たとえば、下記の画面で一括処理(POST)をしたいとします。

画面側でname属性を付与してサーバ側のModelクラスのProperty属性と一致させることで一括データをPOST送信させることができます。

【イメージ】
(フロント側)
@Model[i].employeeId

(サーバ側)
public int employeeId { get; set; }

👆のように全ての input, select, radio, checkbox にname="Employees[i].プロパティ名"を付けてます。

フロント側の実装

View/AdminUser/AdminEmployeeMember.cshtml

@removeTagHelper Microsoft.AspNetCore.Mvc.TagHelpers.OptionTagHelper, Microsoft.AspNetCore.Mvc.TagHelpers

@model List<ASPNETSQLServer.Models.AdminEmployeeViewModel>
@{
    ViewData["Title"] = "従業員名簿";
}

<form asp-action="SubmitEmployeeList" method="post">
    <div class="text-center">
        <h2>従業員名簿</h2>
        <table class="table table-bordered">
            <thead>
                <tr>
                    <th>従業員ID</th>
                    <th>部署</th>
                    <th>課</th>
                    <th>役職</th>
                    <th>従業員名</th>
                    <th>性別</th>
                    <th>IPアドレス</th>
                    <th>割り当て</th>
                </tr>
            </thead>
            <tbody>
                @for (int i = 0; i < Model.Count; i++)
                {
                    <tr>
                        <!-- hidden ID -->
                        <td>
                            @Model[i].employeeId
                            <input type="hidden" name="Employees[@i].employeeId" value="@Model[i].employeeId" />
                        </td>

                        <td>
                            <select class="form-select" name="Employees[@i].Department">
                                <option value="人事部" selected="@(Model[i].Department == "人事部")">人事部</option>
                                <option value="経理部" selected="@(Model[i].Department == "経理部")">経理部</option>
                                <option value="総務部" selected="@(Model[i].Department == "総務部")">総務部</option>
                                <option value="営業部" selected="@(Model[i].Department == "営業部")">営業部</option>
                                <option value="技術部" selected="@(Model[i].Department == "技術部")">技術部</option>
                                <option value="法務部" selected="@(Model[i].Department == "法務部")">法務部</option>
                                <option value="情報システム部" selected="@(Model[i].Department == "情報システム部")">情報システム部</option>
                            </select>
                        </td>

                        <td>
                            <select class="form-select" name="Employees[@i].Section">
                                <option value="人事課" selected="@(Model[i].Section == "人事課")">人事課</option>
                                <option value="経理課" selected="@(Model[i].Section == "経理課")">経理課</option>
                                <option value="総務課" selected="@(Model[i].Section == "総務課")">総務課</option>
                                <option value="営業課" selected="@(Model[i].Section == "営業課")">営業課</option>
                                <option value="技術課" selected="@(Model[i].Section == "技術課")">技術課</option>
                                <option value="法務課" selected="@(Model[i].Section == "法務課")">法務課</option>
                                <option value="情報システム課" selected="@(Model[i].Section == "情報システム課")">情報システム課</option>
                            </select>
                        </td>

                        <td>
                            <select class="form-select" name="Employees[@i].JobClass">
                                <option value="執行役員" selected="@(Model[i].JobClass == "執行役員")">執行役員</option>
                                <option value="部長" selected="@(Model[i].JobClass == "部長")">部長</option>
                                <option value="課長" selected="@(Model[i].JobClass == "課長")">課長</option>
                                <option value="主任" selected="@(Model[i].JobClass == "主任")">主任</option>
                                <option value="一般社員" selected="@(Model[i].JobClass == "一般社員")">一般社員</option>
                                <option value="契約社員" selected="@(Model[i].JobClass == "契約社員")">契約社員</option>
                                <option value="パート・アルバイト" selected="@(Model[i].JobClass == "パート・アルバイト")">パート・アルバイト</option>
                            </select>
                        </td>

                        <td>
                            <input type="text" class="form-control" name="Employees[@i].EmployeeName" value="@Model[i].EmployeeName" />
                        </td>

