本篇同步發文在個人Blog: 一袋.NET要扛幾樓？打造容器化的ASP.NET Core網站！系列文章 - (20) 建立購物車系統 - 3

1. 新增CartController

在CartApi專案的資料夾Controllers，新增CartController類別且繼承ControllerBase，此類別是購物車系統的Http Api，之後要讓WebMvc呼叫。Action包含對購物車的更新、取得與刪除，需依靠注入的CartRepository物件。

using CartApi.Models;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;
using System.Net;
using System.Threading.Tasks;

namespace CartApi.Controllers
{
    [ApiController]
    [Route("api/[controller]")]
    public class CartController : ControllerBase
    {
        private readonly ILogger<CartController> _logger;
        private readonly ICartRepository _repository;

        public CartController(ILogger<CartController> logger, ICartRepository repository)
        {
            _logger = logger;
            _repository = repository;
        }

        [HttpGet("{id}")]
        [ProducesResponseType(typeof(Cart), (int)HttpStatusCode.OK)]
        public async Task<IActionResult> Get(string id)
        {
            var basket = await _repository.GetCartAsync(id);
            return Ok(basket);
        }

        [HttpPost]
        [ProducesResponseType(typeof(Cart), (int)HttpStatusCode.OK)]
        public async Task<IActionResult> Post([FromBody] Cart value)
        {
            var basket = await _repository.UpdateCartAsync(value);
            return Ok(basket);
        }

        [HttpDelete("{id}")]
        public void Delete(string id)
        {
            _repository.DeleteCartAsync(id);
        }
    }
} 

2. 修改Startup.cs

在Startup.cs，註冊所需的Redis、Repository服務。在AddControllers需要在Filters增加之前寫的HttpGlobalExceptionFilter功能，並且要安裝Microsoft.AspNetCore.Mvc.NewtonsoftJson，才能用AddNewtonsoftJson的功能，使Json不檢查自我參考的迴圈問題。Redis ConnectionMultiplexer註冊的是單例模式，不用每次都新增連線物件。

public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers(options =>
            {
                options.Filters.Add(typeof(HttpGlobalExceptionFilter));
            }).AddNewtonsoftJson(options => {
                options.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore;
            });

            services.Configure<CartSettings>(Configuration);

            services.AddSingleton<ConnectionMultiplexer>(sp =>
            {
                var settings = sp.GetRequiredService<IOptions<CartSettings>>().Value;
                var configuration = ConfigurationOptions.Parse(settings.ConnectionString, true);

                configuration.ResolveDns = true;
                configuration.AbortOnConnectFail = false;

                return ConnectionMultiplexer.Connect(configuration);
            });

            services.AddTransient<ICartRepository, CartRepository>();
            services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
        }

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之後再來寫Docker啟用Redis和使用Swagger測試CartController