【ASP.NET Core MVC】Microsoft.Data.SqlClientを使ってCRUD機能を持つアプリを作成する

CREATE TABLE [dbo].[TodoItems] (
  [Id] INT IDENTITY NOT NULL PRIMARY KEY,
  [Name] NVARCHAR(50) NOT NULL,
  [IsComplete] BIT NOT NULL
);

INSERT INTO TodoItems VALUES(N'部屋の掃除', 'false')
INSERT INTO TodoItems VALUES(N'買い物', 'false')
INSERT INTO TodoItems VALUES(N'プログラミング学習', 'false')

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*",
  "ConnectionStrings": {
    "TodoConnection": "Server=(localdb)\\mssqllocaldb;Database=Todo;Trusted_Connection=True;MultipleActiveResultSets=true"
  }
}

using Microsoft.AspNetCore.Mvc;
using Microsoft.Data.SqlClient;
using MvcSqlCrudSample.Models;
using System.Data;

namespace MvcSqlCrudSample.Controllers
{
    public class HomeController : Controller
    {
        private readonly string _connectionString;

        public HomeController(IConfiguration configuration)
        {
            // appsettings.jsonファイルから接続文字列を取得
            _connectionString = configuration.GetConnectionString("TodoConnection") 
                ?? throw new ArgumentException("接続文字列が取得できませんでした");
        }

        /// <summary>
        /// ToDoアイテムを全件検索する
        /// </summary>
        public async Task<IActionResult> Index()
        {
            using var connection = new SqlConnection(_connectionString);
            using var command = connection.CreateCommand();

            await connection.OpenAsync();
            command.CommandText = "SELECT * FROM TodoItems";

            // テーブルのデータを全て読み取ってモデルのリストに格納
            var models = new List<TodoItemViewModel>();
            using var reader = command.ExecuteReader();
            while (await reader.ReadAsync())
            {
                models.Add(new TodoItemViewModel
                {
                    Id = (int)reader[nameof(TodoItemViewModel.Id)],
                    Name = reader[nameof(TodoItemViewModel.Name)].ToString(),
                    IsComplete = (bool)reader[nameof(TodoItemViewModel.IsComplete)],
                });
            }
            return View(new TodoItemViewModel { Items = models });
        }

        /// <summary>
        /// ToDoアイテムを登録してIndexにリダイレクトする
        /// </summary>
        [HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> Create([Bind("Name")] TodoItemViewModel todoItem)
        {
            if (ModelState.IsValid)
            {
                using var connection = new SqlConnection(_connectionString);
                using var command = connection.CreateCommand();

                await connection.OpenAsync();
                command.CommandText = "INSERT INTO TodoItems Values(@Name, 'false');";

                // フォームに入力されたタスク名をパラメータに設定
                command.Parameters.Add("@Name", SqlDbType.NVarChar).Value = todoItem.Name;

                // INSERT文の実行
                await command.ExecuteNonQueryAsync();
            }
            return RedirectToAction(nameof(Index));
        }

        /// <summary>
        /// 「完了」がクリックされた場合にToDoアイテムを削除し、Indexにリダイレクトする
        /// </summary>
        [HttpPost]
        public async Task<IActionResult> Delete([Bind("Id")] TodoItemViewModel todoItem)
        {
            if (ModelState.IsValid)
            {
                using var connection = new SqlConnection(_connectionString);
                using var command = connection.CreateCommand();

                await connection.OpenAsync();
                command.CommandText = "DELETE FROM TodoItems WHERE Id = @Id";
                command.Parameters.Add("@Id", SqlDbType.Int).Value = todoItem.Id;

                // DELETE文の実行
                await command.ExecuteNonQueryAsync();
            }
            return RedirectToAction(nameof(Index));
        }
    }
}

using System.ComponentModel.DataAnnotations;

namespace MvcSqlCrudSample.Models
{
    public class TodoItemViewModel
    {
        public int Id { get; set; }

        [Display(Name = "タスク")]
        public string? Name { get; set; } = string.Empty;

        [Display(Name = "完了チェック")]
        public bool IsComplete { get; set; }

        public List<TodoItemViewModel>? Items { get; set; }
    }
}

@model MvcSqlCrudSample.Models.TodoItemViewModel;

@{
    ViewData["Title"] = "ToDoリスト";
}

<h1>ToDoリスト</h1>

<p>
    <form asp-action="Create" method="post">
        <div class="form-group">
            <input asp-for="Name" />
            <input type="submit" value="タスクを登録" class="btn btn-primary" />
        </div>
    </form>
</p>

<table class="table">
    <thead>
        <tr>
            <th>
                @Html.DisplayNameFor(model => model.Id)
            </th>
            <th>
                @Html.DisplayNameFor(model => model.Name)
            </th>
            <th>
                @Html.DisplayNameFor(model => model.IsComplete)
            </th>
        </tr>
    </thead>
    <tbody>
        @foreach (var item in Model.Items)
        {
            <tr>
                <td>
                    @Html.DisplayFor(modelItem => item.Id)
                </td>
                <td>
                    @Html.DisplayFor(modelItem => item.Name)
                </td>
                <td>
                    <form asp-action="Delete" asp-route-id="@item.Id">
                        <input type="hidden" asp-for="@item.Id" />
                        <input type="submit" value="完了" class="btn btn-warning" />
                    </form>
                </td>
            </tr>
        }
    </tbody>
</table>