                        <td>
                            <input type="radio" name="Employees[@i].Sex" value="男性" @(Model[i].Sex == "男性" ? "checked" : "") /> 男
                            <input type="radio" name="Employees[@i].Sex" value="女性" @(Model[i].Sex == "女性" ? "checked" : "") /> 女
                        </td>

                        <td>
                            <input type="text" class="form-control" name="Employees[@i].Ipadress" value="@Model[i].Ipadress" />
                        </td>

                        <td class="text-center">
                            <input type="checkbox" name="Employees[@i].IpaddressAlocation" value="true" @(Model[i].IpaddressAlocation ? "checked" : "") />
                            <input type="hidden" name="Employees[@i].IpaddressAlocation" value="false" />
                        </td>
                    </tr>
                }
            </tbody>
        </table>
        <button type="submit" class="btn btn-primary">一括送信</button>
    </div>
</form>

バックエンド側の実装

Modelクラスは下記です。

Models/AdminEmployeeViewModel.cs

namespace ASPNETSQLServer.Models;
using System.ComponentModel.DataAnnotations;
using Microsoft.Identity.Client;

public class AdminEmployeeViewModel
{
    [Required]
    public int employeeId { get; set; }
    [Required]
    public string Department { get; set; }
    [Required]
    public string Section { get; set; }
    [Required]
    public string JobClass { get; set; }
    [Required]
    public string EmployeeName { get; set; }
    [Required]
    public string Ipadress { get; set; } 
    [Required]
    public string Sex { get; set; }
    public bool IpaddressAlocation { get; set; }
}

つづいて、Controllerクラスです。

Controllers/AdminUserController.cs

using System.Diagnostics;
using Microsoft.AspNetCore.Mvc;
using ASPNETSQLServer.Models;
using Microsoft.Extensions.Configuration;//追加
using Microsoft.Data.SqlClient;
using System.Data.Common;//追加
using ASPNETSQLServer.Models;
using Microsoft.AspNetCore.Mvc.RazorPages;
using System.Data;
using ASPNETSQLServer.Service;//追加
using Microsoft.AspNetCore.Http;
using System.Security.Claims;
using Microsoft.AspNetCore.Authentication.Cookies;
using Microsoft.AspNetCore.Authentication; // 追加
using System.Security.Claims; // 追加
using Microsoft.AspNetCore.Authentication; // 追加
using Microsoft.AspNetCore.Authentication.Cookies; // 追加

namespace ASPNETSQLServer.Controllers;

public class AdminUsersController : Controller
{
    private readonly ILogger<AdminUsersController> _logger;
    private readonly string _connectString;
    private readonly PasswordHash passwordHash;
    public AdminUsersController(ILogger<AdminUsersController> logger, IConfiguration configuration, PasswordHash passwordHash)
    {
        _logger = logger;
        _connectString = configuration.GetConnectionString("SqlServerConnection");
        this.passwordHash = passwordHash;
    }
    [HttpGet]
    public IActionResult Index()
    {
        // 既にログインしている場合はDashboardにリダイレクト
        if (User.Identity.IsAuthenticated)
        {
            return RedirectToAction("Dashboard", "AdminUsers");
        }
        return View();
    }

