允许员工每天标记一次考勤ASP.NET MVC

CREATE TABLE Employees (
    EmployeeId INT PRIMARY KEY IDENTITY(1,1),
    Name NVARCHAR(100) NOT NULL
);

CREATE TABLE Attendance (
    AttendanceId INT PRIMARY KEY IDENTITY(1,1),
    EmployeeId INT,
    Date DATE,
    Status NVARCHAR(50),
    FOREIGN KEY (EmployeeId) REFERENCES Employees(EmployeeId)
);

public class AttendanceController : Controller
{
    private readonly ApplicationDbContext _context;

    public AttendanceController(ApplicationDbContext context)
    {
        _context = context;
    }

    // GET: Attendance/MarkAttendance
    public IActionResult MarkAttendance(int employeeId)
    {
        var employee = _context.Employees.Find(employeeId);
        if (employee == null)
        {
            return NotFound();
        }

        var attendance = new Attendance
        {
            EmployeeId = employeeId,
            Date = DateTime.Today,
            Status = "Present"
        };

        _context.Attendance.Add(attendance);
        _context.SaveChanges();

        return RedirectToAction("Index", "Home");
    }
}

@model List<Attendance>

<table>
    <thead>
        <tr>
            <th>Employee Name</th>
            <th>Date</th>
            <th>Status</th>
        </tr>
    </thead>
    <tbody>
        @foreach (var attendance in Model)
        {
            <tr>
                <td>@attendance.Employee.Name</td>
                <td>@attendance.Date.ToString("yyyy-MM-dd")</td>
                <td>@attendance.Status</td>
            </tr>
        }
    </tbody>
</table>

public IActionResult MarkAttendance(int employeeId)
{
    var today = DateTime.Today;
    var existingAttendance = _context.Attendance.FirstOrDefault(a => a.EmployeeId == employeeId && a.Date == today);

    if (existingAttendance != null)
    {
        TempData["ErrorMessage"] = "You have already marked your attendance for today.";
        return RedirectToAction("Index", "Home");
    }

    // 继续保存考勤记录的逻辑
}