EF Core 写一个员工获取或者使用积分的功能

假设你已经建立了以下模型：

public class Employee
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int Points { get; set; }
}

public class Transaction
{
    public int Id { get; set; }
    public int EmployeeId { get; set; }
    public int Points { get; set; }
    public DateTime TransactionDate { get; set; }
    public bool IsRedeemed { get; set; }
}

你可以使用以下代码来扣除员工积分：

public async Task DeductPoints(int employeeId, int points)
{
    var employee = await _context.Employees.FindAsync(employeeId);
    if (employee == null) throw new ArgumentException("Invalid employee id");

    if (employee.Points < points) throw new ArgumentException("Insufficient points");

    employee.Points -= points;

    var transaction = new Transaction
    {
        EmployeeId = employeeId,
        Points = -points,
        TransactionDate = DateTime.UtcNow,
        IsRedeemed = false
    };

    _context.Transactions.Add(transaction);
    await _context.SaveChangesAsync();
}

你可以使用以下代码来为员工增加积分：

public async Task AddPoints(int employeeId, int points)
{
    var employee = await _context.Employees.FindAsync(employeeId);
    if (employee == null) throw new ArgumentException("Invalid employee id");

    employee.Points += points;

    var transaction = new Transaction
    {
        EmployeeId = employeeId,
        Points = points,
        TransactionDate = DateTime.UtcNow,
        IsRedeemed = false
    };

    _context.Transactions.Add(transaction);
    await _context.SaveChangesAsync();
}

你可以使用以下代码来获取员工的所有交易历史记录（包括增加和扣除积分的记录）：

public async Task<IEnumerable<Transaction>> GetTransactionHistory(int employeeId)
{
    return await _context.Transactions.Where(t => t.EmployeeId == employeeId).ToListAsync();
}