    [HttpPost]
    public async Task<IActionResult> AdminUserLogin(AdminUserViewModel adminUserViewModel)
    {
        string selectQuery = "SELECT name,email,password FROM [test].[dbo].[adminusers] WHERE name = @name AND email = @email";
        string employeeSelectQuery = "SELECT * FROM [test].[dbo].[employee]";
        List<AdminEmployeeViewModel> adminEmployeeViewModelsList = new List<AdminEmployeeViewModel>();
        List<AdminUserViewModel> adminUserViewModelsList = new List<AdminUserViewModel>();
        using (SqlConnection connection = new SqlConnection(_connectString))
        {
            using (SqlCommand command = new SqlCommand(selectQuery, connection))
            {
                command.Parameters.AddWithValue("@name", adminUserViewModel.AdminUserName);
                command.Parameters.AddWithValue("@email", adminUserViewModel.AdminUserEmail);
                try
                {
                    await connection.OpenAsync();
                    using (SqlDataReader reader = await command.ExecuteReaderAsync())
                    {
                        if (!reader.HasRows)
                        {
                            Object notFoundUser = new { status = 200, message = "ユーザー情報はありませんでした。" };
                            return Json(notFoundUser);
                        }
                        while (await reader.ReadAsync())
                        {
                            AdminUserViewModel adminUser = new AdminUserViewModel
                            {
                                AdminUserName = reader["name"].ToString(),
                                AdminUserEmail = reader["email"].ToString(),
                                AdminUserPassword = reader["password"].ToString(),
                            };
                            adminUserViewModelsList.Add(adminUser);
                        }
                    }
                    /*
                    // employeeテーブルから情報を取得 2025.7.28 追加
                    using (SqlDataReader reader = await command.ExecuteReaderAsync())
                    {
                        if (!reader.HasRows)
                        {
                            Object notFoundUser = new { status = 200, message = "ユーザー情報はありませんでした。" };
                            return Json(notFoundUser);
                        }
                        while (await reader.ReadAsync())
                        {
                            AdminEmployeeViewModel adminEmployeeViewModel = new AdminEmployeeViewModel
                            {
                                employeeId = reader["employeeId"] != DBNull.Value ? Convert.ToInt32(reader["employeeId"]) : 0,
                                Department = reader["department"].ToString(),
                                Section = reader["section"].ToString(),
                                JobClass = reader["jobclass"].ToString(),
                                EmployeeName = reader["name"].ToString(),
                                Ipadress = reader["ipaddress"].ToString(),
                                Sex = reader["sex"].ToString(),
                                IpaddressAlocation = reader["ipaddressalocation"] != DBNull.Value ? reader.GetBoolean(reader.GetOrdinal("ipaddressalocation")) : false,
                            };
                            adminEmployeeViewModelsList.Add(adminEmployeeViewModel);
                        }
                    }
                    */
                }
                catch (DbException dbException)
                {
                    Console.WriteLine($"データベースエラーが発生しました。。エラーメッセージ：{dbException}");
                }
                // 取得したデータに基づいて処理を行う
                if (adminUserViewModelsList.Count == 0)
                {
                    return Unauthorized(new { Message = "ユーザー名またはメールアドレスが間違っています。" });
                }
                // パスワードチェック
                string inputHashedPassword = passwordHash.HashPassword(adminUserViewModel.AdminUserPassword);
                if (inputHashedPassword != adminUserViewModelsList[0].AdminUserPassword)
                {
                    return Unauthorized(new { Message = "パスワードが間違っています。" });
                }
                AdminUserViewModel foundUser = adminUserViewModelsList[0];

                // 認証チケットの作成
                var claims = new List<Claim>
                {
                    new Claim(ClaimTypes.Name,foundUser.AdminUserName),
                    new Claim(ClaimTypes.Email,foundUser.AdminUserEmail)
                };

                var claimsIdentity = new ClaimsIdentity(
                    claims, CookieAuthenticationDefaults.AuthenticationScheme
                );

                var authProperties = new AuthenticationProperties
                {
                    // AllowRefresh = <bool>,
                    // IsPersistent = true, // 永続的なCookie（ブラウザを閉じても有効）にする場合
                    // ExpiresUtc = DateTimeOffset.UtcNow.AddMinutes(30), // 明示的な有効期限を設定
                    RedirectUri = Url.Action("Dashboard", "AdminUsers")// 認証後のリダイレクト先
                };

                // 認証Cookieを発行
                await HttpContext.SignInAsync(
                    CookieAuthenticationDefaults.AuthenticationScheme,
                    new ClaimsPrincipal(claimsIdentity),
                    authProperties
                );
                // セッションにデータを保存（例: ユーザーIDなど）
                // ASP.NET Coreのセッションは、Session Cookieを通じてサーバー側の状態を管理します。
                // 認証に成功したユーザーの識別情報などをセッションに保存することで、
                // 後続のリクエストでそのユーザーの状態を追跡できます。
                HttpContext.Session.SetString("AdminUserName", foundUser.AdminUserName);
                HttpContext.Session.SetString("AdminUserEmail", foundUser.AdminUserEmail);
                _logger.LogInformation($"ユーザー {foundUser.AdminUserName} がログインしました。");
                // ログイン成功後、Dashboardにリダイレクト
                return RedirectToAction("Dashboard", "AdminUsers");
            }
        }

