To protect from overposting attacks, please enable the specific properties you want to bind to, for
        // more details see https://aka.ms/RazorPagesCRUD.
        [HttpPut("{id}")]
        public async Task<IActionResult> PutMovie(int id, Movie movie)
        {
            if (id != movie.Id)
            {
                return BadRequest();
            }

            _context.Entry(movie).State = EntityState.Modified;

            try
            {
                await _context.SaveChangesAsync();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!MovieExists(id))
                {
                    return NotFound();
                }
                else
                {
                    throw;
                }
            }

            return NoContent();
        }

        // POST: api/Movies
        // To protect from overposting attacks, please enable the specific properties you want to bind to, for
        // more details see https://aka.ms/RazorPagesCRUD.
        [HttpPost]
        public async Task<ActionResult<Movie>> PostMovie(Movie movie)
        {
            _context.Movie.Add(movie);
            await _context.SaveChangesAsync();

            return CreatedAtAction("GetMovie", new { id = movie.Id }, movie);
        }

        // DELETE: api/Movies/5
        [HttpDelete("{id}")]
        public async Task<ActionResult<Movie>> DeleteMovie(int id)
        {
            var movie = await _context.Movie.FindAsync(id);
            if (movie == null)
            {
                return NotFound();
            }

            _context.Movie.Remove(movie);
            await _context.SaveChangesAsync();

            return movie;
        }

        private bool MovieExists(int id)
        {
            return _context.Movie.Any(e => e.Id == id);
        }
    }
}

และเมื่อกลับไปดูที่ไฟล์ appsettings.json จะเห็นว่ามีการเพิ่ม ConnectionStrings

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*",
  "ConnectionStrings": {
    "MovieContext": "Server=(localdb)\\mssqllocaldb;Database=MovieContext-325717dc-d87d-4e13-9f43-362cef94252e;Trusted_Connection=True;MultipleActiveResultSets=true"
  }
}

แก้ไขจาก MS SQL เป็น MySQL ดังนี้

  "ConnectionStrings": {
    "MovieContext": "server=localhost;port=3306;database=mydbname;uid=myusername;password=mypassword"
  }

และที่ไฟล์ Startup.cs มีโค๊ดเชื่อมต่อ MS SQL เข้ามา

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();

            services.AddDbContext<MovieContext>(options =>
                  options.UseSqlServer(Configuration.GetConnectionString("MovieContext")));
        }

5.ติดตั้ง Pomelo.EntityFrameworkCore.MySql

• nuget Pomelo.EntityFrameworkCore.MySql
• nuget MySql.Data.EntityFrameworkCore (This package has been deprecated.)
• nuget MySql.EntityFrameworkCore
• nuget MySql.Data (Oracle)

PM> Install-Package Pomelo.EntityFrameworkCore.MySql -Version 3.0.0-rc3.final

แก้ไขเป็นเชื่อมต่อไปที่ MySql แทน

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();

            services.AddDbContext<MovieContext>(options =>
                    options.UseMySql(Configuration.GetConnectionString("MovieContext")));
        }

6.สร้างตารางที่ MySQL

CREATE TABLE `movie` (
  `Id` int(11) NOT NULL,
  `Title` longtext DEFAULT NULL,
  `ReleaseDate` datetime(6) NOT NULL,
  `Genre` longtext DEFAULT NULL,
  `Price` decimal(65,30) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

ALTER TABLE `movie`
  ADD PRIMARY KEY (`Id`);
COMMIT;

เพิ่มข้อมูลตัวอย่าง

INSERT INTO `movie` (`Id`, `Title`, `ReleaseDate`, `Genre`, `Price`) VALUES
(0, 'X-Men', '2019-11-01 00:00:00.000000', 'Action', '1.000000000000000000000000000000');

7.ทดสอบ API

เรียกไปที่ http://localhost:52744/api/movies จะได้

[
    {
        "id": 0,
        "title": "X-Men",
        "releaseDate": "2019-11-01T00:00:00",
        "genre": "Action",
        "price": 1.0000000000000000000000000000
    }
]