    }

    [HttpGet]
    public IActionResult Dashboard()
    {
        // 認証されているかどうかを確認
        if (!User.Identity.IsAuthenticated)
        {
            // 認証されていない場合はログインページへリダイレクト
            return RedirectToAction("Index", "AdminUsers");
        }
        // セッションからユーザー情報を取得して表示することも可能
        ViewBag.AdminUserName = HttpContext.Session.GetString("AdminUserName");
        ViewBag.AdminUserEmail = HttpContext.Session.GetString("AdminUserEmail");
        return View();
    }

    [HttpGet]
    public async Task<IActionResult> Logout()
    {
        // 認証Cookieを削除し、ログアウト
        await HttpContext.SignOutAsync(CookieAuthenticationDefaults.AuthenticationScheme);
        // セッションをクリア
        HttpContext.Session.Clear();
        _logger.LogInformation("ユーザーがログアウトしました。");
        // ログアウト後、ログインページにリダイレクト
        return RedirectToAction("Index", "AdminUsers");
    }

    [HttpGet]
    public IActionResult AccessDenied()
    {
        return View();
    }

    [ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
    public IActionResult Error()
    {
        return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
    }

    [HttpGet]
    public IActionResult ArmyMembersRegistration()
    {
        return View();
    }
    [HttpPost]
    public async Task<IActionResult> EmployeeRegister(AdminEmployeeViewModel adminEmployeeViewModel)
    {
        // クエリ文字列
        string insertQuery = @"INSERT INTO 
                                    [test].[dbo].[employee] 
                                    (employeeId,department,section,jobclass,name,ipaddress,sex,ipaddressalocation) 
                                VALUES 
                                    (@employeeId,@department,@section,@jobclass,@name,@ipaddress,@sex,@ipaddressalocation);";
        using (SqlConnection connection = new SqlConnection(_connectString))
        {
            connection.Open();
            SqlTransaction transaction = connection.BeginTransaction();
            SqlCommand command = connection.CreateCommand();
            command.Transaction = transaction;
            try
            {
                command.CommandText = insertQuery;
                command.Parameters.Clear();
                command.Parameters.Add("@employeeId", SqlDbType.Int).Value = adminEmployeeViewModel.employeeId;
                command.Parameters.Add("@department", SqlDbType.NVarChar).Value = adminEmployeeViewModel.Department;
                command.Parameters.Add("@section", SqlDbType.NVarChar).Value = adminEmployeeViewModel.Section;
                command.Parameters.Add("@jobclass", SqlDbType.NVarChar).Value = adminEmployeeViewModel.JobClass;
                command.Parameters.Add("@name", SqlDbType.NVarChar).Value = adminEmployeeViewModel.EmployeeName;
                command.Parameters.Add("@ipaddress", SqlDbType.NVarChar).Value = adminEmployeeViewModel.Ipadress;
                command.Parameters.Add("@sex", SqlDbType.NVarChar).Value = adminEmployeeViewModel.Sex;
                command.Parameters.Add("@ipaddressalocation", SqlDbType.Bit).Value = adminEmployeeViewModel.IpaddressAlocation;
                int executeRow = command.ExecuteNonQuery();
                transaction.Commit();
                Console.WriteLine($"登録完了しました。実行件数：{executeRow}件");
                Object successObj = new { status = 200, message = "登録しました。" };
            }
            catch (DbException dbexception)
            {
                Console.WriteLine($"{dbexception}");
                transaction.Rollback();
            }
            catch (Exception exception)
            {
                Console.WriteLine($"{exception}");
                transaction.Rollback();
            }
        }
        return Redirect("./Index");
    }

    [HttpGet]
    public async Task<IActionResult> AdminEmployeeMember()
    {
        string employeeSelectQuery = "SELECT * FROM [test].[dbo].[employee]";
        List<AdminEmployeeViewModel> adminEmployeeViewModelsList = new List<AdminEmployeeViewModel>();
        using (SqlConnection connection = new SqlConnection(_connectString))
        {
            using (SqlCommand command = new SqlCommand(employeeSelectQuery, connection))
            {
                try
                {
                    await connection.OpenAsync();
                    using (SqlDataReader reader = await command.ExecuteReaderAsync())
                    {
                        if (!reader.HasRows)
                        {
                            Object notFoundUser = new { status = 200, message = "ユーザー情報はありませんでした。" };
                            return Json(notFoundUser);
                        }
                        while (await reader.ReadAsync())
                        {
                            AdminEmployeeViewModel adminEmployeeViewModel = new AdminEmployeeViewModel
                            {
                                employeeId = reader["employeeId"] != DBNull.Value ? Convert.ToInt32(reader["employeeId"]) : 0,
                                Department = reader["department"].ToString(),
                                Section = reader["section"].ToString(),
                                JobClass = reader["jobclass"].ToString(),
                                EmployeeName = reader["name"].ToString(),
                                Ipadress = reader["ipaddress"].ToString(),
                                Sex = reader["sex"].ToString(),
                                IpaddressAlocation = reader["ipaddressalocation"] != DBNull.Value ? reader.GetBoolean(reader.GetOrdinal("ipaddressalocation")) : false,
                            };
                            adminEmployeeViewModelsList.Add(adminEmployeeViewModel);
                        }
                    }
                }
                catch (DbException dbException)
                {
                    Console.WriteLine($"データベースエラーが発生しました。。エラーメッセージ：{dbException}");
                }
            }
        }
        return View(adminEmployeeViewModelsList);
    }

    [HttpPost]
    public IActionResult SubmitEmployeeList(List<AdminEmployeeViewModel> Employees)
    {
        string updateQuery = @"UPDATE [test].[dbo].[employee] WITH (ROWLOCK)
                               SET
                                department = @department,
                                section = @section,
                                jobclass = @jobclass,
                                name = @name,
                                ipaddress = @ipaddress,
                                sex = @sex,
                                ipaddressalocation = @ipaddressalocation
                               WHERE
                                employeeId = @employeeId                               
        ";
        using (SqlConnection connection = new SqlConnection(_connectString))
        {
            connection.Open();
            SqlTransaction transaction = connection.BeginTransaction();
            SqlCommand command = connection.CreateCommand();
            command.Transaction = transaction;
            try
            {
                foreach (var emp in Employees)
                {
                    using (command = new SqlCommand(updateQuery, connection))
                    {
                        command.Parameters.Add("@department", SqlDbType.NVarChar).Value = emp.Department;
                        command.Parameters.Add("@section", SqlDbType.NVarChar).Value = emp.Section;
                        command.Parameters.Add("@jobclass", SqlDbType.NVarChar).Value = emp.JobClass;
                        command.Parameters.Add("@name", SqlDbType.NVarChar).Value = emp.EmployeeName;
                        command.Parameters.Add("@ipaddress", SqlDbType.NVarChar).Value = emp.Ipadress;
                        command.Parameters.Add("@sex", SqlDbType.NVarChar).Value = emp.Sex;
                        command.Parameters.Add("@ipaddressalocation", SqlDbType.Bit).Value = emp.IpaddressAlocation;
                        command.Parameters.Add("@employeeId", SqlDbType.Int).Value = emp.employeeId;

                        // 行ロックを実行
                        int rowsAffected = command.ExecuteNonQuery();
                        Console.WriteLine($"従業員ID: {emp.employeeId} の更新：{rowsAffected}件");
                    }
                }
                // トランザクション実行
                transaction.Commit();
                TempData["Message"] = "一括更新に成功しました。";
            }
            catch (DbException dbexception)
            {
                Console.WriteLine(dbexception);
                _logger.LogError($"データベース接続に失敗しました。エラーメッセージ：{dbexception.Message}");
                transaction.Rollback();
            }
            catch (Exception e)
            {
                Console.WriteLine(e);
                _logger.LogError($"予期せぬエラーが発生しました。エラーメッセージ：{e.Message}");
                transaction.Rollback();
            }
        }
        // 完了後リダイレクトまたは再表示
        return RedirectToAction("AdminEmployeeMember");
    }
}